Learn Microsoft Access Advanced Programming Techniques, Tips and Tricks.

Creating Access Menu with Tree View Control

The Microsoft Access Project Menu, when finished with the Tree View Control, will look like the Image given below.

The Image above shows the Report Group’s third Option Custom Report is selected and highlighted, with the Report Filter Parameter Form open, overlapping the Menu Screen, for User’s input.

Before going into that, in last Week’s Lesson we have learned how to organize the related items in hierarchical order, using Microsoft Tree View Control, based on the Sample  data Table. 

I have made a point last week, that the related items in Tree View control’s data need not necessarily be next to each other.  After this you will be more clear about as how to update Relative Keys of Child Nodes, irrespective of it’s physical position of the records in the Table, but based on the relationship with it’s Parent Node IDs. 

This was the Data Table that we have used and finished with last week’s exercise:

Can you add the following list of items at the end of the above table and update their ParentID field values so that the TreeView display look like the sample image given below:

New records for Table item record related field:

  1. Text Field.
  2. Number Field.
  3. Date/Time Field.
  4. Hypelink Field.

Form related Controls:

  1. Text Box.
  2. Command Buttons.
  3. Combo Box.
  4. List Box.

Report related Controls:

  1. Text Box.
  2. Label.
  3. Graph Chart.

Assign ParentID Values to these items so that the Tree View Display looks like the following Image:

Now, we will proceed with the creation of an MS-Access Project Menu and learn what it takes to create one. A simple Menu Image is given below:


It is a simple Menu with only three group of options: Forms, Report Views and Macros. 

Under Forms Group two options are given, the first one displays the Tree View controls Menu table record.  The second Option displays the same records in continuous form mode.

The first option under Report View displays a Report on products Category records, from the Categories Table of NorthWind.accdb database.

The second option displays the Products List-Price Report.

The third option opens a Parameter Form so that the User can set the Minimum and Maximum List-Price values range, to Filter data for the Products List-Price Report.

Under the Macros Processes Group both option runs Macro1 and Macro2 respectively and displays different messages.

We need a Menu Table with the above option records with some additional fields, besides the usual TreeView’s Unique IDs, Description and ParentID data fields.  The Menu Table Image is given below:

Create a Table with the above structure and add the above records and save it with the name MenuID field is AutoNumber, PID and Type fields are Numeric fields, others are Text Fields.

We are familiar with the first three Data Fields: the Unique ID, Description and the ParentID Fields. Here, I have shortened the ParentID field name to PID.

We need four more fields in the Menu Table, one field Type for the object type Code and three fields Form, Report and Macro.

Type Field contains the Access Object Type Numeric Codes to identify the Option the User clicked on.

  • Form field is for Form Names, object Type code 1,
  • Report Field contains Report Names, object Type code 2,
  • Macro Field is for Macro Names, object type code 3.

Note: All the object names can be put in one Column. We have used separate fields for clarity only.  If you do that then make changes in the VBA Code, wherever it references different field names.

Based on the code numbers we can pickup the Object Names, from their respective fields and call the DoCmd.Openform or Docmd.OpenReport or Docmd.RunMacro to execute the action on the Child Node Clicks.

Now, the only question remains is how to link/store these two information (the Type Code and Object Name) on the Child Nodes?  We will take up that topic when we start Adding the Nodes to the Tree View control.

We need two more data Tables for sample Forms and Reports.  The Categories Table and Products Tables, from the NorthWind.accdb sample Database.  To save your time I have attached the Demo Database with all the Objects and Programs at the end of this Page to Download and try it out.

Create two Forms using the Menu Table with the names Data Entry and another Form Data View in continuous Form mode.

Create two Reports, one on the Categories Table with the report name: Categories,  another report on Products Table with the name Products Listing.  Add a long Label control below the main heading on the Products Listing Report and change the Name Property Value to Range.

Create a small form with two unboound Text Boxes and change their name Property Value to Min & Max, like the design given below:

Add two Command Buttons as shown above.  Change the Caption Property Value of the first Button to Open Report and the Name Property Value to cmdReport.

Change the Second Command Button’s Caption to Cancel and the Name Property value to cmdCancel.

