problem with DataGrid1.AllowSorting = true;

Question

Hi I am observing a weird thing here ! I generate my datagrid columns programatically (the columns depend on some conditions) and for that I have to do something like this : DataGrid1.AutoGenerateColumns = false; DataGrid1.AllowSorting = true; BoundColumn col = new BoundColumn(); col.HeaderText=Date; col.DataField=insert_date; col.DataFormatString = {0:d}; col.ItemStyle.Wrap = false; col.SortExpression = Date; DataGrid1.Columns.Add(col); But my sorting does not work if the line: DataGrid1.AutoGenerateColumns = false; is present. If I comment out this line of code then the sorting works - that too for some of the columns and not all. Also I observed that by having this line in my code the program execution (most probably) does not even enter the DataGrid1_SortCommand(...) method ! I am lost if someone can shed some light it would be great. Waiting -Apurva.

MrsWhitl · Answer

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valsume · Answer

I had a similar problem and even though I am not adding columns programatically just adding this statement SortExpression=Author to the web page Column statement enabled the the column heading to respond to clicks and cause sorting. I had to add programatic code to enable alternating ASC/DESC sorting but all an all that SortExpression statement was what was needed.

tsuman_in · Answer

It will generate columns at runtime and allow you to sort I tested after having problems doing it the way you were. I thought I was going to have to add events on-the-fly but once I moved it to OnInit everything worked fine. The div tag thing won't work successfully it's not really successfully in regular html. You could have it add the div tag after the first item is added but I can't guarantee anything.

apurva · Answer

Hi Suman I have yet to try it but just confirming with you : Do you mean that if I add the column creation code in the Page::OnInit and add the autogencolumns and allowsort to the actual xml then will I get the expected behaviour of : 1) Generating columns at runtime AND 2) be able to sort the columns using the already provided EventHandler Also when I use the DIV tag to have scrollbars on the datagrid the header scrolls up while moving the scrollbar (Vertical). Do you know of some way in which I can have the header freeze right there and only the rows move - and at the same time the header columns being able to perform the sort whcih clicked upon ? Awaiting your reply Thanks a lot -Apurva.

tsuman_in · Answer

I ran a test and ran through the events trying to recreate your problem and had the same problem. Then I remembered that you can't add columns to a datagrid properly unless you add them during Page::OnInit. Also you may as well move the autogencolumns and allowsort to the actual xml it's not buying you anything to add it in the code. So move your column creationg code into the InitializeComponent function but note that VS.NET will automatically try to remove anything you put into InitComponent. You may have to readd it several times. There is a patch but you have to call support for it and it's not worth the hassle. private void InitializeComponent { this.DataGrid1.SortCommand += ... this.Load += ... CreateDataGrid1Columns(); } private void CreateDataGrid1Columns() { BoundColumn col = new BoundColumn(); col.HeaderText=Date; col.DataField=insert_date; col.DataFormatString = {0:d}; col.ItemStyle.Wrap = false; col.SortExpression = Date; DataGrid1.Columns.Add(col); }

apurva · Answer

Hi Suman I am certainly binding the data to my grid but my confusion is that if I make AutoGenerateColumns=false then on clicking the header of the column the event handler functon is not even called ! Sorting will take place only if that function is called. Also if you could elaborate on your post that would be great - seems like it has some deep hidden meaning which I am not able to comprehend. Awaiting your reply Thanks Suman -Apurva.

tsuman_in · Answer

Where is your DataGrid.DataBind() in all of this? Everything revolves around that statement. Remember the DataGrid is useless until the DataBind() method is called. Before the DataBind method there is the PrepareControlHierarchy which sets up the databinding that you are requiring so you must make all your changes beforehand.