Question

Brief : I have code which works if I don’t dispose of the BindingSource after it has been assigned to DataGridView.DataSource but breaks if I do dispose it – why? Do I need to worry about disposing this?

Public Sub GridViewUpdate()
        Dim cn As New System.Data.SqlServerCe.SqlCeConnection
        Dim SQL As System.Data.SqlServerCe.SqlCeCommand
        Dim tbl As New DataTable
        Dim adp As System.Data.SqlServerCe.SqlCeDataAdapter
        Dim Bds As New BindingSource

        DataGridView1.Columns.Clear()

        cn.ConnectionString = "Data Source = C:\path\data.sdf"
        SQL = cn.CreateCommand
        SQL.CommandText = "SELECT myfields FROM myTable  ORDER BY field1 DESC, field2 ASC"
        cn.Open()
        adp = New SqlServerCe.SqlCeDataAdapter(SQL)
        adp.Fill(tbl)
        Bds.DataSource = tbl

        DataGridView1.DataSource = Bds

        cn.Close()
        cn.Dispose()
        SQL.Dispose()
        adp.Dispose()
        tbl.Dispose()
        Bds.Dispose()   '*** <<--- This breaks it - GridView becomes empty

End Sub

So, what is going on here? When I set DataGridView1.DataSource = Bds does it just do this as a reference? How does Bds get disposed once the procedure exits? Does garbage collection pick it up if I assign something else to DataGridView1.DataSource? Do I need to worry about this?

Answer 1

Ah, got it!

DataGridView1.DataSource = Bds.DataSource

I guess using = Bds just creates a reference but = Bds.DataSource does not.

Disposing the BindingSource does not cause problems this way.