Visual Studio Data : VS2008

Easier Sync

Yang Cao — Sat, 26 Sep 2009 17:09:28 GMT

If you’ve been using Data Source Configuration Wizard since Visual Studio 2005, you’ll notice that with Visual Studio 2008 Service Pack 1, there’s a “small” change – on Choose Your Database Objects page, a new checkbox would allow you to “enable local database caching”:

This checkbox will be available if the current connection is to a SQL Server database. The technology behind is Microsoft Synchronization Service for ADO.NET, which lets you synchronize data among any kind of data sources that support ADO.NET. If your client application does not always have a network connection, or if the application requires good data loading performance regardless of the network condition, you should consider using this feature to create a local copy of the data on the client and have your DataSet work against this local data cache. Another benefit is scalability. You can use local database caches for read-only data or rarely-changing data to increase database scalability. For more information of the technology, please click here.

If this checkbox is checked, the next page will let you choose among all the data tables in the DataSet, which tables you’d like to cache.

Something worth mentioning on this page are:

Not all tables can be synchronized. Tables that don’t have a primary key, for example, cannot be synchronized with the wizard.
There’re two synchronization modes: Incremental mode synchronizes only changes that were made on the server since the last synchronization. Snapshot mode replaces the whole locally cached table with the current table on the server.
If you’re using SQL Server 2008, another checkbox will let you take advantage of the change tracking feature. With this feature enabled, for incremental mode of synchronization, you don’t need to create timestamp column or tombstone table [BAM3] to track all the changes since the last synchronization (timestamp columns will track each data item’s insert and update time; a tombstone table will track each data item’s delete time) . SQL Server 2008 will do it for you.

After selecting these settings, the Data Sources Configuration Wizard will prompt you to generate and run a script if you have tables with incremental mode synchronization. The script will help you turn on the SQL Server 2008 change tracking feature, or if you didn’t enable this feature, the script will help you generate all the necessary columns or table to track insert, update and delete operations since last sync.

Now a DataSet, a sync file, and a local database cache are added into the project. The DataSet will have two connection strings, one to the remote database, another to the local database cache. The application works fine at first because the server tables and client tables have identical data. However, of course, sooner or later, the two databases will be out of sync. To synchronize the local database cache with the remote one is pretty simple: call Synchronize method of the SyncAgent. For more information, please check this walkthrough: Creating an Occasionally Connected Application by Using the Data Source Configuration Wizard.

Please pay attention if you reopen the Data Source Configuration Wizard and make updates to the synchronization configuration. It might cause the DataSet to be regenerated. If you have any customization to the DataSet, please remember to back it up beforehand.

Enjoy coding and syncing!

Cheers!

Writing Event Handler for controls in a DataRepeaterItem

John Chen — Wed, 09 Sep 2009 01:54:00 GMT

In the MSDN Visual Basic Power Packs forum, I had an embarrassing reply on a DataRepeater event handling question, in which the user asked why his event handling code did not work. Here is the original question:

“I want to be able to resize a textbox when a user clicks on a textbox within a datarepeater. So the textbox will start out as a single line, but would expand to be multiline to better allow the user to enter text. When the user's mouse leaves the textbox I want it to return to the original size. I tried changing the textbox.height, but nothing happens. Any help is appreciated.”

By looking at the question, I guessed that the user might forget to set the TextBox.MultiLine to true while trying to change the height. Without hesitation, I replied a sample code as below:

Private Sub TextBox1_MouseEnter(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox1.MouseEnter

Me.TextBox1.Multiline = True

Me.TextBox1.Height = 50

End Sub

Private Sub TextBox1_MouseLeave(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox1.MouseLeave

Me.TextBox1.Multiline = False

End Sub

Code Sample 1

The user then replied back that the Multiline was not the problem. My code did not work! What is happening?

The DataRepeater control is very intuitive to use and is close to the WYSIWYG experience. However, we need to remember that at run time, the repeater items are cloned using the repeater item template. At design time, we are working on the repeater item template. At run time, several sets of new controls are created to serve as the display of the visible repeater items. Public properties of a control are copied during the cloning process, so do the event handlers. If Button1 is a button in the data repeater item template, code sample 2 below works perfectly.

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

MessageBox.Show("Hello")

End Sub

Code Sample 2

Now let’s take a look on code sample 1, the event handler is cloned and so the code will be called when the mouse enters or leaves the TextBox. However, the code does not work as expected because TextBox1 refers to the template version of the TextBox, which is hidden at run time. The underline TextBox that triggers the event is the cloned version of the TextBox and in the context it is the sender object. So I modified code sample 1 to code sample 3, accessing TextBox1 through the sender object. Tested and worked.

Private Sub TextBox1_MouseEnter(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox1.MouseEnter

Dim txtBox As TextBox = TryCast(sender, TextBox)

If (txtBox IsNot Nothing) Then

txtBox.Multiline = True

txtBox.Height = 50

End If

End Sub

Private Sub TextBox1_MouseLeave(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox1.MouseLeave

Dim txtBox As TextBox = TryCast(sender, TextBox)

If (txtBox IsNot Nothing) Then

txtBox.Multiline = False

End If

End Sub

Code Sample 3

I hope this example can help you better understand how the DataRepeater works. Keep in mind that the controls in the repeater item area we work on at design time are used for templates and we should not use them at run time unless you want to change the properties for all repeater items (please see Gavin’s blog: How to Change Appearance of all DataRepeater Items at Run Time). If you need to work on an individual control on a repeater item, use the sender object (as in code sample 1) and then get its parent and siblings if necessary. You can also get access to a DataRepeaterItem, which inherits from Panel control, and then you can access to all the controls in the control’s hierarchical structure. To illustrate this, I would like to change the original forum question to resize the TextBox whenever the current repeater item changes. Code sample 4 below is my solution.