Display the Code Module of the Form.  Copy and Paste the following Code into the Form Module and save the Form:

Private Sub cmdOpen_Click()
Dim mn, mx, fltr As String
mn = Nz(Me![Min], 0)
mx = Nz(Me![Max], 9999)
If (mn + mx) > 0 Then
    fltr = "[List Price] > " & mn & " And " & "[List Price] <= " & mx
    DoCmd.OpenReport "Products Listing", acViewReport, , fltr, , fltr
Else
    DoCmd.OpenReport "Products Listing", acViewReport
End If

End Sub

Private Sub cmdCancel_Click()
DoCmd.Close
End Sub

When the User sets a Value Range by entering the Minimum and Maximum List Price range in their respective Text Boxes the Report Filter criteria String is created.  The Report Filter String value is passed to the Product Listing Report as Open Report command Parameter.  The Filter String value is also passed as OpenArgs (Open Argument) Parameter. 

The Filter parameter filters the Report Data, based on the Criteria, specified in Min & Max fields, and the open argument value is copied to the Range Label Caption when the Report is open.

Copy and Paste the following Code into the Product Listing Report’s VBA Module:

Private Sub Report_Open(Cancel As Integer)
    DoCmd.Close acForm, "Parameter"
    Me.Range.Caption = Nz(Me.OpenArgs, "")
End Sub
  1. Create a new Form, with the name frmMenu and add the Microsoft TreeView Control from the Activex Control’s List.  Resize the Control as shown in the Design View below:
  2. Change the Tree View Control’s name to TreeView0 in the normal Property Sheet.
  3. Add a Command Button below the Tree View control.  Change it’s Name Property Value to cmdExit and Caption Property value to Exit.
  4. Right-Click on the Tree View Control and highlight the TreeCtrl_Object option and select Properties to display the Property Sheet.
  5. Change the following Property Values as given below:
  • Style = 7 (tvwTreeLinesPlusMinusPictureText)
  • Line Style = 1 (tvwRootLines)
  • LabelEdit = 1 (tvwManual)

Last Week we have changed the first two Property Values.  When LabelEdit Property’s default value is 0 -  tvwAutomatic, Clicking on the Node twice (not double-click) the Node-Text will go on Edit Mode and you can change the Text.  But it will not directly update on the data source field.  By changing it to 1 – tvwManual will prevent it from going into edit mode.

We can change this through Code by adding the following lines in the Form_Load() Event Procedure:

With Me.TreeView0.Object
    .Style = tvwTreelinesPlusMinusPictureText
    .LineStyle = tvwRootLines	
    .LabelEdit = tvwManual
End With

Last Week we have used the Form_Load() Event Procedure to read the Tree View Node values to create the Root-level and Child Nodes.  We need the same Procedure here also with few lines of  additional Code.

Besides that we need to trap the Node_Click() Event of Nodes to check which Option the User has selected.

Copy and Paste the following VBA Code into the Form Module and Save the Form.

Option Compare Database Option Explicit Dim tv As MSComctlLib.TreeView Const KeyPrfx As String = "X" Private Sub Form_Load() Dim db As Database Dim rst As Recordset Dim nodKey As String Dim PKey As String Dim strText As String Dim strSQL As String Dim tmpNod As MSComctlLib.Node Dim Typ As Variant Set tv = Me.TreeView0.Object tv.Nodes.Clear

‘Change the TreeView Control Properties

With tv
    .Style = tvwTreelinesPlusMinusPictureText
    .LineStyle = tvwRootLines
    .LabelEdit = tvwManual
    .Font.Name = "Verdana"
End With

strSQL = "SELECT ID, Desc, PID, Type,Macro,Form,Report FROM Menu;" Set db = CurrentDb Set rst = db.OpenRecordset(strSQL, dbOpenDynaset) Do While Not rst.EOF And Not rst.BOF If Nz(rst!PID, "") = "" Then nodKey = KeyPrfx & CStr(rst!ID) strText = rst!Desc Set tmpNod = tv.Nodes.Add(, , nodKey, strText) 'Root-Level Node Description in Bold letters With tmpNod .Bold = True End With Else PKey = KeyPrfx & CStr(rst!PID) nodKey = KeyPrfx & CStr(rst!ID) strText = rst!Desc Set tmpNod = tv.Nodes.Add(PKey, tvwChild, nodKey, strText) 'Check for the presense of Type Code If Nz(rst!Type, 0) > 0 Then Typ = rst!Type Select Case Typ Case 1 'save type Code & Form Name in Node Tag Property tmpNod.Tag = Typ & rst!Form Case 2 'save type Code & Report Name in Node Tag Property tmpNod.Tag = Typ & rst!Report Case 3 'save type Code & Macro Name in Node Tag Property tmpNod.Tag = Typ & rst!Macro End Select End If End If rst.MoveNext Loop rst.Close Set rst = Nothing Set db = Nothing End Sub Private Sub cmdExit_Click() If MsgBox("Close Menu Form? ", vbYesNo, "cmdExit_Click()") = vbYes Then DoCmd.Close End If End Sub Private Sub TreeView0_NodeClick(ByVal Node As Object) Dim varTag, typeid As Integer Dim objName As String, nodOn as MSComctlLib.Node If Node.Expanded = False Then Node.Expanded = True Else Node.Expanded = False End If

