Reading the Text property of a combobox by reference

Reading the Text property of a combobox by reference

• AdriaanDavel

  How about the following.

  If TypeOf cbxModel Is ComboBox Then

  'Cast to combox box as early as possible and use combo box properties, SelectedText, SelectedItem etc.

  ' Change all combo box objects to reference to 'current' object

  Dim current As ComboBox = CType(cbxModel, ComboBox)

  If current.SelectedText <> Nothing And _

  cbxModel.Text <> " " Then

  '' Create duplicate of the generic control cbxModel

  '' as a true ComboBox to use ComboBox properties

  Dim cbxModel2 As ComboBox = CType(cbxModel, ComboBox)

  Me.OdbcDAAccess.SelectCommand.CommandText = AddWhereClause(Me.OdbcDAAccess.SelectCommand.CommandText, _

  cbxModel2.DataSource.ToString, _

  "Not using Combobox obj and members as above" cbxModel.Text)

  '' Model for AddWhereClause call, using an actual combobox on form

  '' Me.OdbcDAAccess.SelectCommand.CommandText = AddWhereClause(Me.OdbcDAAccess.SelectCommand.CommandText, "prodid", Me.cbxProdID.Text)

  End If

  End If

  
  

• Thelostcircuit

  Sounds like broken databinding to me... There's probably something wrong with the way you've bound your controls and/or data sources...

  The SelectedText property will typically return String.Empty in databound scenarios, but the SelectedValue, SelectedItem, and Text properties should all return the appropriate underlying value.

  For instance, create a simple example: One DataSet with one DataTable. A BindingSource whose DataSource is set to the DataSet and the DataMember is set to the DataTable. Use one ComboBox whose DataSource is the BindingSource, DisplayMember is a Field in the DataTable and ValueMember is a Field in the DataTable. Add three Labels, one for the Text property, one for the SelectedValue, and one for any other field in the DataTable that is not already being used for Display or Value Memebers. Add a Button. Then use code similar to the following:

  Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
  
  For Each c As Control In Me.Panel1.Controls
  
  If c.GetType Is GetType(ComboBox) Then
  
  Dim cbx As ComboBox = CType(c, ComboBox)

  Me.Label1.Text = cbx.Text
  Me.Label2.Text = cbx.SelectedValue

  Dim drv As DataRowView = CType(cbx.SelectedItem, DataRowView)
  Me.Label3.Text = drv.Row.Item("Some Column Name")
  
  End If
  
  Next
  
  End Sub

  You'll find that all three labels display the expected values. You issue must stem from something deeper than what you've shown.

  
  
  

• Ajaykr

  "Use one ComboBox whose DataSource is the BindingSource..."

  That may be the problem. I'm not using a BindingSource at all. As a throw-back to VS2k3 style, my datasource is the dataset itself for all my comboboxes; no middleman BindingSources live in my code. I've heard that this keeps your resulting executable lighter in weight since databinding is done at execution time rather than predefined in the mix. Still, I've never needed actual data from the controls until now.

  Any comments I've give the BindingSource routine a try in the meantime. Thanks, rkimble!

  
  
  

• Khookie

  Why not do something similar to the following

  
  Dim cbx As ComboBox

  For Each c As Control In Me.Panel1.Controls
  If TypeOf (c) Is ComboBox Then
  cbx = c

  If cbx.SelectedText.Length > 0 Then
  Me.OdbcDAAccess.SelectCommand.CommandText = AddWhereClause(Me.OdbcDAAccess.SelectCommand.CommandText, cbx.Name, cbx.DataSource.ToString, cbx.Text)
  '' Model for AddWhereClause call, using an actual combobox on form
  '' Me.OdbcDAAccess.SelectCommand.CommandText = AddWhereClause(Me.OdbcDAAccess.SelectCommand.CommandText, "prodid", Me.cbxProdID.Text)
  End If
  End If
  Next

  
  

  This looping construct iterates through the panel1 controls collection and processes only combobox within this collection. Then all you need to do is use the properties of the cbx variable in the IF construct

  
  

• Steven Syfuhs

  Nice try, guys, but I think you're both missing the point here. Everything else, being Name, DataSource, even DataTable if I needed it, casts (or transfers) from the generic Control (NewControl, c) to the specific ComboBox (cbxModel, cbx) except the current state of the value properties SelectedText and Text. In fact, nothing having to do with the value state of the combobox is cast, including SelectedIndex, SelectedItem and SelectedValue.
  
  
• Reading the Text property of a combobox by reference