Programming Access Option Groups with VBA

In my previous post on How to Use Option Buttons, we learnt how to set up an Option Button Group bound to a field in the form's underlying database table.  We learnt that an Option Button Group is comprised of two separate types of control - the Option Group control itself, and the individual Option Buttons within it. Once set up, these function together as a single unit.  

Today we are going to learn how to set up a similar Option Button Group, but this time, we are going to use VBA to determine which button has been selected, and change the behaviour of the form based upon the selection. 

Screen Colour Option Group

To do this we are going to set up an Option Group containing three Option Buttons (see screenshot above).  When the user clicks one of the buttons in the Option Group,  VBA subprocedures are called, and the background colour of the form changes in accordance with the users' selection. Here is a video of how it works in practice.

The process for setting up the form with the Option Group is very similar to that which we went through in my last blog post on How to Use Option Buttons.  The main difference is that previously we bound the data selected in the Option Group to a field in the form's underlying database table.  This time, however, we are going to leave the Option Group unbound, and reference the data selected in the Option Group with VBA code.  To do this we will need to make use of the Option Groups On Click event to trigger the subprocedure containing that code when the user clicks any button in the Option Group.

Setting up the Form and Option Group

Here is the procedure for setting up the Option Group:

1) Create a new form by clicking the FORM DESIGN icon on the CREATE ribbon.
2) Go to the CONTROLS section of the DESIGN ribbon and drag an OPTION GROUP control down onto the design grid. 

3) Open the PROPERTY SHEET while the OPTION GROUP CONTROL is highlighted and enter the name "opGrp" in the NAME property (under the OTHER tab)

4) Next go back to the CONTROLS section and drag an OPTION BUTTON control onto the OPTION GROUP which we placed on the grid in the previous step.

5) Enter the name "optRed" in OPTION BUTTON's NAME property whilst the control is highlighted.

6) Repeat steps 4 and 5 twice, creating two more  OPTION BUTTONS called "optGreen" and "optBlue" respectively.

Design View of our Option Group containing the three Option Buttons - optRed, optGreen and optBlue

The next step in the process is to check the OPTION VALUE property is set up correctly for each of the buttons.  To do this you will need to select each Option Button in turn, and go to the property sheet DATA tab. The values are set automatically when you drag the Option Button controls into the Option Group, but just to be sure, check the value for optRed is "1", optGreen is "2" and optBlue is "3".

The Option Value property for optRed.

As you may recall from my last blog post, the Option Button selected by the user at runtime determines the Value of the Option Button Group as a whole. As such, if the user selects optGreen, the value of the group is "2" etc.  It is this value that our VBA code needs to reference when the subprocedure runs.

Programming the Option Group

Let us now turn our attention to the VBA code which executes when the user clicks one of the Option Buttons at runtime. In order for our code to detect when any button within the Option Button Group is selected, we need to make use of the Option Group's ON CLICK event.

This is done as follows:

1) Select the Option Group Control (which we have called "optGrp") on the design grid so it is highlighted orange.

2) Go to the PROPERTY SHEET and select the EVENTS tab.

3) Click the ellipse button ("...") at the end of the ON CLICK property row to open the VBA editor.

Selecting the ON CLICK event for the "optGrp" OPTION GROUP.  Clicking the 
ellipse button ("...") opens the VBA editor.

After clicking the ellipse button on the ON CLICK row of the PROPERTY SHEET, the VBA editor will have opened and automatically created a sub procedure called "optGrp_Click".  This is the ON CLICK event-handler. Any code we enter here will be executed when the user clicks any button in the option group at runtime. 

Our first programming task is to determine which Option Button the user clicked.  This is done by referencing the Option Groups VALUE property as follows:

formname!optiongroupname.Value

In our case the code will be:

Me!opGrp.Value

"Me" is a quick and simple way to reference the form name within which the code module is contained;  "opGrp" is the name of our Option Group; and Value is a reference to the value property of the Option Group as a whole.  Note the form name and control name is separated by the "!" character, and the control name and property is separated by a full stop ".". 