‘Reset the earlier lighlight to normal

For Each nodOn In tv.Nodes
    nodOn.BackColor = vbWhite
    nodOn.ForeColor = vbBlack
Next

‘changes BackColor to light Blue and ForeColor White

tv.Nodes.Item(Node.Key).BackColor = RGB(0, 143, 255)
tv.Nodes.Item(Node.Key).ForeColor = vbWhite

‘—Highlight code ends-

varTag = Nz(Node.Tag, "") If Len(varTag) > 0 Then typeid = Val(varTag) objName = Mid(varTag, 2) End If Select Case typeid Case 1 DoCmd.OpenForm objName, acNormal Case 2 DoCmd.OpenReport objName, acViewPreview Case 3 DoCmd.RunMacro objName End Select End Sub

On the Global Declaration Area of the Module the Tree View Object is declared.  A constant variable KeyPrfx is declared with the value “X”.

The Form_Load() Event Procedure of last week’s Article we have modified with additional Code.  I have commented the new Code segment to give an indication of what it does but will explain what it does.

The Procedure declares Database, Recordset and four String Variables.  Next two line declares a temporary Node Object: tmpNod and Typ Variant Variables are declared.

Next, the TreeView Object tv is assigned with the TreeView0 Object on the Form.  The TreeView0’s existing Nodes, if any, are cleared with the statement: tv.Nodes.Clear, in preparation for loading all the Nodes again.

We have implemented the following Code to modify the Tree View control’s Properties through Code, rather than through the Property Sheet.

With tv
    .Style = tvwTreelinesPlusMinusPictureText
    .LineStyle = tvwRootLines
    .LabelEdit = tvwManual
    .Font.Name = "Verdana"
End With 

The Tree View Font is changed to Verdana. Besides that we will bring in some more functions like expand or collapse all the Menu Groups with one click, rather than manually expanding or collapsing one group after the other.

The new SQL String is modified to add the new Fields Type, Form, Report and Macro Fields from Menu Table.

The Menu Table’s first record is checked for the presense of any value in PID field, if it is empty then it is a Root-level Node record. It is added to the Tree View Object as the Root level Node and it’s reference is saved in the tmpNod Object.

The Node have several properties like Forecolor, Bold and several others out of that we have taken the Bold Property and assigned True to make the Root level Node look different than it’s Child Nodes.

If it is not Root Node entry then it has the PID value, the program takes the Else clause and the record is added as a Child Node.  Here, we checks the Type field value.  If it contains one of the three values 1, 2 or 3 then we must take the value from Form, Report or Macro Name along with that the Type Code and join them together  (like ”1Data Entry”, “2Category Listing” etc.) and save it in the Tag Property of Child Nodes.  We are familiar with the Tag Property in Access controls, like Text Boxes, Labels, Command Buttons and others, but we rarely use it.

The cmdExit_Click() Procedure closes the Menu Form, if the response from the User is affirmative.

When the User clicks on a Child Node, the value we have saved in it’s Tag Property must be extracted and checked to determine what to do next.  For this we need a TreeView0_NodeClick() Event Procedure.

