Help - cant refresh rows in datagridview!

Help - cant refresh rows in datagridview!

• Ben821217

  Hmm it still doesnt work, I think the problem is I cannot seem to access the instance of the original form correctly. I can see all the properties of the first form, but even if I try clsoe the first form from the second, it still stays open....
  

• Paul Monaghan

  I had a similar problem in a web application because I was refreshing the dataview when in fact I needed to call a DataBind on the SQL datasource the grid was bound to for it's data.
  
  

• Poolius

  OK the key here is to providing the child form with a reference to the first. The code example here simply uses a button to initate the call to the second form but this is in essence what you double click on the datagrid would be doing something similar.

  This shows a new property called baseform on the form2 which you can set when you instantiate the instance of the form. The tableadapter fill method is moved into a public method that I can then call from form2 because I now have a reference - so when I click on the button on form2 it will save the record to the database, call the PopulateDataset method on form1 and close the form.

  This shows a general principle but the concept is passing the reference of the base form to the child form - so you can call parent form methods or modify properties from the child.

  Public Class Form1

  ''' <summary>
  ''' Populate the Dataset
  ''' </summary>
  ''' <remarks></remarks>
  Sub PopulateDataset()
  '//Call your fill Code to populate the dataset here/.
  Me.Table1TableAdapter.Fill(Me.TestDataSet.Table1)
  End Sub

  ''' <summary>
  ''' Call the Populate dataset on loading form
  ''' </summary>
  ''' <param name="sender"></param>
  ''' <param name="e"></param>
  ''' <remarks></remarks>
  Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
  PopulateDataset()
  End Sub

  ''' <summary>
  ''' Create a Child Form and ensure baseform property is set
  ''' </summary>
  ''' <param name="sender"></param>
  ''' <param name="e"></param>
  ''' <remarks></remarks>
  Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
  Dim x As New Form2
  x.BaseForm = Me '//Pass a reference from base form to Details form
  x.Show()
  End Sub

  
  Private Sub Table1BindingNavigatorSaveItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Table1BindingNavigatorSaveItem.Click
  Me.Validate()
  Me.Table1BindingSource.EndEdit()
  Me.Table1TableAdapter.Update(Me.TestDataSet.Table1)
  End Sub

  End Class

  Public Class Form2
  Dim _baseform As Form1

  
  ''' <summary>
  ''' A reference variable to the base form
  ''' </summary>
  ''' <value></value>
  ''' <returns></returns>
  ''' <remarks></remarks>
  Public Property BaseForm() As Form1
  Get
  Return Form1
  End Get
  Set(ByVal value As Form1)
  _baseform = value
  End Set
  End Property

  Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
  '//Whatever database Save Code you have the database
  _baseform.TestDataSet.Table1.Rows(0).Item(0) = 99
  _baseform.Table1TableAdapter.Update(_baseform.TestDataSet)

  '//Can call method PopulateDataset in Form1 to repopulate
  '//the form1 dataset when you click the close button to close the form
  _baseform.PopulateDataset()
  Me.Close()
  End Sub

  End Class

  
  

• J. Clark

  Hi,

  Thanks for the reply. Unfortunately this isnt working for me, ive managed to set the reference to the baseform ok however when I try and call my populate dataset code from within the child form I get the following error:

   

  System.NullReferenceException was unhandled
    Message="Object reference not set to an instance of an object."
   

  Any ideas what could be causing this

   

  EDIT - THIS IS NOW WORKING OK Didnt set the baseform property properly. Thankyou!

  
  
• Help - cant refresh rows in datagridview!