Referencing the OPTION GROUPS VALUE property in this way gives us the OPTION VALUE of the button selected by the user.  As you may recall the OPTION VALUE for the red button was "1", green was "2" and blue was "3".  So if the user clicked the green button, the above statement will return "2" when it executes at runtime.

In order to use the OPTION GROUPS VALUE property to change the background colour of the form, we are going to do two things. Firstly we are going to call a separate VBA sub procedure from the OPTION GROUPS ON CLICK event-handler, passing the VALUE property as the parameter; secondly, we are going to create this subprocedure which will process the VALUE property and then change the background colour of the form. 

The event-handler code is as follows:

Private Sub opGrp_Click()

    Call setBackgroundColour(Me!opGrp.Value)

End Sub

As we learnt above, the first and last line of this event handler is created automatically when we clicked the ellipse button ("...") in the ON CLICK row of the Option Groups property sheet.  All we have done is add the middle line to call a sub procedure called setBackgroundColour (yet to be created), and pass the referenced value of the Option Group as the parameter.

Let us take a look at the code for our setBackgroundColour sub procedure:

Private Sub setBackgroundColour(intOpValue)

    Dim lngRed As Long, lngGreen As Long, lngBlue As Long

    lngRed = RGB(255, 230, 230)

    lngGreen = RGB(242, 255, 230)

    lngBlue = RGB(230, 240, 255)

    

    Select Case intOpValue

    

        Case 1

            Me.Detail.BackColor = lngRed

            

        Case 2

            Me.Detail.BackColor = lngGreen

            

        Case 3

            Me.Detail.BackColor = lngBlue

            

    End Select

    

End Sub 

Here is a breakdown of how the code works: 

1) The first line of the sub procedure receives the option value argument (intOpValue) which was passed to it from the calling statement we wrote in the ON CLICK event handler.

2) The next section sets up three variables of the LONG data type and assigns each one a colour value which is used to set the forms BackColor property to red, green or blue as required.

3) Next we have set up a SELECT CASE statement to determine the value of the intOpValue variable which, as we have learnt above, contains the OPTION VALUE of the OPTION BUTTON clicked by the user at runtime.

4) Then each respective CASE statement tests whether it's value matches intOpValue.  When it comes to one that does, the BackColor property of form is set accordingly. So if the value of intOpValue is "2", the second Case statement invokes ...  Me.Detail.BackColor = lngGreen ... to set the form's background colour to green.

There is just one more thing we need to do before we can see our form and code in action. This involves calling the setBackgroundColour sub procedure as soon as the form has opened.  This is so the form's background colour is set in accordance with the default option button selection in the first instance.

To do this we are going to make use of the forms ON CURRENT event which fires just after the form opens.  The procedure is similar to how we set up the ON CLICK event-handler for the Option Group.  This time we need to select the form in the design grid by clicking the square at the top right and then open the property sheet for the FORM.

Selecting the FORM in design view.

 

Then we need to open the EVENT tab (of the FORMS property sheet) and click the ellipse ("...") button at the end of the ON CURRENT row.  This creates the event-handler in the VBA editor.  Once that has been created we just need to enter the same code as previously to call the setBackgroundColour sub procedure as follows:

Private Sub Form_Current()

    Call setBackgroundColour(Me!opGrp.Value)  

End Sub

That's it!  Our form with the programmed option group is now ready to open and use.

How to Use Option Buttons (aka Radio Buttons or Option Groups)

 What are Option Buttons?

So what are Option Buttons, and what are they used for? Option Buttons are a user-friendly form control that enables users to select a single value from a group of given options.  This is done by clicking one of a number of boxes, with each box representing one of the available options.  When the user clicks a box to select the value, any previously selected boxes are unselected as a result.  In this way, only one value can be selected at any one time.  

