VS 2008 Items Collection Cannot Be Modified When The DataSource Property Is Set
Feb 13, 2010
I have two tables "Person" and "Alias" in a one to many relationship. I have a DGV for "Person" and want to use a combobox for the Aliases. I also have a textbox and a button for the user to type the alias name and click the button to add the alias name to the combobox and update the dataset. I keep getting the "Items collection cannot be modified when the DataSource property is set." Error. But if i use a DGV instead of a combobox for aliases, I have no errors and everything works fine. If I remove the datasource property for the combobox it will not get populated with the data already entered, so how, or can I, set it up where the combobox gets populated when the form loads and able to add items to the combobox????
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Apr 27, 2010
I am trying to refresh my combobox when an item is selected and added the highlighted code as shown below; [code]Items collection cannot be modified when the DataSource property is set.
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Jun 17, 2010
I have a combobobox on my form, and I use the following code to populate the data from SQL Server:
cbname.DataSource = DSAssetName.Tables(0)
cbname.DisplayMember = "IDWLNAME"
cbname.ValueMember = "FIDWID"
[code].....
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Aug 26, 2011
Like i want it to read the lines i have in the text file but i get an error Each time i press the button Why?
Private Sub Button5_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button5.Click
Dim objreader As New System.IO.StreamReader("C:UsersJamesDesktopMusicas.txt")
Do Until objreader.EndOfStream
[code]....
Error:
Quote:
Items collection cannot be modified when the DataSource property is set.
Error line
Quote:
ListBox1.Items.Add(objreader)
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Sep 7, 2011
I have the following classes:
Product, Service and OrderItem
Product and Service must inherit OrderItem. So basically I want to store OrderItem object in my shopping cart and these object are store in a list.
Public MustInherit Class OrderItem
Private m_enuItemType As TypeOfItem = TypeOfItem.None
Private m_strUserID As Integer[code].....
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Jun 19, 2009
I have several custom classes in a VB.NET (VS2008) project which are related to each other through generic list collections. The lower tier classes refer directly to some of the parent classes (to make it easier to refer backwards up the chain). My question is, is it possible to add the reference to the parent class when the item is added to a collection, when that collection is a property?
Below is some sampling of code to illustrate.
Public Class FlexServer
Private m_FlexLicenses As List(Of FlexLicense)
Private m_Modules As List(Of FlexModule)
Public Property FlexLicenses() As List(Of FlexLicense)
[code] .....
In the code above I have the FlexServer class which refers has two lists as properties, one for FlexLicense and one for Modules. The FlexLicense class has a property to refer back to the FlexServer class that "owns" it. In order to update this property in code, I have to add the FlexLicense to the FlexServer.FlexLicenses list AND set the FlexLicense.FlexServer property. What I am looking for is, is there a way (in the property definition or wherever) to both add the item to the list and alter it at the same time?
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Dec 25, 2009
i import into a list box data from a db. when i try to save listbox it save this text
System.Data.DataRowView
instead text of single item...
how i can get the real text of each item?
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Apr 14, 2010
During Loading a form, I bind a datasource property of the DGV to the bindingsource, and then set the fillweight property of the DGV columns. But, after form being shown, earlier set properties are being reseted to default = 100.
The procedure is like:
1. TestForm.Show()
2. TestForm_Load(...) Hnadles MyBase.Load
DGV.DataSource = bindingsource
DGV.columns(0).fillweight = 80
DGV.columns(1).fillweight = 120
3. Me.close() (Closing the form which called TestForm.Show()
And now I have visible a TestForm with well binded datasouce seeing all the columns, but their fillweith property was beeing reseted...
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Dec 23, 2011
I get that error any time my form closes(Me.Close), even if I don't do anything to the form at all exept load another form like this: Form2.Show Me.Close().
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Nov 19, 2009
I need to create a user control which can be used in my all projects. I have created a user control with a TextBox Control and a ListBox Control. My goal is that as soon as any character is pressed in the textbox, Listbox's item which starts from that character should be selected. I have done all the coding needed for the functionality but my problem is that when I add this usercontrol to my form, I should be able to change the DataSource, displaymember and valuemember properties at designtime. But I cannot see these properties when I add the control on the form.
