Friday, August 6, 2010

I'm certified - MCTS

keep smiling

Today is my lucky and happy day. I finally got certified with ASP.NET 3.5. I was preparing it for the past few months. Today I finally get an award of it.

My exam time was scheduled at 11:30AM today. I left and headed to the test center an hour ahead of my exam time. It was just about 10 minutes drive but I was almost late and missed the time because of the incorrect Google map. I kept calling the test center but I could not reach anyone. I was panic and even thought that I might be doomed today. The time was ticking and I had only 10 minutes left. Finally, my call got through and I arrived just right on time. Still, my feeling was not so good that I was afraid what happened before was to give me some sort of symbolic or indication that I could fail my exam. However, the result turns out fantastic (a perfect one) and it makes me keep smiling.

The actual exam time lasts 180 minutes (3 hours) for 45 questions. But my confirmation sheet (from Prometric registration) said 4 hours because the additional hour was used for reading instructions, answering questions for survey (compulsorily) and leaving comments to questions after test (voluntarily). When I started taking the exam, the time was set to 180 and then counted down. I spent about 2 hours and read twice. The full score is 1000 and the passing mark is 700.

Monday, June 21, 2010

Double-click and right-click are extremely slow

In the past few months, one of my laptops running with windows XP responded very slowly to both double-click and right-click. Double-click to open a photo less than 1 KB takes more than a minute while the right-click sometimes might freeze the Windows Explorer. Everything works fine if I use the program to open it. This problem is not specific to any type of files.

Unlike others, this laptop didn't install many applications. It doesn't even have Microsoft Office on it. But it carries adobe reader, Nero burning software, AVG anti-virus, Spybot Seach & Destroy, and the default graphic card software by Intel. That's. It was used to be super fast.

Using ShellExView for diagnostics and disabling every single Context Menu Handler, Icon Handler and Property Sheet don't help. Finally the System File Checker (sfc) command fixed the problem.

sfc /scannow

Be sure to have your Windows installation CD ready before you issue the above command.

Now I enabled all the extensions that were disabled via ShellExView. Everything is back to normal now.

In this article, it mentions Context Menu handler for Intel® Graphics could be the possible culprit. But it isn't in my case. The problem I had was not only right-click but also double-click. Thus, if you have the similar trouble, you may have to trial-and-error to rule out the issue. Using ShellExView to find the root cause is extremely time-consuming because every change you make require a reboot in order to see the actual effect. Luckily I finally have my problem solved.

Saturday, June 12, 2010

The LoadDataRow and Delete Methods of DataTable

Oftentimes we encounter problems when we perform update using LoadDataRow or rollback data using RejectChanges after the Delete method. Why do the methods sometimes not do what we want?

Googling a solution for LoadDataRow, we may find that most people resolve the update performed by LoadDataRow must call DataTable.AcceptChanges first. Does this solution work for you 100%? There are still some unresolved posts left unanswered. They follow the solution to call AcceptChanges but the problem still exists. Why?

Deleting a DataRow and then immediately performing RejectAccepts to rollback cause us to receive System.Data.RowNotInTableException. What is it going on? Is the DataRow marked as Deleted? Why can't I rollback?

The above problems are related to either the RowState of a DataRow or if we set up the constraints on DataTable correctly.

continue Assuming there is no constraint problem, the DataRow must be either Unchanged or Modified when we perform an update using the LoadDataRow method on an existing DataRow. The same principle applies to the RejectChanges after calling the Delete method. Apparently, the operations requires an Original version existed for the DataRow. When the RowState of DataRow is Unchanged or Modified, an Original version of the DataRow has been created/existed. Thus, any operations after it won't cause a problem.

continueIf you receive a System.Data.ConstraintException in regard to System.Data.UniqueConstraint.CheckConstraint, please ensure the primary key set up properly. Most likely, setting the Unique property of a DataColumn without primary key to true will cause this problem to occur.

continueIf you receive a System.Data.ConstraintException in regard to System.Data.DataTable.EnableConstraints, please ensure an Original version existed for the DataRow. It means the RowState of the DataRow is still in the state of Added and you need to commit changes first by calling the AcceptChanges method to update the state to Unchanged.

continueSimilarly, if you receive a System.Data.RowNotInTableException when you try to roll back the DataRow after having called the Delete method, a AcceptChanges call is required before the Delete method. After AcceptChanges, an Original version of the DataRow is created and the RowState of the DataRow is set to Unchanged. From this state onwards, any modification including the LoadDataRow method, or calling the Delete method and then the RejectChanges method can be performed.

To sum up what the RowState means is described in the following table.
DetachedThe DataRow is created but it hasn't been added to a DataTable yet. Since it does not exist in a DataTable, no operations can be performed at the DataTable level.
AddedThe DataRow is added to a DataTable but the DataTable has not accepted changes yet. At this stage, it requires AcceptChanges to create Original version for other update operations including rollback.
UnchangedThe DataRow has not changed since the last AcceptChanges call. At this stage, an Original version of the DataRow has already existed. Thus, any operations can be performed without a problem.
ModifiedThe DataRow has been modified since the last AcceptChanges call. Like Unchanged, an Original version of the DataRow has already existed in this stage. A DataRow with Modified row state can continously be modified but the RejectChanges will only roll the data back to the last AcceptChanges call. Any modification made in between is disgarded because the Original version of the DataRow is only pointing the copy when the last AcceptChanges is called.
DeletedThe DataRow was deleted by using the Delete method of the DataRow only when the RowState of the DataRow is Unchanged or Modified.

I also attach some test results I conducted for reference.

Friday, June 11, 2010

About DataRow.Delete, .AcceptChanges and .RejectChanges

See The LoadDataRow and Delete Methods of DataTable for intention.

Purpose

The following 3 tests [ Test 1 | Test 2 | Test 3 ] tell you about in which situation you can roll back your data and when you cannot.

This page is generated by the application developed in C# under Visual 2008 Profession SP + .NET 3.5 SP1 on Windows XP Professional SP3.

Test 1: No AcceptChanges before deletion
  • Set up a DataTable with 2 rows; so the initial RowState of all DataRows is Added.
  • Without AcceptChanges, immediately delete the 2nd DataRow using Delete method.
  • The RowState of the deleted row is not Deleted but Detached; The result is different from what it is said in the documentation [According to MSDN, it is currently supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0]. Please also see the test foot notes in blue.
  • Then RejectChanges after deletion; unfortunately, the System.Data.RowNotInTableException is received.

EmpIdFirstNameLastNameSalaryLastName and FirstNameRowState
A123456789BettyeWilliams11.00Williams, BettyeAdded
B223456789RexBloomer12.00Bloomer, RexAdded

Initial state: [B223456789, Rex] RowState: Added
Version: Original doesn't not exist.
Version: Current Value: Rex
Version: Proposed doesn't not exist.
Version: Default Value: Rex

Using Delete method to delete [B223456789, Rex] at RowState: Added...
EmpIdFirstNameLastNameSalaryLastName and FirstNameRowState
A123456789BettyeWilliams11.00Williams, BettyeAdded

The deleted row after deletion: RowState: Detached
Version: Original doesn't not exist.
Version: Current doesn't not exist.
Version: Proposed doesn't not exist.
Version: Default doesn't not exist.

