NullReferenceException on DataGridView.Columns Index property

Collapse
This topic is closed.
X
X
Collapse
 
  • Page of 1
  • Time
  • Show
Clear All
new posts
Previous template Next
  • Kathy
    #1

    NullReferenceException on DataGridView.Columns Index property

    I am trying to set a tooltip for a column cell in a data grid as
    documented in the MS Visual Studio 2005 documentation. I set up a test
    to match the example exactly including database column, data grid
    column and data values. I also have a tooltip control on the form. If
    I comment out the 'if' test, it works fine, but uncommented, I get a
    NullReferenceEx ception error on the
    Me.dataGridView 1.Columns("Rati ng").Index reference. Here is the code
    snippet from the help doc:

    ' Sets the ToolTip text for cells in the Rating column.
    Sub dataGridView1_C ellFormatting(B yVal sender As Object, _
    ByVal e As DataGridViewCel lFormattingEven tArgs) _
    Handles dataGridView1.C ellFormatting

    If e.ColumnIndex = Me.dataGridView 1.Columns("Rati ng").Index _
    AndAlso Not (e.Value Is Nothing) Then

    With Me.dataGridView 1.Rows(e.RowInd ex).Cells(e.Col umnIndex)

    If e.Value.Equals( "*") Then
    .ToolTipText = "very bad"
    ElseIf e.Value.Equals( "**") Then
    .ToolTipText = "bad"
    ElseIf e.Value.Equals( "***") Then
    .ToolTipText = "good"
    ElseIf e.Value.Equals( "****") Then
    .ToolTipText = "very good"
    End If

    End With

    End If

    End Sub 'dataGridView1_ CellFormatting


    I'm new to vb.net, so be kind :-)

    Thanks for the help.

    Tags: None
    • rowe_newsgroups
      #2
      Re: NullReferenceEx ception on DataGridView.Co lumns Index property

      Well, lets check the simple cause first. Does the column named "Rating"
      exist when this code executes?

      Thanks,

      Seth Rowe

      Kathy wrote:
      I am trying to set a tooltip for a column cell in a data grid as
      documented in the MS Visual Studio 2005 documentation. I set up a test
      to match the example exactly including database column, data grid
      column and data values. I also have a tooltip control on the form. If
      I comment out the 'if' test, it works fine, but uncommented, I get a
      NullReferenceEx ception error on the
      Me.dataGridView 1.Columns("Rati ng").Index reference. Here is the code
      snippet from the help doc:
      >
      ' Sets the ToolTip text for cells in the Rating column.
      Sub dataGridView1_C ellFormatting(B yVal sender As Object, _
      ByVal e As DataGridViewCel lFormattingEven tArgs) _
      Handles dataGridView1.C ellFormatting
      >
      If e.ColumnIndex = Me.dataGridView 1.Columns("Rati ng").Index _
      AndAlso Not (e.Value Is Nothing) Then
      >
      With Me.dataGridView 1.Rows(e.RowInd ex).Cells(e.Col umnIndex)
      >
      If e.Value.Equals( "*") Then
      .ToolTipText = "very bad"
      ElseIf e.Value.Equals( "**") Then
      .ToolTipText = "bad"
      ElseIf e.Value.Equals( "***") Then
      .ToolTipText = "good"
      ElseIf e.Value.Equals( "****") Then
      .ToolTipText = "very good"
      End If
      >
      End With
      >
      End If
      >
      End Sub 'dataGridView1_ CellFormatting
      >
      >
      I'm new to vb.net, so be kind :-)
      >
      Thanks for the help.

        Comment

        • Kathy
          #3
          Re: NullReferenceEx ception on DataGridView.Co lumns Index property


          rowe_newsgroups wrote:
          Well, lets check the simple cause first. Does the column named "Rating"
          exist when this code executes?
          >
          Thanks,
          >
          Seth Rowe
          >
          Yes it does. It is visible in the column properties within the
          datagridview.

            Comment

            • rowe_newsgroups
              #4
              Re: NullReferenceEx ception on DataGridView.Co lumns Index property

              Are you adding the Rating Column with code or by using the "Add Column"
              dialog in design view? Also what are you putting in for the Name
              property and the Header Text property of the column? I used the
              following in my form_load event to add the "Rating" column and
              everything works fine.

              DataGridView1.C olumns.Add("Rat ing", "Rating")
              Dim values() As String = {"*", "**", "***", "****"}
              For i As Integer = 0 To 4
              DataGridView1.R ows.Add(values( i))
              Next i

              Let me know what you find out.

              Thanks,

              Seth Rowe


              Kathy wrote:
              rowe_newsgroups wrote:
              Well, lets check the simple cause first. Does the column named "Rating"
              exist when this code executes?

              Thanks,

              Seth Rowe
              >
              Yes it does. It is visible in the column properties within the
              datagridview.

                Comment

                • Kathy
                  #5
                  Re: NullReferenceEx ception on DataGridView.Co lumns Index property


                  rowe_newsgroups wrote:
                  Are you adding the Rating Column with code or by using the "Add Column"
                  dialog in design view? Also what are you putting in for the Name
                  property and the Header Text property of the column? I used the
                  following in my form_load event to add the "Rating" column and
                  everything works fine.
                  >
                  DataGridView1.C olumns.Add("Rat ing", "Rating")
                  Dim values() As String = {"*", "**", "***", "****"}
                  For i As Integer = 0 To 4
                  DataGridView1.R ows.Add(values( i))
                  Next i
                  >
                  Let me know what you find out.
                  >
                  Thanks,
                  >
                  Seth Rowe
                  >
                  >
                  I did not add the column in code. If I go into Edit Columns now,
                  Rating is one of the columns in the list. AND its properties shows
                  Rating as the DataPropertyNam e as well as the HeaderText.

                  Thanks,
                  Kathy

                    Comment

                    • Kathy
                      #6
                      Re: NullReferenceEx ception on DataGridView.Co lumns Index property

                      I got it working by changing the following:

                      If e.ColumnIndex = Me.dataGridView 1.Columns("Rati ng").Index _

                      to:

                      Dim col as New DataGridViewCol umn

                      col = Me.dataGridView 1.Columns(e.Col umnIndex)

                      if col.DataPropert yName = "Rating" _


                      I guess Microsoft needs to correct their documentation ;)

                      Kathy

                        Comment

                        Previous template Next
                        Working...