Example of an Option Button Group.

For example, in the screenshot above, there are three options for the user to select one out of a possible three teams - team 1, team 2 and team 3.  The advantage of using an option button group over a combo box with the same available list of values is that it is quick and simple for the user to enter data.  It is also preferable to a textbox in so far as it limits the value entered to one in the group of options.  On the downside, an option button group tends to take up more space of the form, particularly if there are many options to choose from.  If this is the case, a combo box with data entry restricted to items in the list, maybe a better choice.

In the following exercise, we are going to re-create the Option Button Group from the above screenshot.  To begin with, let take a look at the underlying database table.

The underlying database table containing the "team" field 
for the Option Group's Control Source.

As we can see, the underlying table contains four fields - ID, firstName, surname and team.  It is the latter field, team, which is going to be the Control Source for our Option Button Group. Before we start the exercise it is worth mentioning that the Option Button Group is actually comprised of two separate types of control: first, we have the Option Group control, and then we have the individual Option Button controls which are contained within the Option Group.  So to re-create the Option Button Group in the exercise below, we will need to use 1 Option Group control, and 3 Option Buttons, four separate controls acting together as one.  It is the Option Group control that contains the Control Source property for the group as a whole, whilst the Option Buttons each have their own individual Option Value properties.

How to Create an Option Button Group

1. Open the form in DESIGN VIEW.
2. Select the OPTION GROUP control from the  DESIGN RIBBON
   
   and drag it down onto the form design grid.
3. Whilst the OPTION GROUP control is still selected in the design grid, open or go to the PROPERTIES window, select the DATA tab, and then select team from the CONTROL SOURCE drop-down list (NB this assumes you have already set the CONTROL SOURCE of the form itself to the underlying table).

   

   Form design grid with the option group control 
   added (highlighted orange).  The property sheet is also visible
   for the control with team entered as the control source.

   
   
4. Next, select the OPTION BUTTON control from the DESIGN RIBBON, and drag it down onto the OPTION GROUP which you added to the design grid in step 2.  You should notice the OPTION GROUP turn black once the OPTION BUTTON is over the control and ready to drop.  This indicates that the button will be added to the group.
5. Whilst the OPTION BUTTON is still selected, open and/or go to the PROPERTY WINDOW, select the DATA TAB, and check the OPTION VALUE property.  It should say "1".  This is the value that will be bound to the team field if the button is selected by the user at runtime.
6. Repeat steps 4 and 5 for the remaining two CONTROL BUTTONS checking the OPTION VALUE properties say "2" and "3" respectively.

   
   

   Design grid showing three option buttons added to the
   option group control.  The property sheet for the third control button
   (showing the option value property) is also visible.

The form should now be ready to open in FORM VIEW.  The screenshot below shows the finished form with the underlying table.  I have added some data to demonstrate how information contained in the Option Button Group is stored in the database.

Form with option button group.  Select an option button on the form results in the option value property being stored in the underlying database table.

Note how team 3 is selected for the Sarah Arden record (ID 7) in the option button group.  As you may remember, the option value property was set to "3" for the last button.  This is the value that has been stored in the underlying database table.

This post has shown how we create an option button group using a combination of an option group control and three option buttons.  I have demonstrated how the control source for the group as a whole is bound to a field in the forms underlying database table, and how each option button has a unique option value property which is the value stored if the user selects a given button at runtime.  

In a future post, I intend to show how option button groups can be used to control the behaviour of a form at runtime, rather than being bound to a field in an underlying database table. To do this I will demonstrate how we can reference the option button group with VISUAL BASIC code, and respond to its click events.

Using Custom Functions in Calculated Controls

Back in May 2012, I wrote a blog article on Writing Custom Functions for Access VBA.  Custom functions work the same way as MS Access built-in functions such as DateAdd, DatePart and DSum, but are instead created ourselves as database developers.  We do this by creating a public function with the VBA programming language and save it inside a global module within the database.

