Databinder inside a "for" loop in an ASPX page

Question

I'm still trying to understand how I can take advantage from DataBinder ( Is there a way to use a DataBinder.Eval statement as an index of a specific array in an ASPX page? ).

I'm currently building tables with the help of repeater and I would like to use a loop defining the Item label dynamically, to allow more interactions.

Currently, this test code is working:

<asp:Repeater id="Fish" runat="server">
<table>
<ItemTemplate>
  <tr>
    <td><%# Container.DataItem("ITEM")%></td>
    <td><%# Container.DataItem("AGG")%></td>
  </tr>
</ItemTemplate>
</table>
</asp:Repeater>

But as you can imagine, this type of structure doesn't allow to choose dynamically the columns that are displayed from the columns to be ignored.

I was thinking that by using a "for" loop structure, I would be able to choose dynamically which column could be displayed. And I tried this as a test:

Public Test_id() As String
Public Test_idp As String

<% Test_id = New String() {"id", "Agg"} %>
<asp:Repeater id="Fish" runat="server">
<table>
<ItemTemplate>
  <tr>
    <% For Each Test_idp as String In Test_id%>
      <td><%# Container.DataItem(Test_idp)%></td>
    <% Next Test_idp%>
  </tr>
</ItemTemplate>
</table>
</asp:Repeater>

which is not working... and is granted by the following error message:

Overload resolution failed because no Public 'Item' is most specific for these arguments:

'Public Overrides ReadOnly Property Item(name As String) As System.Object': Not most specific.

'Public Overrides ReadOnly Property Item(i As Integer) As System.Object': Not most specific.

Any idea?

Edit:

to answer Mike C's question, I have tried DataBinder.Eval(Container.DataItem, Test_idp) instead of Container.DataItem(Test_idp). It still does not work, but the error is different:

System.ArgumentNullException: value cannot be null

Instead of `Container.DataItem(Test_idp)` have you tried `DataBinder.Eval(Container.DataItem, Test_idp)`? — mclark1129, Aug 20 '12 at 15:45
@MikeC I have just tried it - it doesn't work and the error is different. I've updated the description of my example — S3MP, Aug 20 '12 at 15:55

score 2 · Answer 1 · answered Aug 20 '12 at 15:09

2

Test_Idp is an Object (since it wasn't declared otherwise).

Therefore, the compiler cannot figure out which of those overloads to call.

You need to explicitly declare it As String.

answered Aug 20 '12 at 15:09

SLaks

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I should have added that I have declared both Test_id and Test_idp as string: Public Test_id() As String and Public Test_idp As String – S3MP Aug 20 '12 at 15:15
@S3MP `Test_idp` is NOT declared as a string in your code example. If you have changed it since then, then you need to update your example so that it says `For Each Test_idp As String...`. – mclark1129 Aug 20 '12 at 15:22
@MikeC Ok sorry - example updated - tested - still the same error – S3MP Aug 20 '12 at 15:28

score 0 · Answer 2 · answered Aug 20 '12 at 15:17

You can use a nested repeater for the columns.

<asp:Repeater id="Fish" runat="server">
<table>
<ItemTemplate>
  <tr>
    <asp:Repeater id="columns" runat="server">
        <ItemTemplate>
          <td><%# ((RepeaterItem)Container.Parent.Parent).DataItem("ITEM")%></td>
          <td><%# ((RepeaterItem)Container.Parent.Parent).DataItem("AGG")%></td>
        </ItemTemplate>
    </asp:Repeater> 
  </tr>
</ItemTemplate>
</table>
</asp:Repeater>

Databinder inside a "for" loop in an ASPX page

2 Answers2