Streamline Filter By Character Sort ~ LEARN MS-ACCESS TIPS AND TRICKS

Streamlining Form Module Code in Standalone Class Module.

Data Filter by Character and Sort on Form.

Version 1.0 of this Article was originally published in April 2009 and introduces a significant change in the Demo Application Version 2.0. In this version, the Event Subroutines are executed from the standalone class module, rather than from the form module.

After realizing the advantages of Event Procedures Coding in Standalone Class Modules, I found it difficult to revert to the traditional, less organized, and time-consuming Form/Report Module VBA Coding procedures.

In traditional coding, modifying the code of a specific event subroutine in a Form Module—especially when dealing with multiple types of controls—usually involves several manual steps.

Open the Form in Design View.
Select the required Control.
Display its Property Sheet.
Select the specific Event Property.
Click on the Build Button to open the Event Procedure.
Write/Modify the Code.
Save the Form with the Code.
Open the Form in Normal View to test the change.

Typically, it takes about eight steps to reach a specific event procedure in the Form Module to write, edit, and save changes. While it’s true that multiple event procedures can be modified once the form is open, steps 2 through 6 must still be repeated for each individual event procedure. This repetitive process is both tedious and time-consuming, especially when performed numerous times during development. At the same time, designing the user interface also consumes significant effort, as both activities often occur in parallel. Furthermore, any code written directly in the Form Module remains locked there and cannot be reused elsewhere, except for public functions written in a Standard Module.

If you’re a beginner VBA programmer, learning the language alongside user interface design is best accomplished through the traditional method. If you’re an experienced developer, I encourage you to experiment with streamlined VBA event procedure coding in Standalone Class Modules and see firsthand how it compares to the traditional coding style.

This approach can offer valuable insights and significantly boost coding efficiency, saving substantial project development time. Moreover, the reusable VBA code in Standalone Class Modules can be easily exported and integrated into other projects, further enhancing productivity.

Streamlined event procedure coding involves more than just moving the code from the form module to the standalone class module. It's about organizing the event procedure code in a structured and concise manner, which promotes reusability without the need for duplicating code for multiple objects of the same type in the form module. This approach enhances code maintainability and reduces redundancy, resulting in a more efficient and manageable codebase.

Direct access to the Structured Event Subroutines in the Standalone Class Module eliminates the need for struggling with the form design view to reach a particular event subroutine. This direct access streamlines the development process, making it easier to locate and modify event procedures without the hassle of navigating through the form's design view.

Example of Structured Event Subroutine Coding:

The BeforeUpdate Event Procedure Code of several TextBoxes can be written within a single BeforeUpdate() Event Subroutine.

Private Sub txt_BeforeUpdate(Cancel As Integer)

'When the BeforeUpdate Event is captured the txt object will have
'the Name of the Object fired the Event
Select Case txt.Name

Case "Quantity"
    'Code
  
  Case "UnitPrice"
    'Code
  
  Case "SaleTax"
    ' Code
  
  Case . . .
  
End Select
End Sub

The seventh episode in this series of articles is a prime example of event subroutine code Reuse and illustrates an organized, structured approach to event procedure coding. By writing just one set of GotFocus and LostFocus Event Subroutines, you can efficiently manage the behavior of 25 or more text boxes on the form when they gain or lose focus. This example offers a straightforward demonstration of how to effectively implement the concept of streamlined event procedure coding in a standalone class module, emphasizing code reusability and reduced redundancy.

Microsoft Access controls, such as TextBoxes, Command Buttons, and others, rely on event-defining, event-firing, and event-capturing mechanisms, which form the foundation of streamlined event subroutine coding. I explored these concepts in detail during my presentation to the Access User Groups (Europe) on January 3, 2024. The presentation is available as a YouTube video on the Access User Groups (Europe) channel, titled Streamlined Event Procedure Coding in Standalone Class Modules, offering valuable insights into this coding approach.

In our current project of 'Filter by Character and Sort', the Customers Form’s record source is derived from the CustomersQ query, which contains multiple records. To enhance user experience and efficiency, we’ll implement a technique that swiftly filters records by allowing users to type the first one or more characters from the customer’s selected Data Field. Utilizing the form’s filter settings, matching records will be quickly identified based on the characters typed into a text box control. This feature will streamline the process of locating specific customer records, improving overall usability.

The Customers Form Image-1 Normal Data View.

