Forms :: Et The Datasource On A ComboBox On A WinForm To Use The Above Collection?
Aug 3, 2011
I have a custom collection which is derived from a base class implementing IEnumerable and IEnumerator, this collection is populated with custom objects.I'm trying to set the datasource on a ComboBox on a WinForm to use the above collection - but when the code is run the ComboBox is always empty.
The code I was using was this:
Private Sub ViewSources_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
' declaration
Dim sourceCollection As SourceCollection
Dim source As Source
I have a 2 classes, one is Employee, the other is Employees. Basically Employees is a collection of Employee, I have a combo box where the Datasource is Employees.
When the user selects a value from the combo box, How do I get an Employee object from whatever is selected?[code...]
I could hard-code in the column names ("WO_Number",WO_CustID","CustLastName", etc...), but would prefer to pick this up dynamically (partly because I want to reuse this code later).
I have a list of Active Directory entries (computer names) as a Collection data type. How can I add the computer entries and the pertinent columns to the DataGrid control on my WinForm? I have borrowed this code from some web site to add the list of computer to the pcList which is a Collection type. pcList.Add(dirSearchResults.GetDirectoryEntry().Name.ToString())
I have two combo boxesthat use the same collection for their datasource. The data member and value member are also the same properties. When the form loads, and I select an item in one of the combo boxes, the same item is then selected in the other combo box. I want the combo boxes to work separately. Do I need to have two different collections, even though they would have the same data in them?
Here's the scenario, winforms application, monitoring via Task Manager Processes Tab.On initial launch spins up to ~61,000K (initial data grid and data loads)If I minimize the application, not touching or doing anything the Mem usage drops to 1,380K.When I restore the application is spins back up to only 5.8K
So my question is, does the minimize send some internal message to clean up resources since the application in question is not in focus?The first app I noticed this in happens to be VB.NET, but I've observed the same behavior in my main C# winform applications.
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.
I am customizing a DataGridView control. The DataGridView is supposed to be bound to a collection of some type (be it a List(Of T) or ArrayList or whatever), and the idea is that one can easily determine (at design-time in this case) which properties of the type have to be shown in the grid and which column header name they should get. One can do this using an attribute. For example, if I have a class Person with Name, Age and HairColor and I don't want to show the HairColor property, and want to show the Name property as 'Person', I would use:
vb.net Public Class Person <Grid.GridOptions(displayName:="Person", visible:=True)> _ Public Property Name As String
[code]....
I do this during run-time by simply looping through the properties of the bound type (in this case Person), retrieving the GridOptions attribute (if any) and checking the values provided. This works just fine except for one thing: I'm not really sure how to determine the type in the databound collection...
At the moment, I cast the DataSource property to an IList and retrieve the type of the first instance in that list (if any). If there isn't a first instance (the list is empty) then I don't know how to get the type... Often I know that it will be impossible to know the type. If someone is binding an ArrayList for example, then it's impossible to know what kind of items he's going to put in that ArrayList. Even the normal DataGridView cannot show any columns when databound to an empty ArrayList. However, the framework's DataGridView does show the columns when bound to, for example, an empty List(Of Person), or a Person array.
I'm pretty sure that casting the DataSource to an IList is not the correct way as all information about the type of items in that list is then lost. But I'm not sure what else to cast it to... ITypedList? IBindingList? I even considered List(Of T) because that's all I am going to be using, but besides the fact that the grid would then obviously only work for a List(Of T) I still don't know how to do this... I don't know 'T' so I can't cast it to a List(Of T)...
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????
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.
I'm just a beginner at VB.NET...I want to be able to insert a combobox control onto my form through code but I'm not sure how. Google doesn't seem to answer.
Something along the lines of (I have no idea) Me.AddControl("Combobox")
I would obviously then need to set the properties to setup the position/size etc.
When my form loads, before the ComboBox has been populated and selected this Event (SelectedIndexChanged) gets triggered. How can I prevent the code insides this Event from Executing before form has completely loaded? I tried testing for .SelectedIndex but it returns 0.
I have defined a datagrid which has combobox in one of the columns, is there anyway to modify the datasource of the combobox (the source of the list) at run time?