Dim lastModifiedTxtBox As TextBox = Nothing

Private Sub DataRepeater1_CurrentItemIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles DataRepeater1.CurrentItemIndexChanged

' Get The TextBox1 from Me.DataRepeater1.CurrentItem

Dim txtBox As TextBox = Me.DataRepeater1.CurrentItem.Controls("TextBox1")

If (txtBox IsNot Nothing) Then

txtBox.Multiline = True

txtBox.Height = 50

End If

If (Not Object.ReferenceEquals(txtBox, lastModifiedTxtBox)) Then

If (lastModifiedTxtBox IsNot Nothing) Then

lastModifiedTxtBox.Multiline = False

End If

lastModifiedTxtBox = txtBox

End If

End Sub

Code Sample 4

In code sample 4, I use DataRepeater.CurrentItem property to get the current DataRepeaterItem and then I use Control.Controls property to return the cloned version of the TextBox1 in the current DataRepeaterItem. Notice that the cloned version of the TextBox is named as “TextBox1” as well, this is allowed at run time as long as it is named uniquely under the parent control (the DataRepeaterItem, in the context). Because there is no CurrentItemIndexChanging event, I use lastModifiedTextBox to remember the last modified TextBox and restore its state when necessary.

Lastly, I would like to point out again (as I have in my previous post) that the DataRepeater control applies a virtualization technique to display the data. So at run time, only a few DataRepeaterItems are created for display purpose. These DataRepeaterItems are reused by all data rows when they enter the visible range. So it is important that if you set a property on a control based on a data row. You may want to reset it appropriately when the data row is out of the visible range as the control will be reused by other data rows. Let me change the task again to only resize the TextBox1 for the first data row, and I will use DataRepeater.DrawItem event this time to get the DataRepeaterItem.

Private Sub DataRepeater1_DrawItem(ByVal sender As Object, ByVal e As Microsoft.VisualBasic.PowerPacks.DataRepeaterItemEventArgs) Handles DataRepeater1.DrawItem

Dim txtBox As TextBox = e.DataRepeaterItem.Controls("TextBox1")

If (txtBox IsNot Nothing) Then

If (e.DataRepeaterItem.ItemIndex = 0) Then

' Special treatment for the first data row

txtBox.Multiline = True

txtBox.Height = 50

Else

' Reset to its original state..

' Without this line, the result will be unexpected.

txtBox.Multiline = False

End If

End Sub

Code Sample 5

In code sample 5 above, if I omit the line to reset the txtBox.Multiline = False, you will see unexpected result after scrolling the data repeater up and down for a few times. See an illustration in picture 1 below.

Picture 1

In conclusion, writing event handler for a control in a DataRepeaterItem can be as straightforward as in a plain form like code sample 2. However, when individual control is needed, you need to make sure to get the correct run time control and remember to reset its property after the use.

How to Workaround Sorting Errors when Updating Self-Referencing DataSet Tables with Visual Studio 2008 SP1

Gavin Fu — Sat, 05 Sep 2009 07:14:00 GMT

Hierarchical update is an important feature of typed dataset that refers to the process of saving updated data back to a database while maintaining referential integrity rules. This feature is enhanced in Visual Studio 2008 by introducing a TableAdapterManger component to manage all TableApdaters in a typed dataset. When updating related tables, TableAdapterManager uses foreign-key relationships to determine the correct order to send Insert, Update, and Delete commands from a dataset to the database without violating the foreign-key constraints (referential integrity) in the database.

TableAdpaterManager is automatically generated when you create a typed-dataset in a project with Hierarchical Update enabled (For more information, see How to Enable and Disable Hierarchical Update), and it could greatly reduce the code to save data to multiple related tables. Users just need to call TableAdpaterManager.UpdateAll(DataSet). You could see how easy it is to use this class in “Sample Code Snippet to Update the Database” section of this article. However, when updating self-referencing tables, TableAdpaterManager has some defects in determining the correct order of affected rows, which could cause constraint violation errors when committing the changes to database. We have noticed this problem and are investigating how to resolve it. I’ll explain the idea of the solution and how to work around this issue with Visual Studio 2008 SP1.

What the Problem is

Sample Table

Suppose that you have a self-referencing table named Temp with three columns and a foreign-key relationship.

Table Definition:

Foreign-Key Relation:

Generated Typed-DataSet Code Snippet

Suppose you add a typed-dataset (say, dataset1) to your application, and drag-drop the Temp table from Server Explorer to the dataset designer, Visual Studio will generate code of the typed-dataset for you. Below is the code snippet that is related to this topic.

[C#]

public partial class TableAdapterManager : global::System.ComponentModel.Component {

public virtual int UpdateAll(DataSet1 dataSet) {

. . . . . .

this.UpdateInsertedRows(dataSet, allAddedRows));

. . . . . .

this.UpdateDeletedRows(dataSet, allChangedRows));

. . . . . .

}

private int UpdateInsertedRows(DataSet1 dataSet, global::System.Collections.Generic.List<global::System.Data.DataRow> allAddedRows) {

. . . . . .

this.SortSelfReferenceRows(addedRows, dataSet.Relations["FK_Temp_Temp"], false);

. . . . . .

}

private int UpdateDeletedRows(DataSet1 dataSet, global::System.Collections.Generic.List<global::System.Data.DataRow> allChangedRows) {

. . . . . .

this.SortSelfReferenceRows(addedRows, dataSet.Relations["FK_Temp_Temp"], true);

. . . . . .