Right-click to open Large Image in New Tab/Window.

Customers Form Image-2 with Filtered Data.

Right-click to open Large Image in New Tab/Window.

The yellow-highlighted TextBox serves as the filter input control. Above it, a ComboBox lets users select the field to search—in this case, the Last Name field. As text is entered into the filter box, the system matches the beginning of the selected field’s value and filters the records accordingly. This setup enables quick and efficient record searches based on starting characters, making it easier to locate specific names that meet the criteria.

In this example, three records are initially filtered, each with a Last Name beginning with the letter G. When you type ‘r’ after ‘G’ in the yellow-highlighted filter box, the first record (which contains ‘Go…’) no longer matches and is removed from the results. This dynamic filtering approach provides precise and efficient record retrieval, updating in real time as users type, and making it easier to quickly locate records that meet the search criteria.

Right-click to open Large Image in New Tab/Window.

When the Backspace key is pressed to remove the last character from the filter TextBox, the data instantly updates to reflect the new filtering criteria based on the remaining characters. If no characters remain, the filter is cleared and the full dataset is displayed in the form’s detail section. This ensures a seamless, real-time filtering experience that intuitively responds to user input.

The Cls_ObjInit Class Module VBA Code.

Option Compare Database
Option Explicit

Private WithEvents frm As Access.Form
Private WithEvents txt As Access.TextBox
Private WithEvents cmd As Access.CommandButton
Private WithEvents cbo As Access.ComboBox

Dim txt2Filter

Public Property Get m_Frm() As Access.Form
    Set m_Frm = frm
End Property

Public Property Set m_Frm(ByRef vFrm As Access.Form)
    Set frm = vFrm
    
    Call Class_Init
End Property

Private Sub Class_Init()
Const EP = "[Event Procedure]"

Set txt = frm.FilterText
Set cmd = frm.cmdClose
Set cbo = frm.cboFields

With frm
    .OnLoad = EP
    .OnUnload = EP
End With

With txt
    .OnKeyUp = EP
End With

With cmd
    .OnClick = EP
End With

With cbo
    .OnClick = EP
End With

End Sub

Private Sub cbo_Click()
    frm.FilterText = ""
    txt2Filter = ""
    frm.Filter = ""
    frm.FilterText.SetFocus
    frm.FilterOn = False
End Sub

Private Sub txt_KeyUp(KeyCode As Integer, Shift As Integer)
Dim C As Integer, sort As String
Dim L As String

On Error GoTo txt_KeyUp_Err
C = KeyCode

With frm
Select Case C
    Case 8 'backspace key
        txt2Filter = Nz(![FilterText], "")
        If Len(txt2Filter) = 1 Or Len(txt2Filter) = 0 Then
            txt2Filter = ""
            .FilterOn = False ' remove filter
            frm.Recalc
            
        Else
            txt2Filter = Left(txt2Filter, Len(txt2Filter) - 1) 'delete the last character
            If Len(txt2Filter) = 0 Then
                .FilterOn = False ' remove filter
                
            Else 'set filter and enable
                .Filter = "[" & ![cboFields] & "]" & " like '" & txt2Filter & "*'"
                ![FilterText] = txt2Filter
                
                'position cursor position at the end of the text
                If Len(!FilterText) > 0 Then
                    .Section(acFooter).SetTabOrder
                    ![FilterText].SelLength = Len(![FilterText])
                    SendKeys "{END}" 'position cursor at right end of text
                End If
                
                .FilterOn = True
            End If
        End If
       
    Case 37 'right arrow key, prevent text highlighting
        SendKeys "{END}" 'position cursor at right end of text
    
    Case 32, 48 To 57, 65 To 90, 97 To 122 'space, 0 to 9, A to Z, a to z keys
        txt2Filter = txt2Filter & Chr$(C)
        
        'First letter of words to uppercase
        ![FilterText] = StrConv(txt2Filter, vbProperCase)
        SendKeys "{END}"
        GoSub SetFilter
End Select
End With

txt_KeyUp_Exit:
Exit Sub

SetFilter:
With frm
  .Refresh
  If Len(txt2Filter) = 0 Then
        .FilterOn = False ' remove filter
  Else 'set filter and enable
        .Filter = "[" & ![cboFields] & "]" & " like '" & txt2Filter & "*'"
        .FilterOn = True
  
