What Is The Data Context Property
Aug 12, 2010
I was reading the MSDN manual, I was reading about the about the binding.source property. I got a little confused because the manual started taling about the data context property. My question is what is the data context property ? Whenever I look through the properties of an object ( either textbox, datagrid etc ) I can't see this property listed anywhere.Could it be that the version of visual basic that I'm using ( which is Vb 2008 express ) doesn't include this property.
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Apr 13, 2010
I have an app that allows the user to choose an image, at design time, either as a straight image, or from an image list.
All cool so far, except that this is not happening from the visual studio property browser, its happening from a property grid that is a part of a type editor.
My problem is, both the image picker (actually resource picker), and the imagelist type converter rely on some design-time services to get the job done. In the case of imagelist, its the IReferenceService and in the case of the resource picker its a service called _DTE.
In the first instance of an edit from the visual studio property browser, I could get a reference to these services but (1) how can I add them to the type descriptor context of my property grid?
It would be better, for future proofing, if I could just copy a reference to all of the services in the type descriptor context. (2) Where does the property browser get these services from in the first place?
ETA: I still don't know how to do it, but I now know it is possible.
(1) Sub-class control and add a property whose type is an array of buttons.
(2) Add it to a form.
(3) Select the new control on the design service and edit the new property in the property browser.
(4) The collection editor dialog pops-up
(5) Add a button
(6) Edit image and image list - the type editor and type converter, respectively, behave as they should.
ETA2: Ok, I'm getting warm. It looks like you do it through the Site property of the property grid. I can create a new site, and pass it the type descriptor context I have a reference to and then it should have all the service. I'll give it a go ...
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Apr 12, 2010
I am having a Friend Class InterceptingChannelBase class.It has a property as below:
Protected ReadOnly Property InnerChannel() As TChannel
Get
Return Me.innerChannelT
[code]....
This class is being inherited by (Friend Class InterceptingInputChannel) class which in turn contains another (Private Class TryReceiveAsyncResult) class.The property above is being used in this private class as below:
Public Sub New(ByVal channel As InterceptingInputChannel(Of TInputChannel), ByVal timeout As TimeSpan, ByVal callback As AsyncCallback, ByVal state As Object)
MyBase.New(channel, callback, state)
[code]....
I am getting the error on the above underlined statement saying that Protected Readonly Property InnerChannel is not accessible in this context because it is declared asa Protected.As far as i think,if i declare a property in class as 'Protected' then if this class is inherited by 'another' class then i can use this property and it should not throw an error.
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Aug 20, 2009
When bulk renaming files (14000 of them) i get this error: The CLR has been unable to transition from COM context 0x4cefd8 to COM context 0x4cf148 for 60 seconds. The thread that owns the destination context/apartment is most likely either doing a non pumping wait or processing a very long running operation without pumping Windows messages. This situation generally has a negative performance impact and may even lead to the application becoming non responsive or memory usage accumulating continually over time. To avoid this problem, all single threaded apartment (STA) threads should use pumping wait primitives (such as CoWaitForMultipleHandles) and routinely pump messages during long running operations.
My code is as follows:
Private Sub frmTest_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Dim asd As List(Of String) = FileIO.FileSystem.GetFiles("D:Music").ToList
Dim rs As New ADODB.RecordSet("SELECT * FROM Songs", My.Settings.Files_Database__Connection)
[code].....
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Apr 15, 2009
I'm using a context menu strip that gets its data items from code that grabs filenames of .BAT files in a pre configuired directory. I need to execute code depending on which toolstrip menu item is clicked, i kno how to do this is the items are hard coded but not when they are dynamically added at runtime
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Oct 25, 2011
I'm working with system using Linq-2-SQL as its data layer, but which uses stored procedures to do the actual CRUD operations - the stored procs are configured against the CRUD methods for the data class in the model designer.These are all working just fine.Now we want to use partial classes to extend the functionality of our data classes to apply validation, and hold parsed versions of some of the database properties.