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Aug 4, 2011
We have some third party code that is causing some misery at the moment due to throwing the above error: it is slightly odd because it is an intermittent error. Here is the method that is causing the issue:
Private Shared Sub IntLocateDictionaries(ByVal haystack As ExpDictionary,
ByVal needlearray() As Object, _
ByVal resultarray() As Object, ByVal removemarks As Boolean)
Dim i As Integer
Dim item As Object
[Code] .....
I understand that this error is usually caused by trying to modify a collection whilst enumerating around it, hence why I've added logging on the only line that looks like might alter the collection... Since adding the logging we have still experienced the issue but NO LOGGING appears: this isn't surprising since if you look at the parameters on the calling line (the only place this Sub is called from) - removemarks is passed as False - this will be passed all the way down through the recursive calls and so that line which calls .Remove never gets executed....the fact we don't see logging proves this....
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Feb 17, 2012
I am working on a project where I have a personnel class. The records stored in the class are populated a few records per second. At the time I am inserting the records, I have to check the same class to ensure the same record is not added twice. Since I am looping through the class using "For Each", I get a message "Collection was modified; enumeration operation may not execute".
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Mar 11, 2009
i'm getting the following error: "COLLECTION WAS MODIFIED; ENUMERATION OPERATION MAY NOT EXECUTE."
The stack trace is ;
at System.Collections.SortedList.SortedListEnumerator.MoveNext()
at SatcomDiscoverySocket.clsGatewaySend.SendViaGatewaySend() in C:Documents and Settingsjim.SATCOM_DOMAINMy DocumentsVisual Studio 2005ProjectsSatcom Discovery Socket ServerSatcomDiscoverySocketSatcomDiscoverySocketThread PollingclsGatewaySend.vb:line 60
The line in question is but I don't believe that to be true I think its the line above it;GatewaySendEntry = Nothing The code is below. I can't figure out why, it's causing the error at that line and how to fix it.
[Code]...
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Dec 21, 2011
I'm have a data management program. I've fixed everything in it, except when I run my Insert or update commands on a different computer I've installed it on, JIT tells me that the collection has be modified, it then gives me the option to continue or quit. I know it's been modified, the user knows it's been modified, how do I get rid of that?
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Oct 27, 2009
How can I create the property... type the combobox? for now I found alone this that it goes in mistake
[Code]....
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Oct 15, 2009
I have this flood-fill algorithm, based on a queue (I tried the recursive method but pictures are too big and it was causing stack overflow).The problem is that when it makes the second pass in the for-each loop, the program crashes and compiler gives me the message "Collection was modified; enumeration operation may not execute.".Well, of course I know the collection was modified (it supposed to be!) since I am adding necessary items to it on-the-fly within the loop. What I cannot understand is why it happens since the for-each is based on the remaining items in the collection and not in a numeric index.
Below, the actual code:
Code:
Public Sub FloodFill(ByVal myx As Integer, ByVal myy As Integer)
Dim icoord As coordinate
Dim ocoord As coordinate
[code]....
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Dec 29, 2011
This is what happened: on the form load of my application i created a background worker to bind collection (records from database filled in the dataset) on my control. but the problem is when the i updated the records on the database it throws an error if i run this procedure again.
If xControl.InvokeRequired Then
Dim MyDelegate As New InitializeDataBinding_Delegate(AddressOf InitializeDataBinding)
Invoke(MyDelegate, New Object() {xControl, xQuery, xPrimaryKey}) ' ERROR HERE SAYING: Collection was modified; enumeration operation may not execute.
[Code]...
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Oct 27, 2011
I'm getting a Collection was modified; enumeration operation may not execute error every time I try to close this form. I suspect it has something to do with the StringBuilder() which I have declared in the starting form (Details1). I have already spent hours looking for the problem. It does not throw an error when I debug, only when I install on other machines.
[Code]...
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Oct 15, 2011
I am encountering an error when looping through datarows. I searched SO and tried the solutions, but no luck. Collection was modified; enumeration operation might not execute.
Dim dRow As DataRow
For Each dRow In dt.Rows
dt.Rows.Add(dRow("CustNum"), dRow("SalesRepName"), dRow("mgrid"), "=""" & dRow("midValue") & """", dRow("dba"), dRow("sysDate"), dRow("statusID"))
Next
The error occurs the first time the code hits "Next". What would be causing Collection was modified; enumeration operation might not execute.How can I resolve this error?
