GridView column losing hyperlink when looping through rows - asp.net

Question

I have an asp.net page written with vb.net that has a gridview table. The table is setup to have a checkbox column for each row. If this checkbox is checked for a row, I do some additional things. One of the other columns also includes a hyperlink on the text for each cell in that column.
I have a button on the page that will loop through and programmatically check each one of the checkboxes. The button does this correctly; however, it also removes the hyperlink from the other column for some reason. Any ideas why?
Here is the code where I set the hyperlinks for the hyperlink column:
Protected Sub gridData_RowDataBound(sender As Object, e As GridViewRowEventArgs) Handles gridData.RowDataBound
'When a row is added to the data grid view we need to add the hyperlink to the zipname column
If e.Row.RowType = DataControlRowType.DataRow Then
Dim cell As TableCell = e.Row.Cells(4)
Dim lnk As HyperLink = New HyperLink
'Set properties of the link
lnk.NavigateUrl = cell.Text
lnk.Text = cell.Text
'Format the filename, filepath, zipname, and username to be lowercase
e.Row.Cells(1).Text = LCase(e.Row.Cells(1).Text)
e.Row.Cells(3).Text = LCase(e.Row.Cells(3).Text)
e.Row.Cells(4).Text = LCase(e.Row.Cells(4).Text)
e.Row.Cells(5).Text = LCase(e.Row.Cells(5).Text)
'Add the hyperlink
cell.Controls.Clear()
cell.Controls.Add(lnk)
End If
End Sub
Here is the code for the check all button:
Protected Sub cmdCheckAll_Click(sender As Object, e As EventArgs) Handles cmdCheckAll.Click
'Check all of the download checkboxes
For Each row As GridViewRow In gridData.Rows
CType(row.FindControl("CheckBox1"), CheckBox).Checked = True
Next
End Sub

Answer 1

As is the usual case with Dynamic Controls, All the dynamically created Hyperlinks in RowDataBound event needs to be recreated every postback.
So, there are 2 options.
1.) Either bind your GridView on every postback :
protected void Page_Load(object sender, EventArgs e)
{
gridData.DataBind();
}
OR
2.) Turn off ViewState for your GridView::
<asp:GridView ID="gridData" EnableViewState="false" ... />.
On using any of above options, the OnRowDataBound event is executed each time postback happens, thus recreating the Dynamic controls. Now you can access the Hyperlinks in your button click event.
Check properly which one of above options is best for your application.