This row has been removed from a table and does not have any data.  BeginEdit() will allow creation of new data in this row.
System.Data.RowNotInTableException
at System.Data.DataRow.GetDefaultRecord() at System.Data.DataColumn.CheckNullable(DataRow row) at System.Data.DataColumn.CheckColumnConstraint(DataRow row, DataRowAction action) at System.Data.DataTable.RaiseRowChanging(DataRowChangeEventArgs args, DataRow eRow, DataRowAction eAction, Boolean fireEvent) at System.Data.DataTable.SetNewRecordWorker(DataRow row, Int32 proposedRecord, DataRowAction action, Boolean isInMerge, Int32 position, Boolean fireEvent, Exception& deferredException) at System.Data.DataTable.SetNewRecord(DataRow row, Int32 proposedRecord, DataRowAction action, Boolean isInMerge, Boolean fireEvent) at System.Data.DataTable.RollbackRow(DataRow row) at System.Data.DataRow.RejectChanges() ...

After error: RowState: Detached
Version: Original doesn't not exist.
Version: Current doesn't not exist.
Version: Proposed doesn't not exist.
Version: Default doesn't not exist.

  • By definition of DataRow.Delete method, the row should have been marked as Deleted.
  • According to this, this bug should have been fixed in VS 2008. Apparently, it still exists. Or there may be a typo in the document. Originally it said, "If the RowState of the row is Added, the RowState becomes Detached and the row is removed from the table when you call AcceptChanges." Perhaps, it is meant to say, ""If the RowState of the row is Added, the RowState becomes Detached and the row is removed from the table when you call RejectChanges." Then everything will become and make more sense.
  • Because DataRow.RowState is set to Detached, we cannot roll it back by using RejectChanges.


Test 2: AcceptChanges before deletion
  • Set up a DataTable with 2 rows; so the initial RowState of all DataRows is Added.
  • Then AcceptChanges, which changes the RowState from Added to Unchanged.
  • Delete the 2nd DataRow using Delete method. The RowState of the 2nd DataRow is marked as Deleted now.
  • Immdiately RejectChanges after deletion, which changes the RowState from Deleted back to Unchanged

EmpIdFirstNameLastNameSalaryLastName and FirstNameRowState
A123456789BettyeWilliams11.00Williams, BettyeAdded
B223456789RexBloomer12.00Bloomer, RexAdded

Initial state: [B223456789, Rex] RowState: Added
Version: Original doesn't not exist.
Version: Current Value: Rex
Version: Proposed doesn't not exist.
Version: Default Value: Rex

AcceptChanges. [B223456789, Rex] RowState: Unchanged
Version: Original Value: Rex
Version: Current Value: Rex
Version: Proposed doesn't not exist.
Version: Default Value: Rex

Using Delete method to delete [B223456789, Rex] at RowState: Unchanged...
EmpIdFirstNameLastNameSalaryLastName and FirstNameRowState
A123456789BettyeWilliams11.00Williams, BettyeUnchanged
?????Deleted

The deleted row after deletion: RowState: Deleted
Version: Original Value: Rex
Version: Current doesn't not exist.
Version: Proposed doesn't not exist.
Version: Default doesn't not exist.

RejectChanges:
EmpIdFirstNameLastNameSalaryLastName and FirstNameRowState
A123456789BettyeWilliams11.00Williams, BettyeUnchanged
B223456789RexBloomer12.00Bloomer, RexUnchanged

[B223456789, Rex] RowState: Unchanged
Version: Original Value: Rex
Version: Current Value: Rex
Version: Proposed doesn't not exist.
Version: Default Value: Rex

  • After deletion using Delete method, the RowState is set to Deleted.
  • Thus, RejectChanges can be used to roll back the DataRow to the point where the AcceptChanges method is last called.
  • The RowState of the deleted row is also rolled back to Unchanged. Everything looks exactly like before deletion.

Test 3: AcceptChanges, modification and then deletion
  • Set up a DataTable with 2 rows; so the initial RowState of all DataRows is Added.
  • Then AcceptChanges, which changes the RowState from Added to Unchanged.
  • Start BeginEdit ... EndEdit block to modify the 2nd row. Change the FirstName from Rex to Susan.
  • The expression column LastName and FirstName remains unchanged until the EndEdit method is called while FirstName is modified before calling EndEdit.
  • Then delete the 2nd DataRow using Delete method. The RowState of the 2nd DataRow is marked as Deleted now.
  • Immdiately RejectChanges after deletion, which changes everything back to the state when the AcceptChanges is last called; thus the RowState is rolled back all the way from Deleted to Unchanged

EmpIdFirstNameLastNameSalaryLastName and FirstNameRowState
A123456789BettyeWilliams11.00Williams, BettyeAdded
B223456789RexBloomer12.00Bloomer, RexAdded

Initial state: [B223456789, Rex] RowState: Added
Version: Original doesn't not exist.
Version: Current Value: Rex
Version: Proposed doesn't not exist.
Version: Default Value: Rex

AcceptChanges. [B223456789, Rex] RowState: Unchanged
Version: Original Value: Rex
Version: Current Value: Rex
Version: Proposed doesn't not exist.
Version: Default Value: Rex

BeginEdit and modified the 2nd row:
 row.BeginEdit(); row["FirstName"] = "Susan";

EmpIdFirstNameLastNameSalaryLastName and FirstNameRowState
A123456789BettyeWilliams11.00Williams, BettyeUnchanged
B223456789SusanBloomer12.00Bloomer, RexUnchanged
[B223456789, Susan] RowState: Unchanged
Version: Original Value: Rex
Version: Current Value: Rex
Version: Proposed Value: Susan
Version: Default Value: Susan

After EndEdit:
  row.EndEdit();

EmpIdFirstNameLastNameSalaryLastName and FirstNameRowState
A123456789BettyeWilliams11.00Williams, BettyeUnchanged
B223456789SusanBloomer12.00Bloomer, SusanModified
[B223456789, Susan] RowState: Modified
Version: Original Value: Rex
Version: Current Value: Susan
Version: Proposed doesn't not exist.
Version: Default Value: Susan

Using Delete method to delete [B223456789, Susan] at RowState: Modified...
EmpIdFirstNameLastNameSalaryLastName and FirstNameRowState
A123456789BettyeWilliams11.00Williams, BettyeUnchanged
?????Deleted

The deleted row after deletion: RowState: Deleted
Version: Original Value: Rex
Version: Current doesn't not exist.
Version: Proposed doesn't not exist.
Version: Default doesn't not exist.

