Hello mcseidl,

I have investigated this further and it seems that theClearDataSource issue occurs only when having a header template for a column and a DropDownProvider bind through the DataSourceID property. I have therefore asked our engineers to examine this matter further. To ensure that it will receive attention, I have logged this behavior in our internal tracking system with a Development ID of 131790. The next step will be for a developer to review my investigation and confirm my findings or to offer a fix, or other resolution.

I will leave this case open and update you with any new information after the review.  You can also continue to send updates to this case at any time.

You can view the status of the development issue connected to this case by selecting the "Development Issues" tab when viewing this case on the web site. 

Please let me know if you need more information.

Thanks.

Hello mcseidel,

Thank you for your replies.

Regarding getting a reference to the template dropdown - as you have noted the header templates would not be instantiated until the grid is databound. Binding the grid 2 times should be OK in this case.

I have been examining the issue occurring when ClearDataSource is being called and the reason for the exception seems to be somehow related to the providers defined in the grid. In order to be certain I will need to examine this some more.

I will keep you posted of my progress. In the meantime, please do not hesitate to contact me with any updates or additional questions.

Another thing is the original error that I"m experienced - "Multiple controls with the same ID 'Header1' were found. FindControl requires that controls have unique IDs. '

in this particular case was caused by   whdg.GridView.ClearDataSource();.. what else could cause this error, who creates this headers .. I've got this error intermittently on other occasions.

Thanks

Thanks, it did work for me. Before closing case I would like to clear couple of questions :

1. //get a reference to the dropdown. Note that the template controls may not be instantiated before databinding
        WebDropDown templatedDropdown = (WebDropDown)whdg.GridView.Columns["Account"].Header.FindControl("wddHeaderFilters");

Actually it is not instantiated before data binding, so on post back and since I need to retrieve value before setting fitter to my source I have to use some other facilities to get filter value ( such as old hidden var.. )  But if I really need to retrieve value on post back, should just bind it twice ?

2. on wddFilters_SelectionChanged I'm taking my data source and set filter so only some rows are visible for databind

What is the correct sequence ?I used the following :

        whdg.GridView.ClearDataSource();
       whdg.GridView.Rows.Clear();

        ExhibitLR2MasterDS MasterDS = (ExhibitLR2MasterDS)Session["LR2MasterDS"];
        ExhibitLR2MasterDS.MasterTableDataTable mdt = MasterDS.MasterTable;
        mdt.DefaultView.RowFilter = ((WebDropDown)sender).SelectedValue;
        whdg.DataSource = MasterDS;
        whdg.DataBind();
        whdg.GridView.RequestFullAsyncRender();

You mentioned that whdg.GridView.ClearDataSource();  messing things up so it's removed. You also commented out whdg.GridView.Rows.Clear();  but it does not work properly without this line.  So what is the exact set of command ( I have several places like this) to rearrange data source and display limited number of rows on the post back.