  ' Set sort order
        sort = IIf(!Frame10 = 1, "ASC", "DESC")
        .OrderBy = "[" & !cboFields & "] " & sort
        .OrderByOn = True
  
        .Section(acFooter).SetTabOrder 'Form Footer Section Active
  'position cursor at end of text
        ![FilterText].SelLength = Len(![FilterText])
        SendKeys "{END}"
  End If
End With
Return

txt_KeyUp_Err:
MsgBox Err.Description, , "txt_KeyUp()"
Resume txt_KeyUp_Exit
End Sub

Private Sub cmd_Click()
    DoCmd.Close acForm, frm.Name
End Sub

There are three controls in the footer of the form, each triggering simple events that run corresponding code—except for the TextBox, which handles a more complex KeyUp() event.

In this scenario, creating separate Wrapper Class Objects is unnecessary for the TextBox, ComboBox, and Command Button, since only one instance of each exists on the form.

Within the Cls_ObjInit class module, the main object instances are declared in the global section using the WithEvents keyword, enabling Event capture and execution of their respective subroutines. Additionally, a Variant-type variable, txt2Filter, is declared globally, followed by the Form Property procedures.

The Class_Init() subroutine is then called from the Set m_Frm() property procedure after receiving the form object from the Form_Load() event procedure in the form module.

Next, the txt, cmd, and cbo objects are assigned references to their respective controls on the form and enabled with the required events.

The ComboBox Click event selects a field name to serve as the Filter target. This action resets any previously applied filter.
The Command Button Click event closes the form.
The TextBox KeyUp event captures valid keystrokes, builds the input string character by character, and applies it dynamically as a filter against the field selected in the ComboBox.

The txt_KeyUp() Event Subroutine Code.

Private Sub txt_KeyUp(KeyCode As Integer, Shift As Integer)
Dim C As Integer, sort As String
Dim L As String

On Error GoTo txt_KeyUp_Err
C = KeyCode

With frm
Select Case C
    Case 8 'backspace key
        txt2Filter = Nz(![FilterText], "")
        If Len(txt2Filter) = 1 Or Len(txt2Filter) = 0 Then
            txt2Filter = ""
            .FilterOn = False ' remove filter
            frm.Recalc
            
        Else
            txt2Filter = Left(txt2Filter, Len(txt2Filter) - 1) 'delete the last character
            If Len(txt2Filter) = 0 Then
                .FilterOn = False ' remove filter
                
            Else 'set filter and enable
                .Filter = "[" & ![cboFields] & "]" & " like '" & txt2Filter & "*'"
                ![FilterText] = txt2Filter
                
                'position cursor position at the end of the text
                If Len(!FilterText) > 0 Then
                    .Section(acFooter).SetTabOrder
                    ![FilterText].SelLength = Len(![FilterText])
                    SendKeys "{END}" 'position cursor at right end of text
                End If
                
                .FilterOn = True
            End If
        End If
       
    Case 37 'right arrow key, prevent text highlighting
        SendKeys "{END}" 'position cursor at right end of text
    
    Case 32, 48 To 57, 65 To 90, 97 To 122 'space, 0 to 9, A to Z, a to z keys
        txt2Filter = txt2Filter & Chr$(C)
        
        'First letter of words to uppercase
        ![FilterText] = StrConv(txt2Filter, vbProperCase)
        SendKeys "{END}"
        GoSub SetFilter
End Select
End With

txt_KeyUp_Exit:
Exit Sub

SetFilter:
With frm
  .Refresh
  If Len(txt2Filter) = 0 Then
        .FilterOn = False ' remove filter
  Else 'set filter and enable
        .Filter = "[" & ![cboFields] & "]" & " like '" & txt2Filter & "*'"
        .FilterOn = True
  
  ' Set sort order
        sort = IIf(!Frame10 = 1, "ASC", "DESC")
        .OrderBy = "[" & !cboFields & "] " & sort
        .OrderByOn = True
  
        .Section(acFooter).SetTabOrder 'Form Footer Section Active
  'position cursor at end of text
        ![FilterText].SelLength = Len(![FilterText])
        SendKeys "{END}"
  End If
End With
Return

txt_KeyUp_Err:
MsgBox Err.Description, , "txt_KeyUp()"
Resume txt_KeyUp_Exit
End Sub

The Sub KeyUp() Event Subroutine takes only the Key Code from the Keys 0-9, A-Z, and a-z. The Backspace key removes the last character entered into the Filter Text input Textbox. Right-arrow character Code is also valid, which moves the I bar to the END of the Filter text and prevents highlighting the full text when the Input text box is refreshed.