RejectChanges:
EmpIdFirstNameLastNameSalaryLastName and FirstNameRowState
A123456789BettyeWilliams11.00Williams, BettyeUnchanged
B223456789RexBloomer12.00Bloomer, RexUnchanged

[B223456789, Rex] RowState: Unchanged
Version: Original Value: Rex
Version: Current Value: Rex
Version: Proposed doesn't not exist.
Version: Default Value: Rex

Interesting of this test is that the "LastName and FirstName" column remains unchanged [Bloomer, Rex] after the FirstName has been modified to Susan. The "LastName and FirstName" column is an Expression column set up by expression that contains the values from both FirstName and LastName columns. Changing FirstName will not refect the change immediately in the "FirstName and LastName" column until EndEdit is called.

Wednesday, June 9, 2010

LoadDataRow(object[], bool) and ConstraintException

See The LoadDataRow and Delete Methods of DataTable for intention.


Introduction

In this test, I will use LoadDataRow to perform content update on a DataTable with or without primary key constraint. bool AcceptChanges will be passed as a parameter in LoadDataRow(object[], bool). For result using LoadDataRow(object[], LoadOption), please see this.

When the LoadDataRow method is call, the following statement is used:
   employee.LoadDataRow(
      new object[] { "B223456789", "Denise", "Miller", 13.00 },
      false);  // don't AcceptChanges
When primary key is applied, the following statement is used and it will be executed before the LoadDataRow method:
   employee.PrimaryKey = new DataColumn[] {eid}; // eid is the EmpId column   

The DataTable used for the test has the five (5) columns and initially is populated with 2 sample data rows.
ColumnNameEmpIdFirstNameLastNameSalaryLastName and FirstName **
DataTypestringstringstringdecimalstring
MaxLength1035-1-170
Uniquetruefalsefalsefalsefalse
AllowDBNullfalsefalsefalsetruetrue

** The column of LastName and FirstName is defined as an expression column containing the values from the column of LastName and the column of FirstName.

Every test is based on this table with the initial sample data. The 2nd row is the target to update by using the LoadDataRow method. A grid shown in each test is represented the final result of the DataTable even though the update performed by the LoadDataRow method may fail. Execution messages about the RowState of the 2nd row and its versions are shown afterwards. For clarity, the initial state of the 2nd row is also attached to each test for reference.

The rest of the page is generated by the application developed in C# under Visual 2008 Profession SP + .NET 3.5 SP1 on Windows XP Professional SP3.


Set up a DataTable with 2 rows
- EmpId is the unique key (eid.Unique = true).
- Primary key is not set up initially.

  • Initial Table:
  • EmpIdFirstNameLastNameSalaryLastName and FirstName
    A123456789BettyeWilliams11.00Williams, Bettye
    B223456789RexBloomer12.00Bloomer, Rex

  • Status duing execution:
  • Initial state: [B223456789, Rex] RowState: Added
    Version: Original doesn't not exist.
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex


No primary key applied
Expect errors [System.Data.UniqueConstraint.CheckConstraint]!
The last row remains unchanged.

  • Resulted DataTable:
  • EmpIdFirstNameLastNameSalaryLastName and FirstName
    A123456789BettyeWilliams11.00Williams, Bettye
    B223456789RexBloomer12.00Bloomer, Rex

  • Status duing execution:
  • Initial state: [B223456789, Rex] RowState: Added
    Version: Original doesn't not exist.
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex

    Executing LoadDataRow(...)
    Column 'EmpId' is constrained to be unique.  Value 'B223456789' is already present.
    System.Data.ConstraintException
    at System.Data.UniqueConstraint.CheckConstraint(DataRow row, DataRowAction action) at System.Data.DataTable.RaiseRowChanging(DataRowChangeEventArgs args, DataRow eRow, DataRowAction eAction, Boolean fireEvent) at System.Data.DataTable.SetNewRecordWorker(DataRow row, Int32 proposedRecord, DataRowAction action, Boolean isInMerge, Int32 position, Boolean fireEvent, Exception& deferredException) at System.Data.DataTable.InsertRow(DataRow row, Int32 proposedID, Int32 pos, Boolean fireEvent) at System.Data.DataRowCollection.Add(Object[] values) at System.Data.DataTable.UpdatingAdd(Object[] values) at System.Data.DataTable.LoadDataRow(Object[] values, Boolean fAcceptChanges) ...

    After error: [B223456789, Rex] RowState: Added
    Version: Original doesn't not exist.
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex


Primary key applied, no AcceptChanges before or after LoadDataRow
Expect errors [System.Data.UniqueConstraint.CheckConstraint]!
The last row remains unchanged.

  • Resulted DataTable:
  • EmpIdFirstNameLastNameSalaryLastName and FirstName
    A123456789BettyeWilliams11.00Williams, Bettye
    B223456789RexBloomer12.00Bloomer, Rex

  • Status duing execution:
  • Initial state: [B223456789, Rex] RowState: Added
    Version: Original doesn't not exist.
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex

    Executing LoadDataRow(...)
    Column 'EmpId' is constrained to be unique.  Value 'B223456789' is already present.
    System.Data.ConstraintException
    at System.Data.UniqueConstraint.CheckConstraint(DataRow row, DataRowAction action) at System.Data.DataTable.RaiseRowChanging(DataRowChangeEventArgs args, DataRow eRow, DataRowAction eAction, Boolean fireEvent) at System.Data.DataTable.SetNewRecordWorker(DataRow row, Int32 proposedRecord, DataRowAction action, Boolean isInMerge, Int32 position, Boolean fireEvent, Exception& deferredException) at System.Data.DataTable.InsertRow(DataRow row, Int32 proposedID, Int32 pos, Boolean fireEvent) at System.Data.DataTable.UpdatingAdd(Object[] values) at System.Data.DataTable.LoadDataRow(Object[] values, Boolean fAcceptChanges) ...

    After error: [B223456789, Rex] RowState: Added
    Version: Original doesn't not exist.
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex


No primary key, AcceptChanges before LoadDataRow
Expect errors [System.Data.UniqueConstraint.CheckConstraint]!
The last row remains unchanged.

  • Resulted DataTable:
  • EmpIdFirstNameLastNameSalaryLastName and FirstName
    A123456789BettyeWilliams11.00Williams, Bettye
    B223456789RexBloomer12.00Bloomer, Rex

  • Status duing execution:
  • Initial state: [B223456789, Rex] RowState: Added
    Version: Original doesn't not exist.
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex

    Apply AcceptChanges(): [B223456789, Rex] RowState: Unchanged
    Version: Original Value: Rex
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex

    Executing LoadDataRow(...)
    Column 'EmpId' is constrained to be unique.  Value 'B223456789' is already present.
    System.Data.ConstraintException
    at System.Data.UniqueConstraint.CheckConstraint(DataRow row, DataRowAction action) at System.Data.DataTable.RaiseRowChanging(DataRowChangeEventArgs args, DataRow eRow, DataRowAction eAction, Boolean fireEvent) at System.Data.DataTable.SetNewRecordWorker(DataRow row, Int32 proposedRecord, DataRowAction action, Boolean isInMerge, Int32 position, Boolean fireEvent, Exception& deferredException) at System.Data.DataTable.InsertRow(DataRow row, Int32 proposedID, Int32 pos, Boolean fireEvent) at System.Data.DataRowCollection.Add(Object[] values) at System.Data.DataTable.UpdatingAdd(Object[] values) at System.Data.DataTable.LoadDataRow(Object[] values, Boolean fAcceptChanges) ...