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Nov 28, 2010
I have a multithreaded app that is throwing the following error.Collection was modified; enumeration operation might not execute.[code]I'm pretty sure the collection is being modified by another thread. I attempted to fix the problem with the SyncLock's but clearly I'm missing something here.I thought I could lock the object by properly using SyncLocks, am I just not locking the right object(s)? Or am I completely missing something here.Besides using SyncLocks what other options do I have to prevent this error. I was thinking perhaps a global variable to keep track critical code sections so that no 2 threads enter.I'm also a little confused about what collection is being modified my first guess was CLResultsDataTable. ResultsDataTable, but I'm not sure.This is an older project I just recently picked back up so I'm still stepping through a lot of code to try to figure out how/why this is happening
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Jun 25, 2011
I am trying to add the file information of the contents of a folder to a collection. Although I am getting the collection to hold the correct number of items that the folder contains, all of the collection's items are the details of the last file in the folder.
I'm trying to use a loop to go through each item contained in the folder and then adding the item details to a collection with the following line
nCounter += 1
collFileDetails.Add(NameOfItem, nCounter)
Next NameOfItem
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Apr 15, 2010
CAUTION: Noob using Win32 API ahead
I want to display a list of open windows on my computer in a rich text box. So, I'm trying to store the names of all windows in myString, and then set RichTextBox1.Text = myString.
Here's the code
Imports System
Imports System.Collections.Generic
Imports System.Collections.ObjectModel
[Code].....
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Jan 10, 2011
I'd like some help with this error that other users has when they launch the app I created. I will copy / paste the error
Tittle: Collection was modified; enumeration operation may not execute.
Error:
System.InvalidOperationException: Collection was modified; enumeration operation may not execute.
at System.Windows.Forms.Control.MarshaledInvoke(Control caller, Delegate method, Object[] args, Boolean synchronous)
at System.Windows.Forms.Control.Invoke(Delegate method, Object[] args)
[code].....
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Jul 27, 2007
I have looked at multiple posts regarding this issue, but can't seem to find a solution. To keep it simple I have an Access database with a single table. It does have a field as a primary key. When I click the save icon on the Binding Navigator I get this error having to do with the following code:
Me.Validate()
Me.TitlesBindingSource.EndEdit()
Me.TitlesTableAdapter.Update(Me.VFCurvesDataSet.Titles)
I cannot set the Refresh the Data Table check box in Advanced Options of the TableAdapter Configuration Wizard as it is grayed out. Once again, I have a primary key.
The posts I have reviewed indicate that an UpdateCommand needs to be created, but I can't understand how it should be done. W
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Nov 11, 2005
I get an error when I try to edit a cell that already containts data. What am I missing? be as explicit as I am very new at this.
[Code]...
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Jan 16, 2010
I'm trying to create an inherited version of the ListView control that (among other things) should have a different background image if the listview is empty to if it has items.Obviously you can easily enough test the count of the collection, but I need to be able to react to the event, however there doesn't appear to be any event related to adding/removing items.
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Jan 12, 2009
I'm working on building my own UserControl that will display thumbnails. I've got the collection and the items that the collection holds working ok, and I've got a handle on how I'm going to display the information on the face of the UserControl. However, my problem is how to fire the Method that displays the thumbnail on the face of the UserControl when a new Item is added to the Collection?
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Apr 3, 2012
I have an Inherited Control with a Property that can be set in the designer. There's some code in the Set procedure to make sure it's set appropriately. However when I build or run the project that property is changed, I am assuming it's the sanity check code in the Set procedure that's causing it to be changed along with some VS beahviour. Here's the code:
[Code]...
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Jul 30, 2009
I have a class that contains a collection of another class. See below
Public Class Spot
Private mActive As Boolean
Public Sub New()
[Code]....
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Jan 6, 2010
I want to retrieve the selected items in a listbox, save them to a collection, and then use that collection later. I thought that was simple enough, but when I clear the selected items in the listbox, my collections (items, indices) change. I found this out by stepping through the code.
Basically what I'm wanting to do is move items in the listbox up or down (up in this case), and still keep them selected.
[Code]...
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