I am trying to get the valuemember of my combobox but it just won't work. I have tried a lot of things (won't post them all here) can somebody just show me how to do this?
Private Sub cmbGroup_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles cmbGroup.SelectedIndexChanged ' Get valuemember here End Sub
I have a ComboBox that is bound to a List(of T).Now I type-cast the ComboBox.DataSource into List(of T)and add some more elements in the List.The items collection of the ComboBox doesnt get reflected and the new element does not show up in the ComboBox. Am I missing something ?
Private Sub UsernameEdit_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load Dim sqlconn As New SqlConnection sqlconn.ConnectionString = "stuff"
[code]....
The combobox just populates with "System.Data.DataRowView" I know it is some command to read the correct data out of the table, is it setting up something like:
dim i as integer for i = 0 to CompanyNames.length-1 companyadapter.fill(companynames.rows(i)] next
just curious what happens when i set the datasource of a combobox or datagrid or what-not to a dt then when i want to change what's in the combobox etc., i just set the datasource to a new one. i am cleaning as i go but just want to know what happens to the old datasource:
I have a combobox which i am binding to a sortedDictionary list, so it displays in ascending order. My question is, I need to display "--Select--" as the first option. Is there any way to either:
1) add another item besides for the datasource
or
2) add an unsorted item to the top of the sortedDictionary
I have to add item "Final Grade" to my cboQuarter. The thing is, my cboQuarter already has a datasource and I can't add the item "Final Grade" during drop-down. The error says, "cannot modify or insert (can't remember word by word) when it already has a datasource."
Appropriate Title would be: Bind comboBox Tag to database.I have a comboBox on form which is bounded but and I need to populate it manually. With some reading on net i have found a way but it is not working
I can populate my combo, select item in combo, update database but the problem is when I load my form it displays empty combo (combo is fulled with my custom data but nothing is selected it must select correct ItemText) and after selecting a value in combo, the value disappears as soon as combo losses focus .
Is it possible to BOTH set a comboboxes datasource AND databind the selected value?Ihave 2 comboboxes on a form that I want to populate with data from 1 table,ut I want the actual selected values on each of the comboboxes to come from separate columns n another datasource Right now if one combobox changes, so does the other if that makes sense.
Here's a sample of code: 'Bind DataSource With cboYields
With code above, how do I assign the value to the combobox while retrieving data from the table so that it point to the corresponding combobox item. For example, if the value of status_ID is 1 then the combobox should show "completed" in the datagridview.
I am using code similar to this to populate a combobox with items from a database. The display works fine, but when I try to get the combobox.SelectedValue it is returning a DataRowView, where I need an integer. Obviously this is becuase I haven't casted the value to an integer, but the function, CInt(cboPosition.SelectedValue) is throwing an InvalidCastException. Is there any way that I can get the ValueMember's type to be an Integer?
Dim cn As New SqlConnection(CreditDisputesLogConn) Dim cmd As New SqlCommand("CustomersLookup", cn) Dim da As New SqlDataAdapter(cmd)
How can I get an item value from a Combobox using a datatable as it's datasource? Here's my code for constructing the combobox. This code works, that's why I'm not showing it all, but I want you to know how I'm creating the combobox.
Try query = "SELECT category_id, name FROM categories ORDER BY name ASC;" dbCommand = New MySqlCommand(query, dbConnection)
[Code]....
I want to display what is the item you physically see in the combobox that you select.
I have this controls ComboBox: list of myobject TextBox: view a description DataSource: list(of MyObject) MyObject:
property id as int property combodesctription as string property description as string
What I want: I set the datasource of combobox with list of MyObject when I select a value on combobox, I would like see description in TextBox is it possible bound text property of TextBox to same datasource of combobox or it is possible change description of TextBox only with changedEvent of ComboBox?
I have a ComboBox which is bound with a DataSource from (obviously) a Database. However, there are 659 different entries inside this Database and I was hoping to tack on AutoComplete.
I tried setting the Source to the ListItems since, after initialization and the data is bound, all the items necessary are in fact inside the ComboBox so I had assumed that it would pick that up. I was wrong. I tried using a Custom source but VS errored out saying that I couldn't do that since the ComboBox was bound.
My question is, how can I utilize AutoComplete's "Suggest" mode with a bound ComboBox?