    After error: [B223456789, Rex] RowState: Unchanged
    Version: Original Value: Rex
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex


Primary key applied, AcceptChanges before LoadDataRow
No error! The last row is updated.

  • Resulted DataTable:
  • EmpIdFirstNameLastNameSalaryLastName and FirstName
    A123456789BettyeWilliams11.00Williams, Bettye
    B223456789DeniseMiller13.00Miller, Denise

  • Status duing execution:
  • Initial state: [B223456789, Rex] RowState: Added
    Version: Original doesn't not exist.
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex

    Apply AcceptChanges(): [B223456789, Rex] RowState: Unchanged
    Version: Original Value: Rex
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex

    Executing LoadDataRow(...)
    After LoadDataRow: [B223456789, Denise] RowState: Modified
    Version: Original Value: Rex
    Version: Current Value: Denise
    Version: Proposed doesn't not exist.
    Version: Default Value: Denise


No primary key, LoadDataRow in conjunction with Begin/EndLoadData
Expect errors [System.Data.DataTable.EnableConstraints()]!
Duplicate rows are found.

  • Resulted DataTable:
  • EmpIdFirstNameLastNameSalaryLastName and FirstName
    A123456789BettyeWilliams11.00Williams, Bettye
    B223456789RexBloomer12.00Bloomer, Rex
    B223456789DeniseMiller13.00Miller, Denise

  • Status duing execution:
  • Initial state: [B223456789, Rex] RowState: Added
    Version: Original doesn't not exist.
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex

    BeginLoadData(): turn off notification/constraints/indexing.

    Executing LoadDataRow(...)
    After LoadDataRow: [B223456789, Denise] RowState: Added
    Version: Original doesn't not exist.
    Version: Current Value: Denise
    Version: Proposed doesn't not exist.
    Version: Default Value: Denise

    EndLoadData(): turn on validation, constraints, etc.

    Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints.
    System.Data.ConstraintException
    at System.Data.DataTable.EnableConstraints() at System.Data.DataTable.set_EnforceConstraints(Boolean value) at System.Data.DataTable.EndLoadData() ...

    After error: [B223456789, Rex] RowState: Added
    Version: Original doesn't not exist.
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex


Primary key applied, LoadDataRow in conjunction with Begin/EndLoadData
Expect errors [System.Data.DataTable.EnableConstraints()]!
Duplicate rows are found.

  • Resulted DataTable:
  • EmpIdFirstNameLastNameSalaryLastName and FirstName
    A123456789BettyeWilliams11.00Williams, Bettye
    B223456789RexBloomer12.00Bloomer, Rex
    B223456789DeniseMiller13.00Miller, Denise

  • Status duing execution:
  • Initial state: [B223456789, Rex] RowState: Added
    Version: Original doesn't not exist.
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex

    BeginLoadData(): turn off notification/constraints/indexing.

    Executing LoadDataRow(...)
    After LoadDataRow: [B223456789, Denise] RowState: Added
    Version: Original doesn't not exist.
    Version: Current Value: Denise
    Version: Proposed doesn't not exist.
    Version: Default Value: Denise

    EndLoadData(): turn on validation, constraints, etc.

    Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints.
    System.Data.ConstraintException
    at System.Data.DataTable.EnableConstraints() at System.Data.DataTable.set_EnforceConstraints(Boolean value) at System.Data.DataTable.EndLoadData() ...

    After error: [B223456789, Rex] RowState: Added
    Version: Original doesn't not exist.
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex


Primary key applied, LoadDataRow in conjunction with Begin/EndLoadData, ApplyChanges before BeginLoadData
No error! The last row is updated.

  • Resulted DataTable:
  • EmpIdFirstNameLastNameSalaryLastName and FirstName
    A123456789BettyeWilliams11.00Williams, Bettye
    B223456789DeniseMiller13.00Miller, Denise

  • Status duing execution:
  • Initial state: [B223456789, Rex] RowState: Added
    Version: Original doesn't not exist.
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex

    Apply AcceptChanges(): [B223456789, Rex] RowState: Unchanged
    Version: Original Value: Rex
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex

    BeginLoadData(): turn off notification/constraints/indexing.

    Executing LoadDataRow(...)
    After LoadDataRow: [B223456789, Denise] RowState: Modified
    Version: Original Value: Rex
    Version: Current Value: Denise
    Version: Proposed doesn't not exist.
    Version: Default Value: Denise

    EndLoadData(): turn on validation, constraints, etc.

    [B223456789, Denise] RowState: Modified
    Version: Original Value: Rex
    Version: Current Value: Denise
    Version: Proposed doesn't not exist.
    Version: Default Value: Denise

LoadDataRow(object[], LoadOption) and ConstraintException

See The LoadDataRow and Delete Methods of DataTable for intention.


Introduction

In this test, I will use LoadDataRow to perform content update on a DataTable with or without primary key constraint. LoadOption is passed in a parameter with this call LoadDataRow(object[], LoadOption). For result using LoadDataRow(object[], bool), please see this.

When the LoadDataRow method is call, the following statement is used:
   employee.LoadDataRow(
      new object[] { "B223456789", "Denise", "Miller", 13.00 },
      LoadOption.OverwriteChanges);
When primary key is applied, the following statement is used and it will be executed before the LoadDataRow method:
   employee.PrimaryKey = new DataColumn[] {eid}; // eid is the EmpId column  

Before presenting the test results, we will first set up a DataTable with 2 rows without primary key constraint. Our DataTable will have the following columns:
ColumnNameEmpIdFirstNameLastNameSalaryLastName and FirstName **
DataTypestringstringstringdecimalstring
MaxLength1035-1-170
Uniquetruefalsefalsefalsefalse
AllowDBNullfalsefalsefalsetruetrue

** The column of LastName and FirstName is defined as an expression column containing the values from the column of LastName and the column of FirstName.

Every test is based on this table with the initial sample data. The 2nd row is the target to update by using the LoadDataRow method. A grid shown in each test is represented the final result of the DataTable even though the update performed by the LoadDataRow method may fail. Execution messages about the RowState of the 2nd row and its versions are shown afterwards. For clarity, the initial state of the 2nd row is also attached to each test for reference.

The rest of the page is generated by the application developed in C# under Visual 2008 Profession SP + .NET 3.5 SP1 on Windows XP Professional SP3.


Set up a DataTable with 2 rows
- EmpId is the unique key (eid.Unique = true).
- Primary key is not set up initially.

  • Initial Table:
  • EmpIdFirstNameLastNameSalaryLastName and FirstName
    A123456789BettyeWilliams11.00Williams, Bettye
    B223456789RexBloomer12.00Bloomer, Rex

  • Status duing execution:
  • Initial state: [B223456789, Rex] RowState: Added
    Version: Original doesn't not exist.
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex


No primary key applied
Expect errors [System.Data.UniqueConstraint.CheckConstraint]!
The last row remains unchanged.

