Databinding methods such as Eval(), XPath(), and Bind() can only be used in the context of a databou

O

Owen Blacker

I've spent loads of time Googling to try to work this one out and I'm
sure it's something obvious.

I get an InvalidOperationException reading "Databinding methods such as
Eval(), XPath(), and Bind() can only be used in the context of a
databound control" when I start my page. Unless I'm missing something
obvious, this is *not* the same issue as the "2-way databinding
cascading lists" issue in
http://www.webswapp.com/codesamples/aspnet20/dependentlists/default.aspx
(which is linked from everywhere; I kinda wish that were my problem ;o)

I have a templated databound custom server control, that I've built
with
a great deal of help from the two articles by 4GuysFromRolla's Scott
Mitchell (http://masl.to/?S11823B6D and http://masl.to/?P40821B6D, both
on msdn.microsoft.com).

I don't seem to be able to use databinding syntax, however:

<ItemTemplate>
<asp:TableCell runat="server"><%# Eval("First")
%></asp:TableCell>
...
</ItemTemplate>

bound to a List<Pair> gives me an exception:

[InvalidOperationException: Databinding methods such as Eval(),
XPath(),
and Bind() can only be used in the context of a databound control.]
System.Web.UI.Page.GetDataItem() +90
System.Web.UI.TemplateControl.Eval(String expression) +110
ASP.owentest_aspx.__DataBind__control8(Object sender, EventArgs e)
in
c:\Projects\Customisation\RedesignProtoTypeWeb\Owentest.aspx:13
System.Web.UI.Control.OnDataBinding(EventArgs e) +80
System.Web.UI.Control.DataBind(Boolean raiseOnDataBinding) +198
System.Web.UI.Control.DataBind() +12
System.Web.UI.Control.DataBindChildren() +214
System.Web.UI.Control.DataBind(Boolean raiseOnDataBinding) +208
System.Web.UI.Control.DataBind() +12
System.Web.UI.Control.DataBindChildren() +214
System.Web.UI.Control.DataBind(Boolean raiseOnDataBinding) +208
System.Web.UI.Control.DataBind() +12
uSwitch.Web.UI.Lego.RepeatingInputRow.CreateItem(Int32 rowIndex,
Table container, Boolean useDataBinding, Object rowData) in

C:\Projects\uSwitch.Web\UI.Lego\InputModule\RepeatingInputRow.cs:361
uSwitch.Web.UI.Lego.RepeatingInputRow.CreateControlHierarchy(Boolean
useDataBinding) in

C:\Projects\uSwitch.Web\UI.Lego\InputModule\RepeatingInputRow.cs:452
uSwitch.Web.UI.Lego.RepeatingInputRow.DataBind() in

C:\Projects\uSwitch.Web\UI.Lego\InputModule\RepeatingInputRow.cs:643
Owentest.Page_Load(Object sender, EventArgs e) in

c:\Projects\Customisation\RedesignProtoTypeWeb\Owentest.aspx.cs:20
System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object
o, Object t, EventArgs e) +13
System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object
sender, EventArgs e) +45
System.Web.UI.Control.OnLoad(EventArgs e) +80
System.Web.UI.Control.LoadRecursive() +49
System.Web.UI.Page.ProcessRequestMain(Boolean
includeStagesBeforeAsyncPoint, Boolean
includeStagesAfterAsyncPoint) +3716

I don't get the exception if my databinding control is outside the
table
cell but, for a handful of other reasons, including that my
ItemTemplate
is being instantiated inside a TableRow, that won't work for me.

Any ideas gratefully received, as I'm completely lost.


Owen
 
P

Phillip Williams

Owen,

Can you post the entire page code that causes this problem?
--
HTH,
Phillip Williams
http://www.societopia.net
http://www.webswapp.com


Owen Blacker said:
I've spent loads of time Googling to try to work this one out and I'm
sure it's something obvious.

I get an InvalidOperationException reading "Databinding methods such as
Eval(), XPath(), and Bind() can only be used in the context of a
databound control" when I start my page. Unless I'm missing something
obvious, this is *not* the same issue as the "2-way databinding
cascading lists" issue in
http://www.webswapp.com/codesamples/aspnet20/dependentlists/default.aspx
(which is linked from everywhere; I kinda wish that were my problem ;o)

I have a templated databound custom server control, that I've built
with
a great deal of help from the two articles by 4GuysFromRolla's Scott
Mitchell (http://masl.to/?S11823B6D and http://masl.to/?P40821B6D, both
on msdn.microsoft.com).

I don't seem to be able to use databinding syntax, however:

<ItemTemplate>
<asp:TableCell runat="server"><%# Eval("First")
%></asp:TableCell>
...
</ItemTemplate>

bound to a List<Pair> gives me an exception:

[InvalidOperationException: Databinding methods such as Eval(),
XPath(),
and Bind() can only be used in the context of a databound control.]
System.Web.UI.Page.GetDataItem() +90
System.Web.UI.TemplateControl.Eval(String expression) +110
ASP.owentest_aspx.__DataBind__control8(Object sender, EventArgs e)
in
c:\Projects\Customisation\RedesignProtoTypeWeb\Owentest.aspx:13
System.Web.UI.Control.OnDataBinding(EventArgs e) +80
System.Web.UI.Control.DataBind(Boolean raiseOnDataBinding) +198
System.Web.UI.Control.DataBind() +12
System.Web.UI.Control.DataBindChildren() +214
System.Web.UI.Control.DataBind(Boolean raiseOnDataBinding) +208
System.Web.UI.Control.DataBind() +12
System.Web.UI.Control.DataBindChildren() +214
System.Web.UI.Control.DataBind(Boolean raiseOnDataBinding) +208
System.Web.UI.Control.DataBind() +12
uSwitch.Web.UI.Lego.RepeatingInputRow.CreateItem(Int32 rowIndex,
Table container, Boolean useDataBinding, Object rowData) in

C:\Projects\uSwitch.Web\UI.Lego\InputModule\RepeatingInputRow.cs:361
uSwitch.Web.UI.Lego.RepeatingInputRow.CreateControlHierarchy(Boolean
useDataBinding) in

C:\Projects\uSwitch.Web\UI.Lego\InputModule\RepeatingInputRow.cs:452
uSwitch.Web.UI.Lego.RepeatingInputRow.DataBind() in

C:\Projects\uSwitch.Web\UI.Lego\InputModule\RepeatingInputRow.cs:643
Owentest.Page_Load(Object sender, EventArgs e) in

c:\Projects\Customisation\RedesignProtoTypeWeb\Owentest.aspx.cs:20
System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object
o, Object t, EventArgs e) +13
System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object
sender, EventArgs e) +45
System.Web.UI.Control.OnLoad(EventArgs e) +80
System.Web.UI.Control.LoadRecursive() +49
System.Web.UI.Page.ProcessRequestMain(Boolean
includeStagesBeforeAsyncPoint, Boolean
includeStagesAfterAsyncPoint) +3716

I don't get the exception if my databinding control is outside the
table
cell but, for a handful of other reasons, including that my
ItemTemplate
is being instantiated inside a TableRow, that won't work for me.

Any ideas gratefully received, as I'm completely lost.


Owen
 

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