Issue binding a DataTable to an ASP.Net GridView control - asp.net

Question

I'm trying to allow my users to enter in large lists of data using an ASP.Net GridView control. The affect I'm trying to create is to make the GridView control act like a spreadsheet. The user can freely enter data and tab from column to column and row to row. The user can use a button at the bottom of the page to add rows as needed. There is also a button at the bottom of the form to save as needed.
To do this, I created a DataTable with a bunch of empty rows and bound it to a GridView. The GridView's columns are template columns that contain textboxes. So, when the page opens, it actually looks like a spread sheet. When the user hits the add rows button, I just add another ten rows to the DataTable the GridView is bound to and it works like a charm.
The issue I'm running into is reading the data that the user entered. When the user hits the paging link or the update button, I would like to update the DataTable with the data the user typed in. Here is what I have.
Private Sub UpdateDataTable()
Dim objCatRow As clsCategoriesRow = Session("gvCategoriesRow")
Dim drQuery() As DataRow = Nothing
Dim drRow As DataRow = Nothing
Dim objRow As GridViewRow = Nothing
Dim intRecNo As Integer = 0
Dim txt As TextBox = Nothing
Dim lbl As Label = Nothing
'Loop through all of the rows in the grid view control
For Each objRow In Me.gvCategories.Rows
'Get the label that contains the identity column
lbl = objRow.Cells(GridColumns.Category).FindControl("lblItemRecNo")
intRecNo = lbl.Text
'Update the datarow bound to this grid view row
'First, query the datarow from the data table
drQuery = objCatRow.Table.Select("recno = " & intRecNo)
'Make sure our query returned a row
If Not IsNothing(drQuery) AndAlso drQuery.Count > 0 Then
'Get the value from the textbox in the grid view
txt = objRow.Cells(GridColumns.Category).FindControl("txtItemCategory")
'Upadte the data row with the value the user entered
'THE VALUE IN txt.Text IS EMPTY. HOW CAN I GET THE VALUE THE USER TYPED IN?
drQuery(0)("Category") = txt.Text
'Get the value from the textbox in the grid view
txt = objRow.Cells(GridColumns.SortORder).FindControl("txtItemSortOrder")
'Upadte the data row with the value the user entered
drQuery(0)("sortorder") = txt.Text
End If
Next
End Sub
The issue is that this is not returning what the user typed in. The line
txt = objRow.Cells(GridColumns.Category).FindControl("txtItemCategory")
returns a reference to the textbox in the templated column. But, it contains the previous value, the value from the view state, not the value the user typed in.
How can I get the value the user typed into the grid?
I want to mention that I know how to add EDIT and UPDATE buttons to each row. I would like to avoid doing that way if I can. My users have huge lists of data to enter in and that approach would make the application unusable.
Thanks in advance,
Mike

Answer 1

The form data posted by the user is found in the Page.Request.Form.Item collection. The Page.Request.Form.AllKeys lists the "keys" associated with all of the form item values.
If Page.Request.Form.HasKeys Then
For Each key as String In Page.Request.Form.AllKeys
' step through the keys and use Page.Request.Form.Item(key) to get the data entered
Next
end If
After testing, I was able to get the data from the Request.Form data or the GridView control during page.load on postback, as long as you don't bind the control on postback, but only during the initial request ("GET").
Keep in mind, controls have to be re-created for each request to the page. The Request data posted is used by ASP.NET to repopulate form data controls only after the controls are re-created on the page and the ViewState for the controls is processed, etc.
Request.Form collection
ASP.NET Page Life Cycle

Answer 2

You should replace this:
txt = objRow.Cells(GridColumns.Category).FindControl("txtItemCategory")
with this
txt = objRow.Cells(GridColumns.Category).FindControl("txtItemCategory").Value