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How To Display Boolean Values in Bound DataGrid


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This article was previously published under Q191717

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Summary

An empty binary field formatted with rules to print text, such as "Yes" for True and "No" for False, will return an error unless nulls are allowed.

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More information

Steps to Reproduce Behavior

  1. Create a new standard EXE project in Visual Basic. Form1 is created by default.
  2. In the project, reference Microsoft ActiveX Data Objects 2.0 Library and Microsoft Data Formatting Object Library.
  3. Add a DataGrid to the form.
  4. Add the following code and run:
          Option Explicit
    
          Private rs As ADODB.Recordset
          Private fmtBooleanData As StdDataFormat
    
          Private Sub Form_Load()
          Dim i As Integer
    
          Set rs = New ADODB.Recordset
          rs.Fields.Append "Field1", adBSTR, 64
          rs.Fields.Append "BooleanField", adBoolean
          rs.Open
    
          rs.AddNew
          rs.Fields("Field1").Value = "Field1"
          rs.Fields("BooleanField").Value = True
          rs.Update
    
          For i = 1 To 5
             rs.AddNew
             rs.Update
          Next i
          rs.MoveFirst
    
          Set DataGrid1.DataSource = rs
    
          ' set up Boolean Formatting
          Set fmtBooleanData = New StdDataFormat
          fmtBooleanData.Type = fmtBoolean
          fmtBooleanData.TrueValue = "Yes"
          fmtBooleanData.FalseValue = "No"
          fmtBooleanData.NullValue = ""
    
          Set DataGrid1.Columns(1).DataFormat = fmtBooleanData
    
          End Sub
    
    					
When the code is run, you will see "Yes" in the 2nd column of the first row, and #ERROR in the rest.

This occurs because OLE DB cannot determine what to return for an empty non-nullable field, and therefore raises an error. Marking the field as nullable by changing the line:
   rs.Fields.Append "BooleanField", adBoolean
				

to:
   rs.Fields.Append "BooleanField", adBoolean, , adFldIsNullable
				

will result in the empty fields returned as NULLs rather than errors.

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Keywords: KB191717, kbhowto, kbdatabase, kbctrl

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Article Info
Article ID : 191717
Revision : 5
Created on : 7/1/2004
Published on : 7/1/2004
Exists online : False
Views : 489