  • Resulted DataTable:
  • EmpIdFirstNameLastNameSalaryLastName and FirstName
    A123456789BettyeWilliams11.00Williams, Bettye
    B223456789RexBloomer12.00Bloomer, Rex

  • Status duing execution:
  • Initial state: [B223456789, Rex] RowState: Added
    Version: Original doesn't not exist.
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex

    Executing LoadDataRow(...)
    Column 'EmpId' is constrained to be unique.  Value 'B223456789' is already present.
    System.Data.ConstraintException
    at System.Data.UniqueConstraint.CheckConstraint(DataRow row, DataRowAction action) at System.Data.DataTable.RaiseRowChanging(DataRowChangeEventArgs args, DataRow eRow, DataRowAction eAction, Boolean fireEvent) at System.Data.DataTable.SetNewRecordWorker(DataRow row, Int32 proposedRecord, DataRowAction action, Boolean isInMerge, Int32 position, Boolean fireEvent, Exception& deferredException) at System.Data.DataTable.InsertRow(DataRow row, Int32 proposedID, Int32 pos, Boolean fireEvent) at System.Data.DataTable.LoadRow(Object[] values, LoadOption loadOption, Index searchIndex) at System.Data.DataTable.LoadDataRow(Object[] values, LoadOption loadOption) ...

    After error: [B223456789, Rex] RowState: Added
    Version: Original doesn't not exist.
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex


Primary key applied, no AcceptChanges before or after LoadDataRow
No error! The last row is updated.

  • Resulted DataTable:
  • EmpIdFirstNameLastNameSalaryLastName and FirstName
    A123456789BettyeWilliams11.00Williams, Bettye
    B223456789DeniseMiller13.00Miller, Denise

  • Status duing execution:
  • Initial state: [B223456789, Rex] RowState: Added
    Version: Original doesn't not exist.
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex

    Executing LoadDataRow(...)
    After LoadDataRow: [B223456789, Denise] RowState: Unchanged
    Version: Original Value: Denise
    Version: Current Value: Denise
    Version: Proposed doesn't not exist.
    Version: Default Value: Denise


No primary key, AcceptChanges before LoadDataRow
Expect errors [System.Data.UniqueConstraint.CheckConstraint]!
The last row remains unchanged.

  • Resulted DataTable:
  • EmpIdFirstNameLastNameSalaryLastName and FirstName
    A123456789BettyeWilliams11.00Williams, Bettye
    B223456789RexBloomer12.00Bloomer, Rex

  • Status duing execution:
  • Initial state: [B223456789, Rex] RowState: Added
    Version: Original doesn't not exist.
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex

    Apply AcceptChanges(): [B223456789, Rex] RowState: Unchanged
    Version: Original Value: Rex
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex

    Executing LoadDataRow(...)
    Column 'EmpId' is constrained to be unique.  Value 'B223456789' is already present.
    System.Data.ConstraintException
    at System.Data.UniqueConstraint.CheckConstraint(DataRow row, DataRowAction action) at System.Data.DataTable.RaiseRowChanging(DataRowChangeEventArgs args, DataRow eRow, DataRowAction eAction, Boolean fireEvent) at System.Data.DataTable.SetNewRecordWorker(DataRow row, Int32 proposedRecord, DataRowAction action, Boolean isInMerge, Int32 position, Boolean fireEvent, Exception& deferredException) at System.Data.DataTable.InsertRow(DataRow row, Int32 proposedID, Int32 pos, Boolean fireEvent) at System.Data.DataTable.LoadRow(Object[] values, LoadOption loadOption, Index searchIndex) at System.Data.DataTable.LoadDataRow(Object[] values, LoadOption loadOption) ...

    After error: [B223456789, Rex] RowState: Unchanged
    Version: Original Value: Rex
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex


Primary key applied, AcceptChanges before LoadDataRow
No error! The last row is updated.

  • Resulted DataTable:
  • EmpIdFirstNameLastNameSalaryLastName and FirstName
    A123456789BettyeWilliams11.00Williams, Bettye
    B223456789DeniseMiller13.00Miller, Denise

  • Status duing execution:
  • Initial state: [B223456789, Rex] RowState: Added
    Version: Original doesn't not exist.
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex

    Apply AcceptChanges(): [B223456789, Rex] RowState: Unchanged
    Version: Original Value: Rex
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex

    Executing LoadDataRow(...)
    After LoadDataRow: [B223456789, Denise] RowState: Unchanged
    Version: Original Value: Denise
    Version: Current Value: Denise
    Version: Proposed doesn't not exist.
    Version: Default Value: Denise


No primary key, LoadDataRow in conjunction with Begin/EndLoadData
Expect errors [System.Data.DataTable.EnableConstraints()]!
Duplicate rows are found.

  • Resulted DataTable:
  • EmpIdFirstNameLastNameSalaryLastName and FirstName
    A123456789BettyeWilliams11.00Williams, Bettye
    B223456789RexBloomer12.00Bloomer, Rex
    B223456789DeniseMiller13.00Miller, Denise

  • Status duing execution:
  • Initial state: [B223456789, Rex] RowState: Added
    Version: Original doesn't not exist.
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex

    BeginLoadData(): turn off notification/constraints/indexing.

    Executing LoadDataRow(...)
    After LoadDataRow: [B223456789, Denise] RowState: Unchanged
    Version: Original Value: Denise
    Version: Current Value: Denise
    Version: Proposed doesn't not exist.
    Version: Default Value: Denise

    EndLoadData(): turn on validation, constraints, etc.

    Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints.
    System.Data.ConstraintException
    at System.Data.DataTable.EnableConstraints() at System.Data.DataTable.set_EnforceConstraints(Boolean value) at System.Data.DataTable.EndLoadData() ...

    After error: [B223456789, Rex] RowState: Added
    Version: Original doesn't not exist.
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex


Primary key applied, LoadDataRow in conjunction with Begin/EndLoadData
No error! The last row is updated.

  • Resulted DataTable:
  • EmpIdFirstNameLastNameSalaryLastName and FirstName
    A123456789BettyeWilliams11.00Williams, Bettye
    B223456789DeniseMiller13.00Miller, Denise

  • Status duing execution:
  • Initial state: [B223456789, Rex] RowState: Added
    Version: Original doesn't not exist.
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex

    BeginLoadData(): turn off notification/constraints/indexing.

    Executing LoadDataRow(...)
    After LoadDataRow: [B223456789, Denise] RowState: Unchanged
    Version: Original Value: Denise
    Version: Current Value: Denise
    Version: Proposed doesn't not exist.
    Version: Default Value: Denise

    EndLoadData(): turn on validation, constraints, etc.

    [B223456789, Denise] RowState: Unchanged
    Version: Original Value: Denise
    Version: Current Value: Denise
    Version: Proposed doesn't not exist.
    Version: Default Value: Denise


Primary key applied, LoadDataRow in conjunction with Begin/EndLoadData, ApplyChanges before BeginLoadData
No error! The last row is updated.