However when I create a partial class for one of the data classes, the datacontext stops using the methods configured against the dataclass and defaults to its own operations. This happens even if the partial is empty other than the just the class declaration.
I would guess that this might be because the method signature for the insert method stops tying up to what the datacontext is looking for, but I can't see any overrides available to help fix it.Is there a way around this so that I can use Partials and Stored Procs on the same data context?
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Aug 8, 2009
[code...]
In particular the MetadataProviderFactory Line... I can't quite seem to figure out how it should look in VB.
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Jul 2, 2009
I have a context menu strip (named cmnuRtxtIT) that pops up by right clicking on top of a rich text box in a VB 2008 WinForms application. Context menu strip cmnuRtxtIT has one item named ToolStripMenuInsertFld. This last one has one dropdown item named oolStripComboBoxFlds which is a ToolStripComboBox type. I do the following in the form's Load event to bind ToolStripComboBoxFldsto an Sql database:
Dim dt As New DataTable
Dim dta As New SqlDataAdapter("SELECT pkID, txtFlds FROM ApplicationFields", goConn)
dta.Fill(dt)
[code].....
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Feb 25, 2011
I'm currently trying to create a NEWID() function in my DataContext in LINQ using the solution here, however, when adding the partial class to my DataContext.vb or a separate DataContextPartial.vb, I get the error System.Data.Function is not available in this context because it is 'Friend'.
I've come across this when accessing data types before and that was in easy fix of setting it to Public, but I'm not sure where the properties for function could be or how to change them.The code I have is converted to VB.NET from the C# in the linked answer above:
Partial Public Class CMSModelDataContext
<[Function](Name:="NEWID", IsComposable:=True)> _
Public Function Random() As Guid
[code]....
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Oct 10, 2011
I've done this many time before, but for some reason I can't get it to work this time.I'm trying to get a ContextMenuStrip associated with a DataGridView. I've defined each to the form and in the properties of the DataGridView I've set the ContextMenuStrip property equal to my ContextMenuStrip name (cmsDictionary), defined the onClick event code, but when I run nothing happens.
The program was originally code with a dynamically added context menu but it was popping up all over the place and I wanted to remove that and just let the grid manage it.
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Jul 27, 2009
If I'm extending OnCreated for a LINQ to SQL table object, is it possible to get a reference to the data context to which the table belongs? For example, if I add a property to the data context:
Partial Class MyDataContext
Private _myValue As String
Public ReadOnly Property MyValue As String
[Code].....
I don't want the property on the data context to be Shared, because it could be different per instance. I've been pouring over the designer code to figure out where the reference might be, but no luck yet.
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Jun 8, 2011
I got this message because of a long process: ContextSwitchDeadlock was detected
Message: The CLR has been unable to transition from COM context 0x3dc190 to COM context 0x3dc300 for 60 seconds. The thread that owns the destination context/apartment is most likely either doing a non pumping wait or processing a very long running operation without pumping Windows messages. This situation generally has a negative performance impact and may even lead to the application becoming non responsive or memory usage accumulating continually over time.
To avoid this problem, all single threaded apartment (STA) threads should use pumping wait primitives (such as CoWaitForMultipleHandles) and routinely pump messages during long running operations. I've poked around on the internet and on a forum, someone suggested to use application.doevents(). I did that and the messaged goes away. In an earlier thread a member wrote that using application.doevents rarely was used appropriately. Is my situation a proper usage of application.doevents or is there something else I should be doing?
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Feb 22, 2011
Modifying data with the ListView's EditItemTemplate by programmatically settings its DataSource property and calling its DataBind method. I don't have option to use data source control for ListView. All ListViews are bound with data from code-behind. So, I have to handle the Edit/Update mode of ListView manually. [Code]
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May 15, 2010
VB express 2008 .net 3.5 or .net 4.0 VB express 2010?I have written application to convert RTF to HTML. The main Purpose of the application is to copy VS code to the clipboard and covert it then put it back into the clipboard as a HTML Document so that it can be pasted into a HTML document such as Windows Live Mail. I found that code copied and pasted is spaced out in in the wrong positions.