}

protected virtual void SortSelfReferenceRows(global::System.Data.DataRow[] rows, global::System.Data.DataRelation relation, bool childFirst) {

global::System.Array.Sort<global::System.Data.DataRow>(rows, new SelfReferenceComparer(relation, childFirst));

}

private class SelfReferenceComparer : object, global::System.Collections.Generic.IComparer<global::System.Data.DataRow> {

private global::System.Data.DataRelation _relation;

private int _childFirst;

. . . . . .

public int Compare(global::System.Data.DataRow row1, global::System.Data.DataRow row2) {

if (object.ReferenceEquals(row1, row2)) {

return 0;

}

if ((row1 == null)) {

return -1;

}

if ((row2 == null)) {

return 1;

}

// Is row1 the child or grandchild of row2

if (this.IsChildAndParent(row1, row2)) {

return this._childFirst;

}

// Is row2 the child or grandchild of row1

if (this.IsChildAndParent(row2, row1)) {

return (-1 * this._childFirst);

}

return 0;

}

[VB]

Partial Public Class TableAdapterManager

Inherits Global.System.ComponentModel.Component

Public Overridable Function UpdateAll(ByVal dataSet As DataSet1) As Integer

. . . . . .

Me.UpdateInsertedRows(dataSet, allAddedRows)

. . . . . .

Me.UpdateDeletedRows(dataSet, allChangedRows)

. . . . . .

End Function

Private Function UpdateInsertedRows(ByVal dataSet As DataSet1, ByVal allAddedRows As Global.System.Collections.Generic.List(Of Global.System.Data.DataRow)) As Integer

. . . . . .

Me.SortSelfReferenceRows(addedRows, dataSet.Relations("FK_Temp_Temp"), False)

. . . . . .

End Function

Private Function UpdateDeletedRows(ByVal dataSet As DataSet1, ByVal allChangedRows As Global.System.Collections.Generic.List(Of Global.System.Data.DataRow)) As Integer

. . . . . .

Me.SortSelfReferenceRows(addedRows, dataSet.Relations("FK_Temp_Temp"), True)

. . . . . .

End Function

Protected Overridable Sub SortSelfReferenceRows(ByVal rows() As Global.System.Data.DataRow, ByVal relation As Global.System.Data.DataRelation, ByVal childFirst As Boolean)

Global.System.Array.Sort(Of Global.System.Data.DataRow)(rows, New SelfReferenceComparer(relation, childFirst))

End Sub

Private Class SelfReferenceComparer

Inherits Object

Implements Global.System.Collections.Generic.IComparer(Of Global.System.Data.DataRow)

Private _relation As Global.System.Data.DataRelation

Private _childFirst As Integer

. . . . . .

Public Function Compare(ByVal row1 As Global.System.Data.DataRow, ByVal row2 As Global.System.Data.DataRow) As Integer

Implements Global.System.Collections.Generic.IComparer(Of Global.System.Data.DataRow).Compare

If Object.ReferenceEquals(row1, row2) Then

Return 0

End If

If (row1 Is Nothing) Then

Return -1

End If

If (row2 Is Nothing) Then

Return 1

End If

'Is row1 the child or grandchild of row2

If Me.IsChildAndParent(row1, row2) Then

Return Me._childFirst

End If

' row2 the child or grandchild of row1

If Me.IsChildAndParent(row2, row1) Then

Return (-1 * Me._childFirst)

End If

Return 0

End Function

End Class

Sample Code Snippet to Update the Database

Then, you could update the table with the help of TableAdapterManager. Below is snippet of sample code to insert some rows to the self-referencing Temp table, and then delete them.

[C#]

DataSet1 ds = new DataSet1();

DataSet1.TempRow row1 = ds.Temp.AddTempRow(1, null, "Row 1");

DataSet1.TempRow row4 = ds.Temp.AddTempRow(4, null, "Row 4");

DataSet1.TempRow row2 = ds.Temp.AddTempRow(2, row1, "Row 2");

DataSet1.TempRow row3 = ds.Temp.AddTempRow(3, row4, "Row 3");

DataSet1TableAdapters.TableAdapterManager manager = new DataSet1TableAdapters.TableAdapterManager();

. . . . . .

manager.UpdateAll(ds); // Insert the rows

row1.Delete();

row2.Delete();

row3.Delete();

row4.Delete();

manager.UpdateAll(ds); // Delete the rows

[VB]

Dim ds As DataSet1 = New DataSet1

Dim row1 As DataSet1.TempRow = ds.Temp.AddTempRow(1, Nothing, "Row 1")

Dim row4 As DataSet1.TempRow = ds.Temp.AddTempRow(4, Nothing, "Row 4")

Dim row2 As DataSet1.TempRow = ds.Temp.AddTempRow(2, row1, "Row 2")

Dim row3 As DataSet1.TempRow = ds.Temp.AddTempRow(3, row4, "Row 3")

Dim manager As DataSet1TableAdapters.TableAdapterManager = New DataSet1TableAdapters.TableAdapterManager

manager.UpdateAll(ds) ' Insert the rows

row1.Delete()

row2.Delete()

row3.Delete()

row4.Delete()

manager.UpdateAll(ds) ' Delete the rows

What is the Problem and Why

From the code at the beginning of the post, we can see that TableAdapterManager uses System.Array.Sort<T>(T, IComparer<T>) to sort all rows before inserting them into or deleting them from database so that no violations to foreign-key constraints occur. The expected sorting result is: parent first for inserted rows, and child first for deleted rows. Take the sample code above for example, before calling SortSelfReferenceRows method, content of the array to insert is <R₁, R₄, R₂, R₃>. After calling the sorting method, R₁should come before R₂, and R₄ should come before R₃. Because R₁ is Parent of R₂, and R₄ is Parent of R₃. Sequence between two rows that do not have Parent-Child (or Grandparent-Grandchild, etc) relationships are undetermined, e.g., R₁ could come either before or after R₄.

