Binding to DropDownList problems

[raphael232]

Hi, i'm having problems binding to the DropDownList control. Here's my code:

<asp:DropDownList ID="lstCategoryID" SelectedValue='<%# Eval("CategoryID") %>' DataTextField="Text" DataValueField="Value" runat="server">
</asp:DropDownList>

and here's my code behind (Page_Load event handler):

Dim lstCategoryID As DropDownList = CType(FormView1.FindControl("lstCategoryID"), DropDownList)

lstCategoryID.DataSource = Utilities.GetCategoriesList()
lstCategoryID.DataBind()

When i run the application i get the error:

'lstCategoryID' has a SelectedValue which is invalid because it does not exist in the list of items.
Parameter name: value

This seems a strange error since there is a value in the DropDownList which is the same as the value i am trying to bind to. I think it might be something to do with me loading in the contents of the DropDownList with the Page_Load event handler (since i have had no problems with dropdownlists with static options). I have also tried putting in the Page_Init event handler but this did not work either.

Appreciate if someone could help. Thanks

 

[vbkris]

>>SelectedValue='<%# Eval("CategoryID") %

will try to read the value from a field called "CategoryId" in the dataset returned by Utilities.GetCategoriesList() method.

why are u using eval there???


Known is handfull, Unknown is worldfull

 

[jendeacott]

As vbkris said, you dont need to use Eval there, set it when you bind the list in the code behind.

Dim lstCategoryID As DropDownList = CType(FormView1.FindControl("lstCategoryID"), DropDownList)

lstCategoryID.DataSource = Utilities.GetCategoriesList()
lstCategoryID.SelectedValue = "CategoryID"
lstCategoryID.DataTextField = "Text"
lstCategoryID.DataBind()

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