The blog I wrote in 2012 explained how these custom functions can be accessed from sub procedures associated with forms and reports elsewhere in the database.  Today, however, I am going to explain how custom functions can be utilised in calculated form controls, without needing to invoke them with VBA itself.

Let's begin by looking at the custom function we are going to use.

Custom Function to get Week Commencing

I have created a custom function called getWeekCommencing to calculate the week commencing date of a given week, in a given year.  For example, the week commencing date of the 14th week of 2019 is 1st April 2019 (if we count Monday as the first day of the week). As such the function takes two arguments - week number and year.  The full syntax for using the function is as follows:

getWeekCommencing(weekNumber, Year)

The code I used to create this function is as follows:

Public Function getWeekCommencing(intWeekNo, intYear)
On Error GoTo myError
    Dim intJan1 As Integer
    Dim varStartDate As Variant  
    intJan1 = Weekday(DateSerial(intYear, 1, 1), vbMonday)
    varStartDate = DateAdd("d", -(intJan1 - 1), DateSerial(intYear, 1, 1))
    getWeekCommencing = DateAdd("ww", intWeekNo - 1, varStartDate)  
leave:
    Exit Function
myError:
    MsgBox Error$
    Resume leave  
End Function

If you are unfamiliar with VBA you can still copy this code into your database and use it within a calculated control. There are instructions for doing this below:

Instructions for adding the function to your database.

1.  Copy the code above onto your clipboard.
2.  Open the database you are going to add the function to.
3.  Select the CREATE ribbon.

   

   Above: The MODULE icon is located on the right-hand side of the CREATE ribbon.

   
   
4. Click the MODULE icon from the MACROS AND CODE group.  This opens the VBA editor and creates a new module ready for the code to be added:
5. Paste the code into the VBA editor as in the screenshot below:

Above: The VBA Editor:

You may notice that I have changed the default name of the Module (see the PROJECT EXPLORER in the 

left-hand side bar) from Module 3 to "myFunctions".  You can do the same by highlighting the module name in the 

project explorer and hitting the F4 button to bring up the PROPERTIES window. You may then change the name property

 to one of your choice.  However, this is not essential.

The custom function is now ready to use in a calculated form control. 

Setting up the Test Data for this Exercise

Before we create the form to test the function, we first need to set up a simple database table containing test data. The table needs just two fields: WeekOfYear and Year, both of which are of the NUMBER data type.

Above: tblWeeks in Design View

Above: tblWeeks in Form View with test data entered.

Once the table is set up, we can add our test data as I have done in the screenshot above. Although there are  52 week in the year, the first week may not start on a Monday, so the data entered in WeekOfYear field can be anything between 1 and 53 (so the possibility of a partial first week is offset by Week 53).

The Calculated Control

Now we have added the getWeekCommencing function along with test data to our database, we can create the form containing the calculated control.

Above: The Week Commencing Calculator form in Design View.

To do this we need to create a form bound to the tblWeeks table.  We then need to add three text boxes:  the first text box (txtWeekOfYear) is bound to the WeekOfYear field in tblWeeks, and the second (txtYear) is bound to the Year field.  The third text box (txtWeekCommencing) is unbound.  This is where we are going to add our calculated control which returns the week commencing date (based on the data displayed in the WeekOfYear and Year textboxes).

Here are the instructions for creating the calculated control:

1. Create the third text box that we are going to use for the calculated control as in the screenshot above. 
2. Display the PROPERTY SHEET if it is not already visibile.  The PROPERTY SHEET icon is located in the TOOLS group of the DESIGN ribbon.
3. Select the new text box by clicking on it.
4. Click the OTHER tab of the PROPERTY SHEET, and change the NAME property to txtWeekCommencing. (I also suggest you change the names of the first textbox to txtWeekOfYear and the second to txtYear by selecting them and changing the NAME properties).
5. Click the DATA tab on the PROPERTY SHEET (having first selected txtWeekCommencing).  We are now going to enter an expression which uses our getWeekCommencing custom function.  
6.  Enter the expression below directly into the CONTROL SOURCE property:

=getWeekCommencing([txtWeekNumber],[txtYear])

The txtWeekNumber parameter references the value in the txtWeekNumber textbox, and the txtYear parameter does the same for the txtYear text box.  