For each pair <row1, row2> in the array to sort, SortSelfReferenceRows.Compare() will be called to determine their sequence in the output array. From the implementation of SortSelfReferenceRows.Compare, we could see that any two rows that do not have a Parent-Child (or Grandparent-Grandchild, etc) relationship are treated equal. This is OK if all possible row pairs are compared, e.g. < R₁, R₄>, < R₁, R₂>, < R₁, R₃>, < R₄, R₂>, < R₄, R₃>, < R₂, R₃> are all explicitly compared by passing them to SortSelfReferenceRows.Compare. However, System.Array.Sort is implemented using QuickSort, it does not compare every possible row pair. Instead, equation relationships of rows are treated transitive. For example, if < R₁, R₄>is compared and the result is R₁ == R₄, < R₄, R₂> is compared and the result is R₄ == R₂, then System.Array.Sort will indicate that R₁ == R₂, and does NOT compare < R₁, R₂> at all! Clearly, you could see that R₁ is Parent of R₂, < R₁, R₂> should be explicitly compared and the result should be R₁ < R₂.

The Idea of the Solution

So, how to sort the array so that no foreign-key constraints are violated? The idea is to treat the array as a forest, group all rows that have the same root into a tree, and compare the rows based on their root and their distance to the root. For example, suppose we have an array < R₁, R₂, …, R₁₄>, and the Parent-Child relationships among its elements are shown like picture below.

We still use System.Array.Sort<T>(T, ICompare<T>) to sort the array. That means we do not have direct control over the sorting algorithm, and we do not know what row pairs to be compared or the sequence of these comparisons. However, we do could impact the sorting process by controlling the comparison result of row pairs. That’s why we need to re-write the SelfReferenceComparer.Compare method.

The pseudo code of the new Compare method is (suppose Parent First):

int Compare (DataRow row1, DataRow row2)

DataRow root1 = row1’s root;

int distance1 = row1’s distance to root1

DataRow root2 = row2’s root;

int distance2 = row2’s distance to root2;

if (root1 == root2)

return distance1 – distance2;

else

return root1.RowIndex – root2.RowIndex;

end

How to Work-Around The Problem with Visual Studio 2008 SP1

With Visual Studio 2008 SP1, as a workaround, you could derive from the generated TableAdpaterManager and override its SortSelfReferenceRows method to implement this algorithm by yourself. Of course, you could put your code anywhere of your project, but it’s recommended to put them in the typed-dataset’s source code file. Right-click the typed-dataset (say, DataSet1.xsd), and choose “View Code”, Visual Studio will automatically create the source code file for you (DataSet1.cs in this case). It’s recommended you put your implementation code here.

Your code could be like this:

[C#]

// Derive from the generated TableAdapterManager and use it in your code instead

public class MyTableAdpaterManager : DataSet1TableAdapters.TableAdapterManager {

// Override this virtual method, and pass your own IComparer class

protected override void SortSelfReferenceRows(System.Data.DataRow[] rows, System.Data.DataRelation relation, bool childFirst) {

System.Array.Sort<System.Data.DataRow>(rows, new MySelfReferenceComparer(relation, childFirst));

}

private class MySelfReferenceComparer : object, global::System.Collections.Generic.IComparer<global::System.Data.DataRow> {

private global::System.Data.DataRelation _relation;

private int _childFirst;

internal MySelfReferenceComparer(global::System.Data.DataRelation relation, bool childFirst) {

this._relation = relation;

if (childFirst) {

this._childFirst = -1;

}

else {

this._childFirst = 1;

}

// Get the root of a row, and calculate its distance to the root

private global::System.Data.DataRow GetRoot(global::System.Data.DataRow row, out int distance) {

global::System.Diagnostics.Debug.Assert((row != null));

global::System.Data.DataRow root = row;

distance = 0;

// Save all traversed rows to avoid infinite loop

global::System.Collections.Generic.IDictionary<global::System.Data.DataRow, global::System.Data.DataRow> traversedRows = new global::System.Collections.Generic.Dictionary<global::System.Data.DataRow, global::System.Data.DataRow>();

traversedRows[row] = row;

global::System.Data.DataRow parent = row.GetParentRow(this._relation, global::System.Data.DataRowVersion.Default);

while ((parent != null) && !traversedRows.ContainsKey(parent)) {

distance++;

root = parent;

traversedRows[parent] = parent;

parent = parent.GetParentRow(this._relation, global::System.Data.DataRowVersion.Default);

}

// This is mainly for Deleted rows

if (distance == 0) {

traversedRows.Clear();

traversedRows[row] = row;

parent = row.GetParentRow(this._relation, global::System.Data.DataRowVersion.Original);

while ((parent != null) && !traversedRows.ContainsKey(parent)) {

distance++;

root = parent;

traversedRows[parent] = parent;

parent = parent.GetParentRow(this._relation, global::System.Data.DataRowVersion.Original);

}

return root;

}

public int Compare(global::System.Data.DataRow row1, global::System.Data.DataRow row2) {

if (object.ReferenceEquals(row1, row2)) {

return 0;

}

if ((row1 == null)) {

return -1;

}

if ((row2 == null)) {

return 1;

}

// Get root of row1 and calculate its distance to the root

int distance1 = 0;

global::System.Data.DataRow root1 = this.GetRoot(row1, out distance1);

// Get root of row2 and calculate its distance to the root

int distance2 = 0;

global::System.Data.DataRow root2 = this.GetRoot(row2, out distance2);

if (object.ReferenceEquals(root1, root2)) {

return this._childFirst * distance1.CompareTo(distance2);

}

else {

// Compare root1 and root2 with their row index to ensure the correct sort order

global::System.Diagnostics.Debug.Assert((root1.Table != null) && (root2.Table != null));

if (root1.Table.Rows.IndexOf(root1) < root2.Table.Rows.IndexOf(root2)) {

return -1;

}

else {

return 1;

}

[VB]

