while saving data from data gridview to table getting error:'Object reference not set to an instance of an object"

Question

i am working on vb.net windows form ,I have a data grid view,,i am trying to save data grid values

I am saving data to Two Tables..my Table Names:

1->CompanyMaster_tbl
2->DepartmentMaster_tbl

I given code in save button like this:

Dim CompanyMaster_tbl As DataTable = Nothing
        Dim DepartmentMaster_tbl As DataTable = Nothing

        For Each CompanyMaster_row As DataRow In CompanyMaster_tbl.Rows
            For i As Integer = 0 To gv.RowCount - 2

                If gv.Rows(i).Cells("cmpny").Value <> "" Then
                    sqlInsertT1 &= "Insert Into CompanyMaster_tbl(CompanyName) Values ('" & gv.Rows(i).Cells("cmpny").Value & "');"
                    Exetransaction(sqlInsertT1)
                End If
                Ccid = RecordID("Cid", "CompanyMaster_tbl", "CompanyName", gv.Rows(i).Cells("cmpny").Value)
            Next

            For Each DepartmentMaster_row As DataRow In DepartmentMaster_tbl.Select(Ccid)
                For j As Integer = 0 To gv.RowCount - 2
                    sqlInsertT2 &= "Insert Into DepartmentMaster_tbl(dtname,dtphone,dtEmail,Cid) Values ('" & gv.Rows(j).Cells("Dpmnt").Value & "','" & gv.Rows(j).Cells("dtphon").Value & "','" & gv.Rows(j).Cells("mail").Value & "'," & Ccid & ");"
                    Exetransaction(sqlInsertT2)
                Next
            Next
        Next

while coming to this line am getting error:

For Each CompanyMaster_row As DataRow In CompanyMaster_tbl.Rows

Object reference not set to an instance of an object why i am getting this error? what is wrong with my code

in such case your CompanyMaster_tbl is null and that's why when you do .Rows it's throwing null ref exception. You might want to check CompanyMaster_tbl — Rahul
– Rahul, Commented Jan 2, 2014 at 13:23
Well given what you are doing I'd have expected your table to be pointing at a table in a data set pointed at a connection. Certainly making it Nothing and then trying to use it isn't going to work. — Tony Hopkinson
– Tony Hopkinson, Commented Jan 2, 2014 at 13:29

Rahul · Accepted Answer · 2014-01-02 13:45:55Z

1

I don't work in VB.NET (rather in C#) but your code make no sense.

You saying ...

Dim CompanyMaster_tbl 
As DataTable = Nothing <-- (here CompanyMaster_tbl set to null)


        For Each CompanyMaster_row As DataRow 
       In CompanyMaster_tbl.Rows <-- you are trying to referencing it.

So, it will definitely throw you null reference exception.

Instead of saying ...

For Each CompanyMaster_row As DataRow In CompanyMaster_tbl.Rows

Why not loop through rows in your gridview and then populate the datatable

For Each DataGridViewRow gr In gv.Rows

      If gr.Cells("cmpny").Value <> "" Then
            sqlInsertT1 &= "Insert Into CompanyMaster_tbl(CompanyName) 
            Values ('" & gr.Cells("cmpny").Value & "');"
            Exetransaction(sqlInsertT1)
        End If
        Ccid = RecordID("Cid", "CompanyMaster_tbl", "CompanyName", 
        gr.Cells("cmpny").Value)
    Next

edited Jan 2, 2014 at 13:45

answered Jan 2, 2014 at 13:26

Rahul

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6 Comments

user3106114 Over a year ago

it is oke sir,,,so how i can save data from gridview to mutilpe tables

aaroncatlin Over a year ago

The answer already answers this question. Loop through the GridView and insert rows from there, not an uninstantiated DataTable. Further than that, I think you may benefit to understand the differences between your source and destination. Go back to basics a little more.

Rahul Over a year ago

@user3106114, as said in my answer, loop through the grid and then just follow your code .. the same way you were inserting data before. see my edit.

user3106114 Over a year ago

sir but this line showing error "For Each gridviewrow gr In gv.Rows" syntax error

Rahul Over a year ago

it's DataGridViewRow and not gridviewrow. so change that line to For Each DataGridViewRow gr In gv.Rows. Please help yourself with further syntax errors.

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