enrique_aeo
asked on
export to excel from datagrid - object reference not set to an instance of an object - datagrid is null
i have this code
Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
'// Disable paging
GridView1.AllowPaging = False
'// exluded columns arraylist
Dim defaultExcludedColumns As New ArrayList()
'// Always exclude these columns
defaultExcludedColumns.Add
'// Send to base Excel export method
ExportGridView(GridView1, "Excel-Name", defaultExcludedColumns)
'// Rebind with paging enabled
GridView1.AllowPaging = True
End Sub
before calling this method ExportGridView need to validate that the GridView1 has at least one row
exportarERRORgridNULL.jpg
Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
'// Disable paging
GridView1.AllowPaging = False
'// exluded columns arraylist
Dim defaultExcludedColumns As New ArrayList()
'// Always exclude these columns
defaultExcludedColumns.Add
'// Send to base Excel export method
ExportGridView(GridView1, "Excel-Name", defaultExcludedColumns)
'// Rebind with paging enabled
GridView1.AllowPaging = True
End Sub
before calling this method ExportGridView need to validate that the GridView1 has at least one row
exportarERRORgridNULL.jpg
ASKER
THE GRIDVIEW IS NOTHING, VIEW FILE
but I need to validate if the datagrid has data before calling
ExportGridView (GridView1, "Excel" Name ", defaultExcludedColumns)
gridNULL.jpg
but I need to validate if the datagrid has data before calling
ExportGridView (GridView1, "Excel" Name ", defaultExcludedColumns)
gridNULL.jpg
The problem is in your If statement.
When you say (reading from your screenshot):
If grdView.HeaderRow isNot Nothing And GrdView.HeaderRow.Cells IsNot Nothing Then
the program actually checks BOTH statements in the IF clause. But, if HeaderRow is nothing, then HeaderRow.Cells causes the "Object not referenced to an instance of an object).
What you need to do is to use AndAlso, specifically:
If grdView.HeaderRow isNot Nothing AndAlso GrdView.HeaderRow.Cells IsNot Nothing Then
With this syntax, the code will check the first and only if it is true, it will move to the second. So, If HeaderRow is Nothing, it will never check for HeaderRow.Cells and no error will be raised.
When you say (reading from your screenshot):
If grdView.HeaderRow isNot Nothing And GrdView.HeaderRow.Cells IsNot Nothing Then
the program actually checks BOTH statements in the IF clause. But, if HeaderRow is nothing, then HeaderRow.Cells causes the "Object not referenced to an instance of an object).
What you need to do is to use AndAlso, specifically:
If grdView.HeaderRow isNot Nothing AndAlso GrdView.HeaderRow.Cells IsNot Nothing Then
With this syntax, the code will check the first and only if it is true, it will move to the second. So, If HeaderRow is Nothing, it will never check for HeaderRow.Cells and no error will be raised.
ASKER
I was thinking of something like this
If (gvwQryInscripciones.Rows.
ExportGridView(gvwQryInscr
End If
you think?
If (gvwQryInscripciones.Rows.
ExportGridView(gvwQryInscr
End If
you think?
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ASKER
it is OK
If so, your problem is that you are overriding the response, thus the gridview lost its contents.