In this exercise, the expression was entered directly into the CONTROL SOURCE

property.  Alternatively, we could have clicked the elipse button at the end of the CONTROL SOURCE
property row to open the EXPRESSION BUILDER.  Using the Expresison Builder is, however, something 

I would need to cover another day, in another post!

And that's it! All you need to do now is save the form and open it in FORM VIEW.  Use the form's navigation buttons to view each record in the tblWeeks table.  The calculated control uses the getWeekCommencing custom function to processes the week number and year data for the current tblWeeks record, and displays the appropriate date.

NB - Just to clarify, the format for the week commencing date in this screenshot is for the UK (ie dd/mm/yyyy). 

The same date using the US format would be 01/07/2019 (mm/dd/yyyy). However, your computer should be set up
to display the date format appropriate for your location automatically.

Creating a Custom Save Button for an MS Access Form.

When we use an MS Access form to create a new record, or update one that already exists, the process of saving that data is normally taken care of automatically "behind the scenes."  All we need to do is move to or create a new record, close the form, or close the database, and Access saves the original record for us.

Record Navigation Buttons: when a record is added or changed, moving to a new or different record 

via the navigation buttons, will save the origin form record automatically.

However, there are times when it may necessary to save a record manually.  Suppose, for example, we have two tables joined together in a one to many relationship. We create a new record on a form bound to a table on the one side of the relationship, and then click a button to open a new form bound to a table on the many side of the relationship.  The newly opened form is then used to create a sub-record for the parent record on the original form.

Parent and sub-forms: In this screenshot, the parent form "Work Session" is bound to the tbl_work_session table, and the "Entry Log" form is bound to the tbl_entry_log table.  There is a one to many relationship between the two tables, with tbl_work_session being on the one side of the relationship.

The problem in this scenario is that when we come to close the form for the sub-record (thereby saving the data to the underlying table on the many side of the relationship), the parent record on the original form has not, at this stage, been inserted into the underlying table on the one side of the relationship.  That is to say, Access has not got around to autosaving the parent record since the parent form has not moved to any other record, or been closed etc - all we have done is click a command button to open a new form.  As such we get an error message saying "You cannot add or change a record because a related record is required in [the parent] table"; this is because the rules of referential integrity have been broken (ie the sub-record in the many table requires a parent record in the one table).

However, it is simple to overcome this issue. We just need to save the parent record manually before trying to close the sub-record form.  A quick and easy way to do this is to click the pencil symbol on the top left of the parent-form, or the SAVE icon in the RECORDS group of the HOME ribbon. This will save the parent record, thereby allowing it's sub-record to be saved afterwards.

 The pencil symbol (above left) can be used to save the current record manually.  Alternatively, the SAVE icon in the RECORDS group of the HOME ribbon (above right) can also be used.

However, this is not particularly useful from the perspective of user-friendliness. That is to say, a user may not realise or understand that this action is necessary.  A better way of doing it would be to save the parent record automatically when the user clicks the command button to open the sub record form. As such, we need to alter the open form button (referred to as "CREATE NEW ENTRY" in our example above) so it also becomes a custom save button.  To do this, we just add the following line of VBA code to the buttons ON CLICK event:

Application.RunCommand acCmdSaveRecord

See the screenshot below for the full code:

VBA code to save the parent record before opening the sub-record form.