Private Sub TreeView0_NodeClick(ByVal Node As Object) Dim varTag, typeid As Integer Dim objName As String, nodOn as MSComctlLib.Node If Node.Expanded = False Then Node.Expanded = True Else Node.Expanded = False End If

‘Reset the earlier lighlight to normal

For Each nodOn In tv.Nodes nodOn.BackColor = vbWhite nodOn.ForeColor = vbBlack Next nodOn

‘changes BackColor to light Blue and ForeColor White tv.Nodes.Item(Node.Key).BackColor = RGB(0, 143, 255) tv.Nodes.Item(Node.Key).ForeColor = vbWhite ‘—Highlight code ends- varTag = Nz(Node.Tag, "") If Len(varTag) > 0 Then typeid = Val(varTag) objName = Mid(varTag, 2) End If Select Case typeid Case 1 DoCmd.OpenForm objName, acNormal Case 2 DoCmd.OpenReport objName, acViewPreview Case 3 DoCmd.RunMacro objName End Select End Sub

The Click() Event Procedure receives the clicked Node’s Reference as Parameter in the object Node.  At the beginning of this procedure we have declared few Variables.

Next few lines checks whether the clicked Node is in expanded or collapsed state.

Normally, to expand a Node, to show it’s hidden child Nodes, either we click on the + (plus symbol) at the left side of a Node or double-click on the Node itself.  Double-Clicking on the Node again or clicking on the – (minus symbol) will hide the Child Nodes.

With the following Code segment we can expand or collapse Child-Nodes with a single Click:

If Node.Expanded = False Then
    Node.Expanded = True
Else
    Node.Expanded = False
End If 

The next six executable lines ensures that the Node received the Click remains highlighted.

‘Reset the earlier Highlight to Normal

For Each nodOn In tv.Nodes nodOn.BackColor = vbWhite nodOn.ForeColor = vbBlack Next nodOn

‘Changes BackColor to light Blue and ForeColor White tv.Nodes.Item(Node.Key).BackColor = RGB(0, 143, 255) tv.Nodes.Item(Node.Key).ForeColor = vbWhite ‘—Highlight code ends-

Next, the Tag Property value is read into the varTag Variable. If it is not empty then the value is split into two part. The Numeric value is extracted and saved in Typid variable and the Object Name part is saved in variable objName.

Depending on the value in Typid variable the Docmd is executed to open the Form, Report or Runs the Macro.

We will add two more Command Buttons on the Top of the Menu. One to expand all the Nodes with one Click and the second one to collapse all the Nodes.

  1. Add two more Command Buttons at the top area of the Tree View Control as shown on the design below.
  2. Change the Name Property Value of the left Command Button to cmdExpand and the Caption to Expand All.
  3. Similarly, change the right-side Command Button’s Name Property to cmdCollapse and the Caption to Collapse All.
  4. Copy and Paste the following VBA Code below the existing Code in the frmMenu Form Module and save the Form.
Private Sub cmdExpand_Click()
Dim Nodexp As MSComctlLib.Node

For Each Nodexp In tv.Nodes
    If Nodexp.Expanded = False Then
        Nodexp.Expanded = True
    End If
Next Nodexp
End Sub


Private Sub cmdCollapse_Click()
Dim Nodexp As MSComctlLib.Node

For Each Nodexp In tv.Nodes
    If Nodexp.Expanded = True Then
        Nodexp.Expanded = False
    End If
Next Nodexp
End Sub

At the beginning of the cmdExpand_Click() Event we have declared a Tree View Node object NodExp.  The For . . . Next loop takes one Node at a time and checks whether it is in expanded form or not.  If not then it’s Expanded Property value is set to True.

Similarly the cmdCollapse_Click() Event makes a similar check and if it is in expanded state then the Expanded Property value is set to False.

The full Tree View Control’s all Nodes can be expanded and makes all their child Nodes visible at once or all Child Nodes kept hidden except the Root-level Nodes.

Hope you enjoyed creating the new Menu for your Project.  If you run along the design task step by step then your Menu should look like the finished Menu Image given at the top.

During the Year 2007 I have designed a Menu in one of my Projects, for Vehicles Service Contract System, using the Tab Control with several Pages. Each Page having 10 or more Options and to make each Page appear in turn at the same area, when the User Clicks on the Command Buttons lined up at either side of the Menu. Command Buttons at the right-side also changes, based on the selection of left side Button.