The applications works perfect with no bugs so far. I then asked Myself how to go about doing the copy with the least amount of operator interaction. So I added an Icon to the Icon Tray with a right click menu to use to convert once the Rich Text Format was copied to the clipboard. This works fine except you have Five steps, Select the text, Copy to clipboard, Right Click the icon, Select the Converter and Paste. The normal is three steps.
To this the best solution is to add a context menu item to the active form such as the RTF editor or window. So that when you select the Rich Text to copy and right click on the form to bring up that menu then to Just Select the menu Item such as "Copy RT and Convert" I searched and found about 544000 Items and tried to restrict down to no avail. I read until I finally gave up. I did not find any code examples of this. Almost every thing I found related to the web or some other explicit document like Excel and not to the Various windows that could be active with RT in it.
how do you add a context menu item to the context menu of an active rich text format window such as WordPad or VB?I have test in my application that tests to see if it is a RTF in the clipboard so if it is not the converter does nothing.
Imports System.Threading
Imports System.IO
Imports System
[code]....
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Feb 1, 2011
I am getting an error message: "Pervasive.data.sqlclient.v is not accessible in this context because it is 'friend.'" This error message appears when I hover the cursor over the "For Each v In qv" line in the following code:
[Code]...
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Dec 9, 2011
I'm having some very weird issues with interfaces right now.
I have a very simple setup. In one of my class, I have a Property implementing a Property from an Interface.
In my class it's like:
Private _oForm As IForm
Public Property Form As IForm Implements IContainer.Form
Set(value As IForm)
[Code]...
I have like dozens of interfaces like this working throughout my project and I can't believe this simple one can't work!
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Jul 30, 2011
Looking at this table describing the data types in VB.One of the columns is labeled "Nominal storage allocation". What does this mean? Why is the word "nominal" here?
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Apr 4, 2011
I have a project in WPF 4 and VB.net 2010. I want to bind the volume property of a mediaelement to a variable in another module. Mind you, the variable is in the correct data type, so no conversion is necessary
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Dec 16, 2011
I have a "generic" Tag class which holds an ItemValue, which at this time is declared as Object. The ItemValue could be one of several datatypes; String, Boolean, Integer, etc. Is there a way to create a class property to identify which data type the Tag is?
I've tried this but it's not working;
Public Property DataType As Type
Get
Return m_DataType
[code]....
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Apr 12, 2011
Does anyone know of a control such as a Checked List Box where each item can have a value against it.For example you have a list of fruits and in the listbox it displays Apple, Orange & Banana but the values for those items are A, O & B.
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Apr 14, 2010
In silverlight, can you bind to a property that contains parameter? For example, the following doesnt seem to work. Am I missing something or is this not possible?
C#
private System.Collections.Generic.Dictionary<string, string> ValuesField = new System.Collections.Generic.Dictionary<string, string>();
[code].....
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Feb 17, 2010
I am trying to build a dynamic validator for a data entry application. I want to be able to query a table for the validators relating to the current task and then be able to reference class properties based on the description of the validators returned.
ex. Validator = "person/firstname"
How do I get to _clsPerson.FirstName?
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Jun 2, 2011
[code]This is my Code the error is Class 'System.data.datatable' cannot be indexed because it has no default property.. When i try this code in oledb it works but here it wont..
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Nov 11, 2011
when i got to ADODC and try to go to connectionString in the properties of ADODC, the ConnectionString Dialog Box will not open when i click on it its wants me to type some kind of text. However on tutorial it clearly states that a dialog box should open up.
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Apr 15, 2011
I have an Entity Data Model with two entities in it "Roles" and "Users". There is a navigation property from I have a EntityDataSource and a GridView. The EntityDataSource points to the Users entity and has an Include="Roles" parameter.I've added a BoundField in the GridView that points to RoleName, a property of the entity Roles. However, when I execute the code I get the above error.I have used very similar code successfully in another application. Any ideas why this isn't working?