' Derive from the generated TableAdapterManager and use it in your code instead

Public Class MyTableAdapterManager

Inherits DataSet1TableAdapters.TableAdapterManager

' Override this virtual method, and pass your own IComparer class

Protected Overrides Sub SortSelfReferenceRows(ByVal rows() As System.Data.DataRow, ByVal relation As System.Data.DataRelation, ByVal childFirst As Boolean)

Global.System.Array.Sort(Of Global.System.Data.DataRow)(rows, New MySelfReferenceComparer(relation, childFirst))

End Sub

Private Class MySelfReferenceComparer

Inherits Object

Implements Global.System.Collections.Generic.IComparer(Of Global.System.Data.DataRow)

Private _relation As Global.System.Data.DataRelation

Private _childFirst As Integer

Friend Sub New(ByVal relation As Global.System.Data.DataRelation, ByVal childFirst As Boolean)

Me._relation = relation

If childFirst Then

Me._childFirst = -1

Else

Me._childFirst = 1

End If

End Sub

' Get root of a row, and calculate its distance to the root

Private Function GetRoot(ByVal row As Global.System.Data.DataRow, ByRef distance As Integer) As Global.System.Data.DataRow

Global.System.Diagnostics.Debug.Assert((Not (row) Is Nothing))

Dim root As Global.System.Data.DataRow = row

distance = 0

' Save all traversed rows to avoid infinite loop

Dim traversedRows As Global.System.Collections.Generic.IDictionary(Of Global.System.Data.DataRow, Global.System.Data.DataRow) = New Global.System.Collections.Generic.Dictionary(Of Global.System.Data.DataRow, Global.System.Data.DataRow)()

traversedRows(row) = row

Dim parent As Global.System.Data.DataRow = row.GetParentRow(Me._relation, Global.System.Data.DataRowVersion.[Default])

Do While ((Not (parent Is Nothing)) _

AndAlso (traversedRows.ContainsKey(parent) = False))

distance = distance + 1

root = parent

traversedRows(parent) = parent

parent = parent.GetParentRow(Me._relation, Global.System.Data.DataRowVersion.Default)

Loop

' This is mainly for Deleted rows

If (distance = 0) Then

parent = row.GetParentRow(Me._relation, Global.System.Data.DataRowVersion.Original)

Do While ((Not (parent Is Nothing)) _

AndAlso (traversedRows.ContainsKey(parent) = False))

distance = distance + 1

root = parent

traversedRows(parent) = parent

parent = parent.GetParentRow(Me._relation, Global.System.Data.DataRowVersion.Original)

Loop

End If

Return root

End Function

Public Function Compare(ByVal row1 As Global.System.Data.DataRow, ByVal row2 As Global.System.Data.DataRow) As Integer Implements Global.System.Collections.Generic.IComparer(Of Global.System.Data.DataRow).Compare

If Object.ReferenceEquals(row1, row2) Then

Return 0

End If

If (row1 Is Nothing) Then

Return -1

End If

If (row2 Is Nothing) Then

Return 1

End If

'Get root of row1 and calculate its distance to root

Dim distance1 As Integer = 0

Dim root1 As Global.System.Data.DataRow = Me.GetRoot(row1, distance1)

'Get root of row2 and calculate its distance to root

Dim distance2 As Integer = 0

Dim root2 As Global.System.Data.DataRow = Me.GetRoot(row2, distance2)

If Object.ReferenceEquals(root1, root2) Then

Return Me._childFirst * distance1.CompareTo(distance2)

Else

' Compare root1 and root2 with their row index to ensure the correct sort order

Global.System.Diagnostics.Debug.Assert((Not root1.Table Is Nothing) AndAlso (Not root2.Table Is Nothing))

If (root1.Table.Rows.IndexOf(root1) < root2.Table.Rows.IndexOf(root2)) Then

Return -1

Else

Return 1

End If

End Function

End Class

For the complete sample code, you could download it at Code Gallery. Cheers!

Some error messages when you use the Data Source Configuration Wizard in Microsoft Visual Studio 2008 Service Pack 1

Shichao Hu — Fri, 21 Aug 2009 16:27:41 GMT

After you install Microsoft Visual Studio 2008 Service Pack 1, in some situations, when you try to use Data Source Configuration Wizard to create a connection, you may see the following error messages,

Error message 1:

Could not load type 'Microsoft.VisualStudio.DataDesign.SyncDesigner.SyncFacade.SyncManager' from assembly Microsoft.VisualStudio.DataDesign.SyncDesigner.DslPackage, Version = 9.0.0.0, Culture=neutral, PublicKey Token=b03f5f7f11d50a3a

Error message 2:

The type initializer for 'Microsoft.VisusalStudio.DataDesign.SyncDesigner.SyncFacade.SyncTableConfigManager' threw an exception

These are due to an incomplete installation of Service Pack 1 or an incorrect installation of Microsoft Synchronization Services for ADO.net.

We have written a KB article (KB2001115) to explain the details and provide the solutions. Please see here if you met these issues,

http://support.microsoft.com/default.aspx/kb/2001115

If you need any further help, let us know.

DataRepeater Control for Windows Forms

John Chen — Wed, 12 Aug 2009 23:44:00 GMT

The DataRepeater control is available in the Visual Basic Power Packs.

As Yun Feng introduced in his post, the Visual Basic Power Packs is included in Visual Studio 2008 Service Pack 1 and will also be shipped in Visual Studio 2010.

The DataRepeater control is my favorite component in the Visual Basic Power Packs, which I proudly participated in from start to finish. Recently I monitored the Visual Basic Power Packs forum and I found that customers are saying nice things about the DataRepeater control as well. A lot of good questions have been asked in the forum. For example, how to print all the data in the DataRepeater, how to display unbound data, how to host a data bound ComboBox in the DataRepeater, etc… I feel motivated to write some posts to answer these non-obvious questions.

In this post, I will first present the unique features of the DataRepeater control from my perspective. Then I will show a simple walk through for using a DataRepeater control in a data binding application. At the end, I will list the resources available for reference.