Click to Enlarge

You can find the Menu Design with Tab Control Article on this Link:https://www.msaccesstips.com/2007/06/control-screen-menu-design.html


CLASS MODULE

  1. MS-Access Class Module and VBA
  2. MS-Access VBA Class Object and Arrays
  3. MS-Access Base Class and Derived Objects
  4. VBA-Base Class and Derived Object-2
  5. Base Class and Derived Object Variants
  6. MS-Access Recordset and Class Module
  7. Access Class Module and Wrapper Classes
  8. Wrapper Class Functionality
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Microsoft TreeView Control Tutorial

A. Introduction.

Microsoft Tree View Control is part of Microsoft Windows Common Controls. It is an interesting piece of Object that displays related data in an hierarchy of Nodes.  It can display related data, like entries and sub-entries in an Index List or listing of folders like Windows Explorer’s Left-Pane or a List of related Items in an hierarchical structure with Tree-Lines, Check-Boxes and Graphics of bitmap Images.

The ListView and ImageList Controls are part of Windows Common Controls and we will be using them along with the TreeView Control in Microsoft Access. 

I think you would like to look at some sample TreeView Control Demo Images, which we will be working on to build in the coming few weeks.

B. Sample Demo Images.

  1. The Sample Demo TreeView Image with all Nodes in Collapsed form.
  2. The above TreeView Control Nodes in expanded view.
  3. TreeView Sample Display, with arrow-head Image Icons displayed to the left of each Node Text.
  4. Next, the TreeView Display with linked data in a Sub-Form.  Root level Nodes have two Images.  Folder-Closed Image is displayed in normal mode.  When the Root Level Node receives a Mouse Click it displays the Folder-Open image and displays the Child-Nodes in expanded form. 

    Related information is displayed on the Sub-Form based on selection of Root level Node.

    One of the Child-Node item selected it displays another Form (normally kept hidden) with related information.

  5. On the next Form Image there are two Panels. The Product Category Item related Nodes are in TreeView Control, in the left Panel.  When one of the Category item receives a Click on the TreeView control, related Product Items with Quantity and List Price in separate Columns will appear in ListView Control, in the right-side Panel.

C. Creating Sample Data for Trial Run.

Let us try out the TreeView Control with some sample data shown below, based on the first two images shown at the beginning of this Page.

The above sample data table have three Fields. 

  • The ID field is an AutoNumber field with Unique ID Numbers.  The AutoNumber type is selected for our convenience.  In either case All records in the Table should have a Unique ID Value.  If it is Numeric then it should be converted into String Type, before adding it to the TreeView Control.
  • Second field is Node Description (Desc). The rows of information on this Column are  logically related. 
  • The third ParentID field is Numeric Type, to match the type of ID Field.  But it should be converted to String Type before using it on TreeView Control.

We must know how the Description Column values are related each other, based on that we can establish the relationship by entering related values into the ParentID field.

For example: The logical arrangement of relationship between Author of Books, Publishers of the Books,  the Book Stores where the Books are on Sale etc. or like Relationship between members iof a Family Tree. 

Relationship between Product Category, Products, Stock, Price and so on. All these information may not appear under one Column in a single Table.  They may appear in different Columns or in different tables as well.

The ParentID field is very important that it determines the hierarchical arrangement of Nodes. If the ParentID Field is empty then that record should go as a Root-level Node.  The Child-Node always should have their ParentID filled in with it’s Parent records ID Value.

Root level Node can have one or more Child Node(s), Child Node can have it’s own child Node(s).

We will load the above data into a TreeView Control and see how it looks.  Then we will fill up the ParentId field with related IDs to change the view, the way we want to see it in a logical order.

D. Windows Common Controls Library file.

  1. But, first thing first, open one of your Database or create a new one.
  2. Open the VBA Window (ALT+F11) and select References… from Tools Menu.
  3. Look for the File: Microsoft Windows Common Controls in the displayed list of files and put check-mark to select it.

    If you could not find the file in the list, Click Browse... Button and find the file: MSCOMLIB.OCX in the Windows System directory, for Windows 7 Version look for the file in SysWOW64 folder.  Click OK to close the Library Files listing Control.

  4. Create a Table with the following structure:
  5. Save the Table with the name Sample.
  6. Fill the Table with the sample data of 12 records as shown on the data view Image above.


    E. Creating TreeView Control on Form

  7. Create a New blank Form.
  8. Click on Activex Controls button from the Controls Group, find the Microsoft TreeView Control and select it.
  9. Click OK to insert a TreeView control on the Form.
  10. Drag the control down and to the right to leave some space at the top and left of the TreeView Control.  Drag the bottom right corner sizing handle towards the right and bottom corner to make the control larger, like the sample image given below.
  11. Display the Property Sheet of the control and change it’s Name Property Value to TreeView0, if it is different there.
  12. Display VBA Editing Window of the Form.
  13. F. Access VBA Code.