Here is my EntityDataSource:
<asp:EntityDataSource ID="EntityDataSource1" runat="server"
ConnectionString="name=pbu_checklistEntities"
DefaultContainerName="pbu_checklistEntities" EnableDelete="True"
EnableFlattening="False" EnableUpdate="True" EntitySetName="Users" Include="Role">
</asp:EntityDataSource>
And here is the BoundField:
<asp:BoundField DataField="RoleName" HeaderText="Role" SortExpression="RoleName" />
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Oct 3, 2011
I am using the code below to export records in a datatable to an excel file using EPPlus.
Dim excelPackage = New ExcelPackage
Dim excelWorksheet = excelPackage.Workbook.Worksheets.Add("DemoPage")
excelWorksheet.Cells("A1").LoadFromDataTable(dt, True)[code]....
However, after walking through the code block, at Response.End(), I get an exception {Property evaluation failed.}
Update:
The error log is:
ERROR: System.Threading.ThreadAbortException: Thread was being aborted.
at System.Threading.Thread.AbortInternal()
at System.Threading.Thread.Abort(Object stateInfo)
at System.Web.HttpResponse.End()
at Reporting.Page_Load(Object sender, EventArgs e) in C:Reporting.aspx.vb:line 38
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May 6, 2010
in a new project I thought I would try to integrate the new Entity Model Framework, but am having some issues/problems and would like to know if there is a solution or workaround that will let me insert a record into a table that has an identity property.At first I thougth it might simply recofnize the storedprocs that I have for insert/update/delte actions, and was a bit discapointed when generating the model ignored all my stored procs. So I thought wll heck maybe it just generates a nice insert method for me. Lets see.So I referenced my model and found that for the table (entity) there was an insert action (method) that had been generated, however what i found is that it explicitly added the primarly key field - which was based on an identity property and will not accept an explicit insert value.So I guess 2 questions
1. How do we work with identity properties
2. How can we take advantage of the performance and securtiy advantages that stored procs offer with SQL server?
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Feb 27, 2012
I have a Query that is in designe mode I have created 4 columns and formatting 4 columns also in datagrid view control now I want to use datasource of dgv control now when i defining datasource property with table then dgv control displaying my predefine columnas and adding 4 more columns in dgv for defining datasource.now presently to avoid autogenerating columns I definie the autogeneration column=false at this situation if i define datasource=table the no data is come up..so my query is it is possible to filled up data in predifned column using datasource property.
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Mar 28, 2011
I have a user control inside of a repeater that is being bound by a sqldatasource. I get the following error: Databinding methods such as Eval(), XPath(), and Bind() can only be used in the context of a databound control. EDIT: NEVERMIND Egg on my face. I was getting this databind error because I was binding it somewhere else in an effort to troubleshoot my real problem from last friday but I forgot about it.
WHAT MY REAL PROBLEM IS: The usercontrol is getting bound before the properties get set so it appears as if they are never set. When stepping through I see that they get on the property is hit before the set on the property is hit. For example if I put <%# EVal("Address_ID") %> before the user control I will see the ID displayed but then the user control will display an emptydatatemplate because it is being passed the ID of 0.
<asp:SqlDataSource ID="sqlFacilityAddresses" runat="server" DataSourceMode="DataSet" SelectCommandType="StoredProcedure" SelectCommand="SP_Facility_GetAddresses" ConnectionString="<%$ ConnectionStrings:Trustaff_ESig2 %>">
[code].....
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Nov 15, 2010
I am using VB 2008...
On my form I have a "Combobox1" that pulls a list from an access table. I also have a "DataGridView1" that pulls data from another access table.
I am trying to set the "DataSource" property of the "DataGridView1" after clicking a button, which pulls the "Text" property from the "ComboBox1".
ComboBox1.Text will always equal DataGridView1.DataSource as a text string.
I researched the Get/Set command, but it does not make sense to my specific application. I have read countless articles online for weeks, but I have now taken the next step.
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