  • Resulted DataTable:
  • EmpIdFirstNameLastNameSalaryLastName and FirstName
    A123456789BettyeWilliams11.00Williams, Bettye
    B223456789DeniseMiller13.00Miller, Denise

  • Status duing execution:
  • Initial state: [B223456789, Rex] RowState: Added
    Version: Original doesn't not exist.
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex

    Apply AcceptChanges(): [B223456789, Rex] RowState: Unchanged
    Version: Original Value: Rex
    Version: Current Value: Rex
    Version: Proposed doesn't not exist.
    Version: Default Value: Rex

    BeginLoadData(): turn off notification/constraints/indexing.

    Executing LoadDataRow(...)
    After LoadDataRow: [B223456789, Denise] RowState: Unchanged
    Version: Original Value: Denise
    Version: Current Value: Denise
    Version: Proposed doesn't not exist.
    Version: Default Value: Denise

    EndLoadData(): turn on validation, constraints, etc.

    [B223456789, Denise] RowState: Unchanged
    Version: Original Value: Denise
    Version: Current Value: Denise
    Version: Proposed doesn't not exist.
    Version: Default Value: Denise

Saturday, May 8, 2010

Extract File Extension and Check Image Format

[ Intention | Requirements | Discussion and Implementation | Final Code Snippets ]

Intention [top]

Once in a while, we all may need to extract the file extension from a file name. In the past, when I was doing it in Java, I used to use the String.lastIndexOf() to search for the last period in the filename and then extract the rest of the substring. We can apply the same idea in .NET using String.LastIndexOf() as well. However, .NET provides a single static method call; it makes everything a lot easier. However, this static method internal implementation is not using regular expression to extract the file extension. Yesterday, I was browsing around my old code and thinking that I would like to use regular expression to capture the file extension. Thus, I pick the portion of my file upload program for conversion. First, I will start with the requirements for this file upload portion and then go into the detail discussion. Finally I will present the complete code snippets. In this exercise, I will also show you how to check the image format.

Requirements [top]

  1. Use regular expression to capture or extract the file extension from the file name but the leading period (.) of the resulted file extension must be trimmed off. For example, .txt becomes txt.
  2. A file extension cannot contain spaces.
  3. Save the uploaded file if only if the file extension is one of the listed extensions (see the list below) and the file must be one of the supported image formats.
  4. Supported file extensions are BMP, GIF, PNG, TIFF, JPG, and JPEG.
  5. Supported image formats are BMP, GIF, PNG, TIFF and JPEG. They are also corresponding to the above file extensions

Discussion and Implementation [top]

There are a few ways to extract a file extension from a file name. One of the simple ways is to use System.IO.Path.GetExtension() method by passing the file name as a parameter, e.g.,

   System.IO.Path.GetExtension("abc.txt")

In this example, .txt is the extracted file extension and it always comes with a leading period (.). In order to fit our 1st requirement, we could remove the leading period from the resulted file extension. Unfortunately, the requirement binds us to use regular expression. Thus, the regular expression should look like the following (non-named capturing):

      \.([^.]+)$

According to the 2nd requirement (the extension cannot contain spaces), the previous regular expression is revised and becomes:

      \.([^(\s|.)]+)$

In C#, we can do the following to fulfill the #1 and the #2 requirements:

      String pattern = @"\.([^(\s|.)]+)$";        
      String fileExt = null;

      Regex r = new Regex(pattern);
      Match m = r.Match(filename);
      if (m.Success) {
        fileExt = m.Groups[1].Value;
      }

As we can see, the captured text is always placed inside the group 1 (at index 1), not 0. What if we have many captured groups? It could be hard to remember which one is what. Luckily, .NET supports name capturing. It greatly helps in coding and back-reference. In this example, the requirement is simple and we don't have to use named capture. But to exercise this named capture feature, we could revise the regular expression a bit and then reference the name in our code. Let's say that the captured text name is called ext. The revised code snippet becomes:

      String pattern = @"\.(?<ext>[^(\s|.)]+)$";        
      String fileExt = null;

      Regex r = new Regex(pattern);
      Match m = r.Match(filename);
      if (m.Success) {
        fileExt = m.Groups["ext"].Value; 
      }

A part of the third requirement is to check the resulted file extension against our supported file extension list. We can continuously get help from regular expression. Let's define our pattern for matching. In C#, we can write this:

      String SupportedImageExtPatterns = "^(BMP|GIF|PNG|TIFF|JPE?G)$";

To check the resulted file extension against the list, in C#, we can implement this way:

      Match m1 = Regex.Match(fileExt, 
                             SupportedImageExtPatterns,
                             RegexOptions.IgnoreCase);
      if (m1.Success) {
        ...
      }
or using one single statement,
      if (Regex.Match(fileExt, 
                      SupportedImageExtPatterns,
                      RegexOptions.IgnoreCase).Success) {  
          ...
      }

How to check the file is one of the supported image format? Since the file is uploaded via HTTP, the file could be anything. For this matter, we first need to confirm if the file is an image by referencing to the file's Stream object and then try to convert it to an image. If we get an ArgumentException, it is not an image. Let's say the file upload object is called FileUpload1. In C#, we can write the following to execute the idea.

      System.Drawing.Image theImage = null;
      try {
        theImage = System.Drawing.Image.FromStream(FileUpload1.PostedFile.InputStream);
      }
      catch (System.ArgumentException) {  // not an image
        ...
      }
After we've confirmed that the file is an image, we can go ahead to check the image format against our list with the help of the Equals() method of System.Drawing.Imaging.ImageFormat. For convenience, I group all the required System.Drawing.Imaging.ImageFormat objects together in an array so that I can iterate through the array for checking.
       System.Drawing.Imaging.ImageFormat[] SupportedImageFormats = { 
             System.Drawing.Imaging.ImageFormat.Bmp,      
             System.Drawing.Imaging.ImageFormat.Gif,      
             System.Drawing.Imaging.ImageFormat.Png,
             System.Drawing.Imaging.ImageFormat.Tiff,
             System.Drawing.Imaging.ImageFormat.Jpeg      
       };

The code snippet for checking image format in C# is illustrated below:
       System.Drawing.Imaging.ImageFormat[] SupportedImageFormats = { 
         System.Drawing.Imaging.ImageFormat.Bmp,      
         System.Drawing.Imaging.ImageFormat.Gif,      
         System.Drawing.Imaging.ImageFormat.Png,
         System.Drawing.Imaging.ImageFormat.Tiff,
         System.Drawing.Imaging.ImageFormat.Jpeg      
       };

       System.Drawing.Image theImage = null;
       try {
         theImage = System.Drawing.Image.FromStream(FileUpload1.PostedFile.InputStream);

         for (int i=0; i < SupportedImageFormats.Length; i++) {        
           if (theImage.RawFormat.Equals(SupportedImageFormats[i])) {
             ...
             break;
           }
         }
         ...