  14. Copy and Paste the following VBA Code into the Module overwriting the existing lines of Code there:

    Option Compare Database Option Explicit Dim tv As MSComctlLib.TreeView Const KeyPrfx As String = "X" Private Sub Form_Load() Dim db As Database Dim rst As Recordset

    Dim strSQL As String Dim nodKey As String Dim ParentKey As String Dim strText As String Set tv = Me.TreeView0.Object strSQL = "SELECT ID, Desc, ParentID FROM Sample;" Set db = CurrentDb Set rst = db.OpenRecordset(strSQL, dbOpenDynaset) Do While Not rst.EOF And Not rst.BOF If Nz(rst!ParentID, "") = "" Then nodKey = KeyPrfx & CStr(rst!ID) strText = rst!Desc

    ‘Add the TreeView Root Level Nodes tv.Nodes.Add , , nodKey, strText Else ParentKey = KeyPrfx & CStr(rst!ParentID) nodKey = KeyPrfx & CStr(rst!ID) strText = rst!Desc

    ‘Add the Record as Child Node tv.Nodes.Add ParentKey, tvwChild, nodKey, strText End If rst.MoveNext Loop rst.Close Set rst = Nothing Set db = Nothing End Sub

  15. Save the Form with the name frmSample, but don’t close the VBA Window.

    G. VBA Code Line-by-Line.

Let us take a quick look at the VBA Code and understand what it does.

In the Global Declaration Area, of the Form Module, the Variable tv declared as TreeView Object.  The KeyPrfx declared as Constant , with String Type value “X”. 

The TreeView Node’s Key Value must be always of String Type and needs at least one non-numeric character present in the Node Key.  Our sample Table Key Values are all in numeric form, we can convert and add it to the Constant value “X”.  Numeric Value converted into String Type alone will not accept as Node-Key.

Note: If the Node-Key and Parent-Key  values are already in Alpha or Alpha-Numeric form then the question of conversion doesn’t arise.  All Node-Key values must be Unique.

In the Form_Load() Event Procedure the Database and Recordset objects are declared.  Four String Variables are also declared.

The statement Set tv = Me.TreeView0.Object statement assigns, the TreeView0  Object on the Form, to the object variable tv.

The OpenRecordset() statement opens the Sample Table Records using the SQL strSQL.

The Do While… statement ensures that the recordset is not empty, if empty then exit the Loop and end the Program.

If there are records then the first record’s ParentId field is checked for the presense of some value in there or not.

If it is empty then that record is for TreeView control’s Root level Node item.  The Root level Node needs only the unique Node-Key Value, which we already have in the ID Field, and Item Description Field value for Text Argument.

If the ParentID field have some value then the record is a Child-Node (Child of Root level Node or child of some upper-level Child Node) of the TreeView Object. 

The next line creates the Key Argument Value in nodKey String Variable, with the ID field Value,  converted into String and added to the constant prefix X, Node-Key becomes X1.

The rst!Desc field value added to the String Variable strText, simply for clarity and to make it short in the Nodes.Add() method’s Parameter listing, if the field reference is very lengthy then this will keep the Add() method neat and tidy.

The next executable line: tv.Node.Add() calls the Add() method of TreeView.Nodes Object to add the Node to TreeView0 control on the Form frmSample

The Syntax of Add() method is given below for reference:

tv.Nodes.Add([Relative],[Relationship],[Key],[Text],[Image],[SelectedImage]) As Node

All six Parameters of Add() method are optional.  If you call this method without any parameters then an Empty Root level Node will be added and a blank tree-line will appear as an indicator in the TreeView control.

For TreeView Root Level Node requires the Key and Text Argument values.

For Child Nodes both [Relative] and [Relationship] Arguments are required. Omitting any one of them will insert the Node as a Root Node, but will not generate any error.

[Relative] is the NodKey of an existing Node, entered into the related record’s ParentID field.  [Relationship] is a Constant tvwChild with numeric value 4, identifying it as a Child Node of Key Value in ParentID Field.