The Backspace keypress will truncate the right-most character from the Filter input Text, and the Filter action is refreshed. When the Filter input control is empty, the data filter is reset, and full data is displayed on the Form.

The Form Module Code.

Option Compare Database
Option Explicit

'Global declaration
Private obj As New Cls_ObjInit

Private Sub Form_load()
    Set obj.m_Frm = Me
    Application.SetOption "Behavior Entering Field", 2
End Sub

Private Sub Form_Unload(Cancel As Integer)
    Application.SetOption "Behavior Entering Field", 0
    Set obj = Nothing
End Sub

Filter By Character in ComboBox Items.

Right-click to open Large Image in New Tab/Window.

The screenshot above shows the second form, Customers_Combo, which demonstrates the Filter by Character feature applied to ComboBox items. The KeyUp() event subroutine is almost identical to the filter method used in the first form we reviewed earlier.

For this form, a new class module named Cbo_ObjInit has been introduced. The VBA code for the Cbo_ObjInit class module is provided below:

Option Compare Database
Option Explicit

Private WithEvents frm As Access.Form
Private WithEvents txt As Access.TextBox
Private WithEvents cmd As Access.CommandButton
Private cbo As Access.ComboBox

Dim txt2Filter

Public Property Get m_Frm() As Access.Form
    Set m_Frm = frm
End Property

Public Property Set m_Frm(ByRef vFrm As Access.Form)
    Set frm = vFrm
    
    Call Class_Init
End Property

Private Sub Class_Init()
Const EP = "[Event Procedure]"

Set txt = frm.FilterText
Set cmd = frm.cmdExit
Set cbo = frm.cboCust

With frm
    .OnLoad = EP
    .OnUnload = EP
End With

With txt
    .OnKeyUp = EP
End With

With cmd
    .OnClick = EP
End With


End Sub

Private Sub txt_KeyUp(KeyCode As Integer, Shift As Integer)
Dim i As Integer
Dim SQL As String
Dim SQL1 As String
Dim SQL2 As String


On Error GoTo txtKeyUp_Err
SQL = "SELECT CustomersQ.* FROM CustomersQ ORDER BY CustomersQ.[Last Name];"

SQL1 = "SELECT CustomersQ.* FROM CustomersQ "
SQL2 = "WHERE (((CustomersQ.[Last Name]) Like '" '"Gr*"));

i = KeyCode

Select Case i
    Case 8 'backspace key
        frm.Refresh
        If Len(txt2Filter) = 1 Or Len(txt2Filter) = 0 Then
            txt2Filter = ""
        Else
            txt2Filter = Left(txt2Filter, Len(txt2Filter) - 1) 'delete the last character
        End If
        GoSub SetFilter
    Case 37 'right arrow keys
        SendKeys "{END}"
    Case 32, 48 To 57, 65 To 90, 97 To 122 'space, 0 to 9, A to Z, a to z keys
        txt2Filter = txt2Filter & Chr$(i)
        frm![FilterText] = StrConv(txt2Filter, vbProperCase)
        GoSub SetFilter
End Select

txtKeyUp_Exit:
Exit Sub

SetFilter:
  If Len(Nz(txt2Filter, "")) = 0 Then
    With frm
        .cboCust.RowSource = SQL
        .cboCust.Requery
        .cboCust.SetFocus
        .cboCust.Dropdown
    End With
  Else 'set filter and enable
        SQL = SQL1 & SQL2 & txt2Filter & "*'));"
    With frm
        .cboCust.RowSource = SQL
        .cboCust.Requery
        .cboCust.SetFocus
        .cboCust.Dropdown
    End With
  End If
Return

txtKeyUp_Err:
MsgBox Err.Description, , "txtKeyUp()"
Resume txtKeyUp_Exit
End Sub

Private Sub cmd_Click()
    DoCmd.Close acForm, frm.Name
End Sub

In the earlier approach, we applied the Form Filter method, where the characters entered into a TextBox served as filter criteria to restrict the records displayed in the form’s record source.

In contrast, the ComboBox method dynamically builds an SQL statement using the filter text entered into a TextBox. This SQL is then assigned to the Row Source of the ComboBox, refreshing its contents in real time based on the updated criteria.