       }
       catch (System.ArgumentException) {  // not an image
         ...
       }

As soon as we confirm that the file is an image and it is also one of our expected formats, we can simply use the FileUpload object SaveAs() method by passing the absolute pathname. Let's say the directory to save is called Uploads. The statement may look something like below:

   FileUpload1.SaveAs(Server.MapPath("~/Uploads/") + FileUpload1.FileName);
Up to here, our mission is accomplished from extracting the file extension, checking image format to saving the file. The complete code snippets are presented in the next section.

Final Code Snippets [top]

The followings are two pieces of code snippets summarized for the above discussions. The difference between these two pieces of code is: one is using non-named capture to extract the file extension while the other is named capture. Other than that, everything is identical.

Using non-named capture to extract the file name [ Final Code Snippets | top ]

Note that
  1. the file upload control object is called FileUpload1, and
  2. the save directory is called Uploads and located at the root directory.
// declare the pattern for Requirement #1 and #2 to capture the file extension.
// the following pattern is using non-named capture.
String pattern = @"\.([^(\s|.)]+)$";        
String fileExt = null;

Regex r = new Regex(pattern);
Match m = r.Match(FileUpload1.PostedFile.FileName); 
if (m.Success) {
  // capture the file extension without the period
  // here we use non-named capture group
  fileExt = m.Groups[1].Value;

  // Requirement #4 - the supported file extensions
  String SupportedImageExtPatterns = "^(BMP|GIF|PNG|TIFF|JPE?G)$";

  if (Regex.Match(fileExt, 
                  SupportedImageExtPatterns,
                  RegexOptions.IgnoreCase).Success) {

    // Requirement #5 - the supported image formats 
    System.Drawing.Imaging.ImageFormat[] SupportedImageFormats = { 
          System.Drawing.Imaging.ImageFormat.Bmp,      
          System.Drawing.Imaging.ImageFormat.Gif,      
          System.Drawing.Imaging.ImageFormat.Png,
          System.Drawing.Imaging.ImageFormat.Tiff,
          System.Drawing.Imaging.ImageFormat.Jpeg      
    };

    System.Drawing.Image theImage = null;
    try {
      theImage = System.Drawing.Image.FromStream(FileUpload1.PostedFile.InputStream);
    
      for (int i=0; i < SupportedImageFormats.Length; i++) {        
        if (theImage.RawFormat.Equals(SupportedImageFormats[i])) {
           // Requirement #3 - save the file only if it is our expected image format.
           FileUpload1.SaveAs(Server.MapPath("~/Uploads/") + FileUpload1.FileName);
           break;
        }
      }      
    }
    catch (System.ArgumentException) {  // not an image
      ...  
    }
  }
}

Using named capture to extract the file name [ Final Code Snippets | top ]

Note that
  1. the file upload object is called FileUpload1, and
  2. the save directory is called Uploads and located at the root directory.
// declare the pattern for Requirement #1 and #2 to capture the file extension.
// the following pattern is using named capture.
String pattern = @"\.(?<ext>[^(\s|.)]+)$";        
String fileExt = null;

Regex r = new Regex(pattern);
Match m = r.Match(FileUpload1.PostedFile.FileName);
if (m.Success) {
  // capture the file extension without the period
  // here we use named capture group
  fileExt = m.Groups["ext"].Value;

  // Requirement #4 - the supported file extensions
  String SupportedImageExtPatterns = "^(BMP|GIF|PNG|TIFF|JPE?G)$";

  if (Regex.Match(fileExt, 
                  SupportedImageExtPatterns,
                  RegexOptions.IgnoreCase).Success) {

    // Requirement #5 - the supported image formats 
    System.Drawing.Imaging.ImageFormat[] SupportedImageFormats = { 
          System.Drawing.Imaging.ImageFormat.Bmp,      
          System.Drawing.Imaging.ImageFormat.Gif,      
          System.Drawing.Imaging.ImageFormat.Png,
          System.Drawing.Imaging.ImageFormat.Tiff,
          System.Drawing.Imaging.ImageFormat.Jpeg      
    };

    System.Drawing.Image theImage = null;
    try {
      theImage = System.Drawing.Image.FromStream(FileUpload1.PostedFile.InputStream);
    
      for (int i=0; i < SupportedImageFormats.Length; i++) {        
        if (theImage.RawFormat.Equals(SupportedImageFormats[i])) {
           // Requirement #3 - save the file only if it is our expected image format.
           FileUpload1.SaveAs(Server.MapPath("~/Uploads/") + FileUpload1.FileName);
           break;
        }
      }      
    }
    catch (System.ArgumentException) {  // not an image
      ...  
    }
  }
}

Wednesday, April 7, 2010

Facebook Privacy Setting for Wall Posts by Friends

Also see the update on Jan 5, 2011.


Facebook has been changing a lot since this March and they still keep changing. Have you ever noticed the above setting in the red box?

You can find this setting at your personal profile page. Go to your profile, locate the "Share" button. Right below it, click on "Settings," you will find the above settings circling by the red box.

If you change the setting for "Who can see posts made by friends?" to "Only Me," the check box for "Posting Ability" will be grayed out and become unchecked. It means no one or application can post anything to your wall. Unfortunately you won't notice this change unless you immediately refresh the page and then go back to the same location to check on it. Or you may know this problem when someone notifies you.

These above two settings are supposedly corresponding to the settings at your privacy settings page. Again, it is confusing. After the changes made from your profile page, if you go and check your privacy settings page, you will find this confusing settings as shown in the following picture.


The check box for "Friends can post on my Wall" is still on (checked) while "Posts by Friends - Control who can see posts by your friends on your profile" is set to "Only Me."

Because the second setting is set to "Only Me," no one but you can post to your wall. Thus, if you allow your friends to post something to your wall, please make sure "... [W|w]ho can see posts made by ... friends... " is set appropriate in your profile page or your privacy settings page.

I personally don't understand why Facebook still doesn't want to change or amend this wording "... who can see posts made by ... friends?" to make things clear.

Thursday, March 25, 2010

How to make UTF-8 as default encoding in Notepad++ manually

The following information applies to version 5.1 up to the current latest version 5.6.8. It may apply to the future versions. However, if you're using the latest one (5.6.8), the GUI now provides a nice setting for you to change (Settings -> Preferences -> New Document/Default Directory). If you use the GUI to change the settings, the following manual method may not work. I don't know where another configuration files are stored.

Important: Don't use the same version of Notepad++ to edit any its configuration files. Otherwise, all your changes or modifications will be lost when you exit.

Note that I use Notepad++ zip version and do the manual installation instead of using the executable installer. Thus, your installed file structure may be different from mine if you're using installer.

  • Go to the location where you install your Notepad++ and you should see two folders, ansi and unicode.

    Each folder represents a distinct version. The Unicode version is mainly to support Unicode characters in paths. Please see here to learn more about these two versions.
  • Go in either ANSI or Unicode version folder where you may use to launch your Notepad++.
  • Open the file called config.xml. For the newest version, this file doesn't exist at the beginning but config.model.xml is provided. Make a copy from config.model.xml and then rename it to config.xml.
  • Locate the following line:
    <GUIConfig name="NewDocDefaultSettings" format="0" encoding="1" lang="0" openAnsiAsUTF8="no" />
    
  • Set encoding to 4 for UTF-8. For other encodings, see the table below or the comment inside the file.
    <GUIConfig name="NewDocDefaultSettings" format="0" encoding="4" lang="0" openAnsiAsUTF8="no" />
    
    0ANSI
    1UCS2 BIG
    2UCS2 SMALL
    3UTF 8
    4UTF 8 without BOM
  • Relaunch the Notepad++.