First of all, I would like to point out that the DataRepeater control is a true .Net Windows Forms control. It can be used not only by Visual Basic but also for any other .Net language (e.g. C#). You may be curious why it is under the Visual Basic Power Packs “brand”. The project was initially designed to help VB6 customers migrating to the .Net world with familiar experience and environment. We started the project with the Visual Basic customers in mind as there was already a Data Repeater Control in Visual Basic 6 and unfortunately there was no corresponding control in Visual Studio.Net 2002 to 2008. After we created the control we realized that it would be good for all .NET customers and we decided to make it available to all of Visual Studio.

To differentiate the DataRepeater controls in VB6 and the one now in Visual Studio 2008 SP1, in this article I would call them VB6 DataRepeater and PowerPacks DataRepeater (or simply DataRepeater). The PowerPacks DataRepeater inherits the basic concept of the VB6 DataRepeater control to display repeated data in a scrollable container. Even more, the PowerPacks DataRepeater has significant improvements over the VB6 DataRepeater. The PowerPacks DataRepeater is modern (as I said, it is a .Net control can be used by all languages), more powerful, has more functions, and yet easier to use taking all the advantages of the .Net and Visual Studio Data Access tools and technologies.

For example, in VB6, you need to create an intermediate user control to host the VB6 DataRepeater and set up the data binding there, build it and then include the user control in the host form. With PowerPacks DataRepeater, the intermediate user control is no longer needed! You can now drag and drop the DataRepeater control onto the hosting form directly, and then drag and drop controls on its item template section. You will enjoy a truly WYSIWYG design experience.

Although both DataRepeater controls can host free style controls in the item template section, the PowerPacks DataRepeater allows you to have even more controls on the layout and the appearance of the repeating items. You can use the DrawItem event to customize the color or other appearances as you wish. The LayoutStyle property lets you specify orientation (vertical or horizontal) of the displayed items. The orientation feature is really attractive and I have seen some customers choose the DataRepeater over the DataGridView simply because the DataRepeter can show data in horizontal orientation.

Talking about the DataGridView, the PowerPacks DataRepeater control can be seen as an alternative control to the DataGridView. The PowerPacks DataRepeater follows the design of the DataGridView and you can find many properties (e.g. the Virtual Mode property) in DataRepeater control in parity with the DataGridView. This description from MSDN document best describes the role of the PowerPacks DataRepeater -- “It can be used as an alternative to the DataGridView control when you need more control over the layout of the data.”

The PowerPacks DataRepeater control applies a virtualization technique to display the data in a fashion that scrolling and navigation is fast while rich UI and visual effects are still retained. For example, all displayed controls on the display surface are real controls and you can interact with them without delay. Scrolling is smoothly simulated while VB6 DataRepeater does not have a scroll effect.

You can further improve performance by turning on the Virtual Mode when you want to display large quantities of tabular data in a PowerPacks DataRepeater control. The Virtual Mode allows you explicitly manage the control’s interaction with its data source. Therefore you can load the data rows only when necessary to reduce the initial loading time. You can also reduce the memory consumption by only loading part of the rows into memory at any given time. Notice that if you already have all data rows loaded into memory like a DataSet filled by the TableAdapter.Fill method, you will not have the performance gain with Virtual Mode.

To demonstrate the ease of use of the PowerPacks DataRepeater control, let me give you a walkthrough for building an application with the DataRepeater control.

First I would create a C# Windows Forms Application in Visual Studio 2008 SP1 or 2010 (yes, I purposely choose a C# project here to show that it is not only for VB, the steps in this demo have no difference between C# and VB).

And then I want to create a DataSet data source with the DataSource Configuration Wizard or DataSet Designer. I will assume you are familiar with this part and a DataSet with Employees table connecting to the sample Northwind database is ready to use. You will see that the Data Sources Window on the left hand side is populated with the Employees Datatable (see Picture 1 bellow).

Picture 1 – DataSet designer and Data Sources window.

Now, let’s open the Form and show the Toolbox. You can find the Power Packs tab (see picture 2, marker 1, shortened as Pic.2-1), expand it and you will find the DataRepeater toolbox item (Pic.2-2). Drag and drop the DataRepeater toolbox item to the form (Pic. 2-3), you will see two sections in the location of the DataRepeater1 control on the form. The outer section (Pic.2-4) is the total display area of the control and the inner section (Pic.2-5, a.k.s. the Item Template section) holds the repeating items. It also defines the size of the repeating items and the location of the first item. You can fine tune the look and feel of the outer and inner section of the DataRepeater control as you wish.

Picture 2. Drag and Drop DataRepeater to the Form

I select my DataRepeater by clicking on the outer section of the DataRepeater, the Property Brower should show as in Pic. 3-1. And I set the anchor as top-left-right (Pic.3-2) and the LayoutStyle as Horizontal (Pic. 3-3).

Picture 3. DataRepeater layout

Now, let’s fill the DataRepeater item template section with some data bound controls. I show the Data Sources Window (Pic. 4-1), change the employees table’s view to detail (Pic. 4-2), change the First and Last Name to label (Pic. 4-3), leave the Title as default TextBox (Pic. 4-4), and change the Photo to a PictureBox (Pic. 4-5). I then drag and drop these items to the DataRepeater item template section as indicated in the picture and remove the unnecessary extra labels. Note that it will also cause the auto creation of the navigator bar (Pic. 4-6), Dataset, BindingSource, TableAdapter, etc.(Pic. 4-7). The experience is exactly the same as when you drag and drop detail view items from the Data Sources window to a form or any container control. The difference is now the data bound items in the Item Template section will now be repeated at run time.