The other Constant values for Relationship Argument are used for positioning Child Nodes in a specific location.  The Constant Values are as follows :

tvwFirst = 0,  places as first Node, at the level of the relative Node.

tvwLast = 1,  places as last Node, at the level of the relative Node.

tvwNext = 2,  places the Node after a specified Node.

tvwPrevious = 3, placess the Node immediately preceeding the specified Node.

Note: You may experiment by setting  each Value in the Relationship Argument and Run the Code in Debug Mode, after keeping the VBA Window and Form in Normal View side by side. Watch how the Nodes are getting arranged in each cycle of the code execution to understand. 

These will be useful while editing the TreeView Control by Deleting an Item and inserting another item in it’s place or add a new Node at a specific location.

A Node with [Relative] Key must exist in the Nodes Collection before attempting to add a Child-Node to that Node, otherwise the Add() method generates an error.

This process is repeated till all the records are processed in the recordset.

Note: You may review the VBA Code again after the Demo Runs.

H. The First Trial Run.

Open the Form in Normal View.  The Trial Run result will look like the Image given below.

It doesn’t look more than a normal Listbox.  Remember we have not filled-in any value in the ParentID field in our Sample Table.  We have to establish some relationship between the Items in the rows of Record to move and position them in an hierarchical order in the TreeView Control.

I. Understanding the Relationship between Records.

  1. Open the Sample Table and let us examine the Records and how they are related.
  2. Let us leave the Database item alone as a Root Item.

    The Database Object also have some top-level objects: Application, DBEngine, Workspaces Collection and Databases Collection, which we have omitted here.

  3. Then we have the Tables group Item with ID value 2.
  4. Next Table, Fields and Field items are related to the Tables group.  We want Table, Fields and Field items to line up under the parent Item Tables Group Record with ID value 2.
  5. Let us call the record Tables as the Parent Node, Table, Fields and Field records as Child-Nodes.

    J. Updating the ParentID Field.

  6. So we need to update the value 2 (Node-Key of Tables) in ParentID field of Table, Fields and Field  records.
  7. Please update only those records and close the Table.  When it is done the records will look like the Image given below:
  8. Now, open the your frmSample in Form View and check the TreeView Control.  The result will look like the earlier one without any change.  The changes are already happened but it is not visible to you.

    K. The Property Sheet of TreeView Control.

  9. The TreeView Control has it’s own Property Sheet and the settings in there influences it's appearance.  So we will make a change in one of it’s Properties and come back to view the TreeView again.

  10. Turn the frmSample in Design View.
  11. Right-Click on the TreeView Control and high-light TreeCtrl_Object from the Shortcut Menu and select Properties.

    The Property Sheet will look like the Image given below:

  12. Settings on this Property Sheet changes the appearance of the TreeView Display.

    The left-side top Property Style is already set with the maximum features available Option-7 (tvwTreeLinesPlusMinusPictureText).

  13. Change the LineStyle Property Value = 1 (tvwRootLines) and Click Apply button then click OK to close the Property Sheet.

    L. Run After the LineStyle Property Value Change

  14. Save the Form and open it in Normal View.  Now, the Tree Lines are appearing correctly.  The Tables Node have a plus (+) sign at the left side, indicating that this Node have one or more Child Nodes in the next level and they are not in expanded form.
  15. Click on the plus symbol to expand the Node and display the Child Nodes, with the same ParentID.  When you click on the Minus Symbol the Child Nodes are collapsed and hidden, changing the symbold to plus sign again.
  16. The display will look like the following Image, when expanded:


    M. ParentID Updating of Other Records.

    We will update the Forms record ID Value (Node-Key Value) into Form, Controls and Control records’ ParentID fields, so that these records will list under the Forms Node as it’s Child Nodes.

    Similarly update ParentID field of Report and Controls records with Reports ID (Node-Key Value) Value  so that Report and Controls items will position under the Parent Node Reports, as it’s Child Nodes.

  17. Make changes to your Sample table records with the ParentID values as shown below:

    After the above changes the TreeView Display will look like the following Image, when all the Nodes are in expanded form.

    All Child Nodes related to the Root level Nodes: Tables, Forms and Reports are grouped as a list under their Parent Nodes.  But a Child Node may have a Parent Node, Grand-Parent Node or a Great Grand-Parent Node.

    N. Arranging All Object in Logical Hierarchical Order.

    For example let us take the first Root level Node Tables.  Logically Field (with record ID 5) is directly related to the Fields collection (record ID 4), the Fields collection related to Table and Table is part of Tables collection.  Each item in the group (record number 5 to 2) is related to one step up to the next level.