Monday, January 11, 2010

Thinking to extend my MagicJack service to 5 years

magic jack I have been using MagicJack almost for a year. I am thinking to extend the service to 5 years. Unfortunately, the charge of 5-year service plan has been increased from $59.99 to $69.99. If I have have know this, I could have extended it earlier to save my $10.00. Still, this 5-year plan deal is better than the one provided by AT&T, Time Warner or other phone service companies. The most importance is that I am satisfied with their phone quality but I have to bear with their poor support service including Web one.


Note that beginning of this post, I switched to use the image hosting service from ImageShack instead of PhotoBucket because PhotoBucket has imposted a storage limit to free accounts.

Monday, October 26, 2009

Why inner DIV doesn't inherit background color

What situation will make an inner DIV not inherit the background color of the outer DIV? It usually happens when CSS or HTML style's float attribute exists. Considering the following HTML,
<html>
<body style="background-color:#F8E0EC;">
<div style="background-color:#fff;padding:20px;border:10px solid blue;">        
  <div style="float:left;width:330px;border: 1px dotted red;">
      <p>
        <strong>When:</strong>          
        12/5/2009        
        <strong>@</strong>
        3:30 PM
      </p>
      <p>
        <strong>Where:</strong>
        5 main street
        USA
      </p>
      <p>
        <strong>Description:</strong>
        test
      </p>
      <p>
        <strong>Contact:</strong>
        425-555-1212
      </p>   
  </div>   
</div> 
</body>
</html>
The picture will look like this:
inner div floats outside
As you can see, most inner DIV text are sitting outside the blue box (outer DIV). If you take out the float attribute, everything will work fine. The reason of using float attribute is that you may want to have another DIV sit side-by-side together. In this situation, you need to put
   <div style="clear:both"></div> 
at the end of the inner DIV, just before closing the outer DIV. In my example, I will continue to use only one inner DIV. You can test it yourself with two.
<html>
<body style="background-color:#F8E0EC;">
<div style="background-color:#fff;padding:20px;border:10px solid blue;">        
  <div style="float:left;width:330px;border: 1px dotted red;">
      <p>
        <strong>When:</strong>          
        12/5/2009       
        <strong>@</strong>
        3:30 PM
      </p>
      <p>
        <strong>Where:</strong>
        5 main street
        USA
      </p>
      <p>
        <strong>Description:</strong>
        test
      </p>
      <p>
        <strong>Contact:</strong>
        425-555-1212
      </p>   
  </div>

  <div style="clear:both"></div>
   
</div> 
</body>
</html>

inner div floats outside
Now the problem is fixed.

Saturday, October 24, 2009

Key Notes for Complie, Install, and Using OpenSSL on Windows

Ref Docs: Generate Private Key | Generate Certificate | config | openssl | openssl req | openssl ca

I downloaded three versions of OpenSSL and have successfully compiled both versions 0.9.8h and 0.9.8k. But the compilation failed on the latest beta version 1.0.0-beta3. In this document, I will describe how I compile, install and use OpenSSL into IIS on Windows. Note that the part using/configure OpenSSL is missing in this article. I haven't completed it in my writing. I was distracted by something else while I was working on this article. All my notes are still in my local computer. After a while, I completely forget about it. Since it is just for my own notes or references, I decide to leave it as-is. If I upgrade my OpenSSL, I may update this info as needed.

Tools needed:
  • Cygwin, or GNU tar and gzip: If you don't have cygwin, I would recommend to install it. You will find a lot of useful UNIX utilities such as tar and gzip. For openssl purpose, you need both tar and gzip to unpack the openssl-<version>.tar.gz file. Don't use WinZip, WinRAR or similar to uncompress the file. Or most likely you will have problems in compilation. You can use GNU tar and gzip instead if you have them. But I have some troubles using them.
  • MinGW: It is optional unless you compile openssl under cygwin with error(s). MinGW can compile source under a DOS command prompt. For a unknown reason, I cannot compile openssl under cygwin but I can compile it under DOS with MinGW. I also cannot compile it with VC++ either.

Compilation

The followings are the steps I was taking to get the job done and MinGW is the compiler.
  1. Uncompress the file using tar and gzip. You can do it under either DOS or Cygwin Bash Shell enviornment.
    tar zxvf openssl-x.x.x.tar.gz

    With the z option, tar will automatically involve gzip to work together. Thus you must have gzip around and they both must sit in the same directory.
  2. After the file extraction, look for INSTALL.W32 file for the detailed Windows compilation instructions
  3. Ensure MinGW's bin directory is in the PATH environment. Or you can do the following at the command prompt, assuming your MinGW installation directory is at c:\mingw.
    set PATH=c:\mingw\bin;%PATH%"
  4. Change directory into OpenSSL-x.x.x directory, for example,
    cd c:\openssl-0.9.8k
  5. Type the following command to compile:
    ms\mingw32
  6. The compilation will take a while. When it is done successfully, it will end with the following two lines:
    Generating the DLLs and input libraries
    Done compiling OpenSSL
  7. Two DLL's files ( libeay32.dll and libssl32.dll ) are found in the root directory (e.g., c:\openssl-0.9.8k). MinGW also produced two additional directories: out and outinc.

    openssl.exe and other executable files are found in out.

    outinc contains all the headers files.

After Compilation

There is no actual openssl installation. As openssl claims, if you compile it under cygwin, the compiled version will be placed under cygwin directory at /usr/local/ssl. In my case (because I use MinGW for compilation) , I have to repackage the files and the directories myself.
  • Create the following directory tree:
    openssl dir
  • Copy files (assuming the above step is created at c:\):
         copy out\*  c:\openssl\bin
         copy outinc\openssl\*  c:\openssl\include\openssl
         copy out32dll\libeay32.dll c:\openssl\lib
         copy out32dll\libssl32.dll c:\openssl\lib
         copy apps\openssl.cnf  c:\openssl\config
    

Master Configuration File Location

The master openssl.cnf is located inside the apps directory.

The openssl configuration file name is openssl.cnf, which is expected to be found at /usr/local/ssl/ (unix file path style). If you are using cygwin, this ( /usr/local/ssl/openssl.cnf) should be under your cygwin directory. Unfortunately, I cannot compile it under cygwin. Again, I am using mingw as my compiler. With it, the master configuration file is located inside the apps directory.

Possible Issue

When you answer Y to sign the certificate/request again, you may have the following error:
Sign the certificate? [y/n]:y
failed to update database
TXT_DB error number 2

Solution: You cannot have two certificates that look the same. To fix this, there are two options:
  1. You can remove the line in the database (index.txt) or replace the index.txt with an empty one. Or
  2. you can revoke the previous certificate, e.g, openssl ca -revoke myCA.cer