Picture 4. Drag and drop detail view items from Data Sources window to the item template section

Now I am happy with the setup and eager to see what is out there, I hit F5 to test my app, and I got this result, that is all I need. You can scroll the data by clicking on the scroll bar or the forward and backward button on the navigation bar. You can select an item, and modify the value on any editable control on the item like Title text box (Pic. 5-1). You can add new item (Pic. 5-2), delete an item (Pic. 5-3). And you can save all the changes (Add/Delete/Update) with the save button (Pic. 5-4).

Picture 5. Run time result

To summarize, creating a data binding application can be simply done with these 3 steps: 1) Create the data source; 2) Drag and drop a DataRepeater control to the form and adjust its look and feel; 3) Drag and drop detail view items from Data Sources Window to the item template section of the DataRepeater control.

Lastly, let me wrap up with some more information:

The sample projects (VB and C# 2008 SP1 version) in this post can be found in MSDN Code Gallery Power Packs Samples
For a detail instruction of a similar walk through, see MSDN article: How to: Display Bound Data in a DataRepeater Control (Visual Studio)
For a related video demonstration, see How Do I: Use the DataRepeater Control? presented by Beth Massi.
For MSDN DataRepeater introduction article: See Introduction to the DataRepeater Control (Visual Studio)
For DataRepeater class reference: See DataRepeater Class
For questions and feedback: See Visual Basic Power Packs forum
For VB6 reference, see Data Repeater Control in Visual Basic 6
For accessing data technologies in Visual Studio: See VS2010 Beta1 version or VS2008 version

As mentioned above, my colleagues and I will post more articles to answer some advanced or non-obvious How-Tos in the near future. Stay tuned!

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Follow-up blogs:

8/27/09 Gavin Fu: How to Change Appearance of all DataRepeater Items at Run Time
9/8/09 John Chen Writing Event Handler for controls in a DataRepeaterItem

My experience on Connect Feedbacks

John Chen — Tue, 09 Jun 2009 19:02:00 GMT

Recently I have been working with some Visual Studio feedbacks reported through Microsoft Connect. I found that some feedbacks may contain multiple unrelated issues. On the other hand, one issue may be reported several times by the same person in different feedbacks. There are also issues about crashing, memory, performance, debugging, etc. I will share some tips here that I think can benefit both Microsoft and our customers.

1. Report only one issue in one feedback. As you may know that there are many teams working for Visual Studio and Dot Net framework. Different issues are more likely handled by different teams, product units or even divisions. Multiple issues in one feedback will be hard to track and individual issues may not be routed to the right team promptly.

2. Do come back to check the feedback often. We may often ask for detail repro information in order to reproduce the issue. If the issue has been resolved as not repro but you have more info, don’t worry or get angry, just reactivate the issue and adding the new information. Some customers tend to open new feedbacks in this case. I think stick to the old issue and continue the communication would be a better approach. Of course, if the time span is too long, a new issue is appropriate.

3. When a crashing occurs and you see the dialog asking you to send the feedback, click the send button. This will send the important crashing information (like call stack) to Microsoft and the information will be analyzed.

4. If you have issues regarding crashes, hangs, slowness, or out of memory errors, you can collect the information with the performance diagnostic tool available here (you need to log in as a connect user first).

5. If you want to use the VS debugger to get a call stack or dump file of an exception of VS, you can do so with a second instance of Visual Studio, see the post I have here .

Hope this helps.

How to get call stack of Visual Studio?

John Chen — Tue, 09 Jun 2009 02:45:16 GMT

If you want to use the VS debugger to get a call stack or dump file of an exception of VS. You can do so with a second instance of Visual Studio. Here is the steps I would use:

1) Have your working Visual Studio running: let’s call this Visual Studio as VS1.

Proceed to the point right before the exception is about to happen.

2) Open a second instance of Visual Studio (make sure this is the only second instance): let’s call it VS2.

3) Setup VS2 debug option as following

a. Open Tools Option menu

b. Drill down to Debugging\General, find out the Enable Just My Code (Managed Only) item, and uncheck it.

c. Drill down to Debugging\Symbols, Set your symbol path to http://msdl.microsoft.com/download/symbols and cache the symbols to local directory like c:\symbols

d. Click OK to close down the dialog (note the debugger may take long time to down load the symbols for the first time, once the symbols are cached, it will be faster next time).

4) In VS2, attach the process of VS1

a) Open Debug\Attach to process… menu command

b) In the Attach to Process dialog, Set Attach to parameter by click the Select button (see the picture bellow)

· Set to Managed code only if you want to debug only managed code (it will be faster to choose the small set of debugging type)

· Set to Native code only if you want to debug only native code.

· Set both or automatic if not sure.

If you need to save the dump file, you need to include the native code.

c) Then double click on the devenv.exe from Available process

Devenv.exe is the visual studio instance.

5) Enable break on exception

a) In VS2, open Debug\Exceptions menu and check on Common Language Runtime Exceptions for managed code. Add other checks if necessary.

b) Clock OK to close the dialog.

6) Now go back to VS1, use the VS to allow the exception occur.

7) You should see the exception captured by VS2.

8) In VS2, open Debug\Windows\Locals to see the current exception

a) Make sure the exception is the right one, hit F5 to continue to the next exception if necessary

9) In VS2, open Debug\Windows\Call Stack to get the call stack window.

a) Copy the full stack and send back to your Microsoft representative.

10) Get dump file.

If you include the native code debugging, you can use Debug\Save dump file as menu to save dump file. Send the dump file to Microsoft representative.

I am using Visual Studio 2008 as the example above. Other versions should have similar steps.

Also notice that if you have issues regarding crash, hang, slowness, out of memory error, you can collect the information with the performance diagnostic tool available here.

Building WPF Business Applications using Entity Framework

Beth Massi — Sat, 16 May 2009 05:06:57 GMT

I’ve been writing a lot about building WPF business applications with Entity Framework using Visual Studio 2008. If you’re just starting this type of development you may want to read the following:

I also highly recommend Julie Lerman's Programming Entity Framework book.