    So let us position these Child Nodes correctly under their own Parent Node and see how it looks.

  18. Open your Sample Table and change the ParentID values of the Tables related Child Records as shown below:

  19. The Field with ID-5 record’s Parent is Fields, record with ID-4, hence we have updated the 5th record’s ParentID field with ID Number 4.
  20. Like wise 4th record’s ParentID field updated with 3 and 3rd Record’s ParentID is updated with record number 2.

    Note: Don't assume that the items arranged in this way must be next to each other.

  21. After changes to the records save the Table and Open the frmSample to view the changes.  Your TreeView display should look like the image given below, with all Nodes in expanded form.

The Child-Node of a Root level Node can be a Parent-Node to it’s own Child or Children.  This way it can go several step down the tree.

Change the other two group of Child Node's ParentID field values to look like the Image given above.


DICTIONARY OBJECT

  1. Dictionary Objects Basics
  2. Dictionary Object Basics-2
  3. Sorting Dictionary Object Keys and Items
  4. Display Records from Dictionary
  5. Add Class Objects as Dictionary Items
  6. Update Class Object Dictionary Item
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MS-Access Class-Module Tutorial Index

We are planning a Series of Tutorials on Microsoft Windows Tree View Control Programming in Microsoft Access and will publish the Series in the coming weeks.

In the meantime I thought it is appropriate to organize the earlier Tutorial Links, on Class Module and Event Handling Programming Series, of Articles on a separate page, for easy access in  published order.

This is helpful for those who would like to go through the Tutorials on a gradual progressive way of learning. Those tutorials were started from the Basic-level and progressed through the more advanced stage of programming levels. The learning curve should start from the base level and go up to the top to understand the changes at each level. Once you are familiar with the Object or Control, you may continue to learn further by experimenting with them  on your own Programs or Projects.

After all, there are more than one way to solve a problem in Computer Programming, based on the Programer’s own understanding of the Language, Skill and Experience.  

We have developed an Android App ('Microsoft Access Guru' - MSA Guru in short) and is available in Google Play Store to Download and Install it on your Android Phone. This App connects directly to the website:www.msaccesstips.com and you may select the Articles, from it’s Menu/Sitemap, the interested Topic you are looking for.

You may Download and Install the App from Google Play Store so that you can pick the group of required Articles Organized in the Sitemap Page to Read/Learn Access VBA Programming.

CLASS MODULE TUTORIALS

  1. MS-Access Class Module and VBA
  2. MS-Access VBA Class Object and Arrays
  3. MS-Access Base Class and Derived Objects
  4. VBA-Base Class and Derived Object-2
  5. Base Class and Derived Object Variants
  6. MS-Access Recordset and Class Module
  7. Access Class Module and Wrapper Classes
  8. Wrapper Class Functionality

COLLECTION OBJECT

  1. MS-Access and Collection Object Basics
  2. MS-Access Class Module and Collection Objects
  3. Table Records in Collection Object

DICTIONARY OBJECT

  1. Dictionary Objects Basics
  2. Dictionary Object Basics-2
  3. Sorting Dictionary Object Keys and Items
  4. Display Records from Dictionary
  5. Add Class Objects as Dictionary Items
  6. Update Class Object Dictionary Item

MS-ACCESS EVENT HANDLING TUTORIALS

  1. Withevents MS-Access Class Module
  2. Withevents and Defining Your Own Events
  3. Withevents Combo List Textbox Tab
  4. Access Form Control Arrays And Event
  5. Access Form Control Arrays And Event-2
  6. Access Form Control Arrays And Event-3
  7. Withevents in Class Module for Sub-Form
  8. Withevents in Class Module and Data
  9. Withevents and Access Report Event Sink
  10. Withevents and Report Line Hiding
  11. Withevents and Report-line Highlighting
  12. Withevents Texbox and Command Button
  13. Withevents Textbox Command Button
  14. Withevents and All Form Control Types


Download Android App MSA Guru Version of LEARN MS-ACCESS TIPS AND TRICKS from Google Play Store.

Download Link: MSA Guru  Size: 2.3MB
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MS-Access Tips on your Finger-Tip

  • Download Android App 'MSA Guru' Version of LEARN MS-ACCESS TIPS AND TRICKS from Google Play Store.

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