I’ll be adding more articles and How Do I videos so you may want to keep tabs on me and the EF team blog. :-)

Enjoy,
-Beth Massi, Visual Studio Community

Using TableAdapters to Insert Related Data into an MS Access Database

Beth Massi — Fri, 15 May 2009 04:54:00 GMT

I’ve posted before about how to use TableAdapters to update parent-child (master-detail) relationships against SQL server. It’s pretty straightforward and Visual Studio generates all the code for you to properly insert, update and delete your data. However if you’re using MS Access then there’s one thing that Visual Studio doesn’t do because it’s not supported when using Access.

Read more on my blog here…

VS 2005 patch for SQL Server 2008

MilindLele — Wed, 21 Nov 2007 23:14:00 GMT

SQL Server 2008, Noverber 2007 CTP was recently released.

We've also released a CTP of Visual Studio 2005 Support for SQL Server 2008. This will enable you to use VS2005 against SQL Server 2008. For more information about this patch, see the Knowledge Base Article 942246.

New Data Tools Features in Visual Studio Orcas

youngjoo — Fri, 09 Mar 2007 13:51:00 GMT

Here's a list of new data tools features in Visual Studio. I will be discussing each one in more detail in upcoming posts.

Object Relational Designer

The object relational mapping technology lets you map relational databases to objects. Once the mapping is done, you can manipulate mapped objects as normal objects and easily submit changes back to relational database without writing complex data access logic. It is the latest enhancement in data access technology and there are many different implementations out there currently. However, no O/R implementation comes with a graphical designer that makes it easy to create and modify mapping.

The Object Relational Designer in Visual Studio is Microsoft's answer to how O/R mapping should be done. It's a graphical designer which lets you easily map database objects such as tables and stored procedures to LINQ To SQL classes and methods. You can just drag out database objects from the Database Explorer onto the designer. Designer then takes care of creating mapping and generating proper LINQ To SQL code. You can also modify different aspects of mapping through the designer and let the designer take care of updating the code automatically. Association and inheritance relationships can also be easily created easily. The stored procedure support is also a very unique feature. Instead of letting LINQ To SQL generate INSERT, UPDATE and DELETE SQL statements, you can map methods created based on the stored procedures to each behavior.

If you've tried May CTP of LINQ, you probably remember a version of the O/R Designer we included. It was called DLinq Designer. What you see in March CTP of Visual Studio Orcas is the next generation of DLinq Designer and it's now called the O/R Designer.

Hierarchical Update in Typed Dataset

Keeping track of all inserts, updates and deletes across multiple related datatables and sending those changes in the right order back to the server is not an easy task. How do you make sure that new orders for your customer are added correctly to the system while updating the shipping address of the same customer and deleting one of old orders that had been cancelled all at the same time?

With hierarchical update support in Typed Dataset, all you need to do is to call UpdateAll() method of the new TableAdapterManager component we've added. It takes care of collecting all changes and sending them back to the server in the right order. Of course, everything is wrapped into a transaction.

We believe this would significantly improve the productivity of developers using Typed Dataset to create data applications. You can try this new feature in March CTP of Visual Studio Orcas.

N –Tier Support in Typed Dataset

I admit. Typed Dataset code we generate in Visual Studio 2005 is not N-Tier ready. If you open up the code file, you will notice that we've done a great job separating types from data access logic. Dataset and typed datatables are declared in one Typed Dataset class and all TableAdapter classes are declared under a separate namespace. But we generate both sets in one code file. For a lot of applications this is not an issue. But when you are building multi-tiered applications, having them in one file doesn't really help. This exact problem is discussed in detail on Splitting Typed Datasets from TableAdapters blog entry from Steve Lasker. The solution proposed in this blog entry was to open up the generated code and manually copy and paste type declaration out into a new class file. Although this did allow you to use Typed Dataset in N-Tier scenario, it had one major problem. Since you are manually modifying generated code, anytime you make a change to Typed Dataset via Dataset Designer, you have to remember to copy and paste code. That was painful.

In Orcas, you can instruct the designer to generate Dataset portion of the code into another project in your solution. No more manual copy/paste. You can even make changes to Typed Dataset from the designer and it will make sure that updated code is generated into the specified project. You can still choose to stay in 2-Tier model. Designer will continue to generate everything in a single file. When you are ready to take your 2-Tier application to N-Tier, just tell the designer which project is the Dataset project and you are done. It's that simple. A preview of this feature is in March CTP of Visual Studio Orcas and you will be able to try the polished version in Beta 1.

Local Data Cache with SQL Compact Edition

SQL Compact Edition enables many exciting scenarios for developers. The most interesting scenario is to use SQL Compact Edition database file as a local cache of data that do not change often. For instance, your application might keep a list of products in local cache while exchanging order information with remote server. Once in a while, you can synch products list from the remote server but you will mostly use local cache.

Since SQL CE is light-weight database that has very little overhead, it's the perfect candidate for the local cache store. You can use the Sync Service for ADO.NET to synchronize data between remote database server and local SQL CE database file. Sounds great, right? But how do you set everything up so that you can do this?

Visual Studio Orcas includes new project item template "Local Data Cache". Adding "Local Data Cache" to your project creates .sync file which is an XML file that describes what gets synched and how. This file comes with the designer that lets you configure different aspects of synchronization easily. Designer also creates SQL CE .sdf database file to be used as local cache store as well as synchronization code necessary to interact with the Sync Service. A preview of this feature is in March CTP of Visual Studio Orcas and you will be able to try the polished version in Beta 1.

Other Enhancements to Data Tools

Above four are major data tools features in Visual Studio Orcas. But there are tons of other enhancements we've made to existing data tools. I will be dedicating a separate post to describe other important enhancements we've made.

- Young Joo, Program Manager, Visual Basic