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Creating a Custom Save Button from Scratch - A Tutorial

Here is a step by step tutorial for creating a custom save button from scratch on Access for Office 365:

1. Open the form in DESIGN VIEW.
2. Go to the CONTROLS group of the CREATE ribbon.
3. Click the MORE button () to the lower right of the control icons, and de-select the USE CONTROL WIZARDS icon when the additional options appear. 

   

   Above: additonal  options below control icons.

4. Click the BUTTON control icon () from the CONTROLS ribbon. The cursor will now change to a button icon when it enters the design grid.
5. Position the cursor at the desired location on the design grid, and click the left hand mouse button.  This will create the new button at the selected location.
6. Select the new BUTTON contol by left clicking it, and open the PROPERTIES sheet from the TOOLS group of the DESIGN ribbon (if it is not already open).
7. Click the EVENTS tab on the properties sheet, and left click the ON CLICK row of the events tab.
8. Click the ELIPSE button (three horizontal dots) which appears on the right hand side of the row.

   

   Above: the ON CLICK event row on the PROPERTIES sheet.

9. Select CODE BUILDER from the CHOOSE BUILDER dialog form which opens.  This opens the VBA editor.
10. Enter the following code in the CLICK sub procedure for the control button.

Above: The CLICK sub procedure for the new control button shown in the VBA editor.

Now when the user clicks the new button at runtime, any data s/he entered will be saved to the corresponding record in the forms underlying table.

Passing Multiple Values via the OpenArgs Parameter of DoCmd.OpenForm

The DoCmd.OpenForm command is a useful tool for the Access for Office 365 database developer wanting to control the manner in which a form opens during runtime.  I have written about it previously in my post on how to "Control Form Opening".  However, in today's post, we are going to focus on a specific area of this command's use - that is, how we can pass multiple values via its OpenArgs property.

The OpenArgs parameter of DoCmd.OpenForm gives us the means to pass a single string value to the OpenArgs property of new form being opened.  After the form has opened, this value can then be read and used by any code able to reference the new forms OpenArgs property. As things stand, the limitation of this is that we can only pass one string value as the command executes.  So let's see how we can get around this, and pass any number of strings values in one go.

To demonstrate how this works, I have created an Access for Office 365 form containing three text boxes and a submit button.  When the user populates the text boxes and clicks SUBMIT during runtime, the values contained in each of the three text boxes are passed over to a new form by means of the OpenArgs parameter of the DoCmd.OpenForm command.

Above: Form to pass multiple values via the OpenArgs parameter of DoCmd.OpenForm.

You can download the full OpenArgsPost.accdb database used in the this exercise from here. 

(NB I have tested the download process using the Chrome browser which works OK.  The download process may fail using other browsers such as Microsoft Edge. If you experience issues please try using a different browser). 

---

Part One: Passing the Values

Let's look at what happens behind the scenes when the SUBMIT button is clicked.  First of all, clicking SUBMIT (referred to as btnSubmit in DESIGN VIEW) results in the control button's ON CLICK event firing.  This, in turn, starts the following VBA event procedure (see screenshot below):

Above: The VBA event procedure for btnSubmit.

The code begins by declaring a string variable called strOpenArgs:

Dim strOpenArgs AS String

The next two lines of code reference the value entered by the user in the first text box.  The value is stored in the strOpenArgs string:

txtValue1.SetFocus
strOpenArgs = txtValue1.Text

The next two lines of code after that reference the value of the second text box, and append it to the strOpenArgs string preceded by a semi-colon (the significance of the semi-colon will be explained in part 3 of this post):

txtValue2.SetFocus
strOpenArgs = strOpenArgs + ";" + txtValue2.Text

This is then repeated for the third text box:

txtValue3.SetFocus
strOpenArgs = strOpenArgs + ";" + txtValue3.Text

So at this point in the program flow, the value of strOpenArgs is as follows:

"one;two;three"

This is the final value of the DoCmd.OpenForm OpenArgs parameter which will be passed to the new form in the following line of code:

DoCmd.OpenForm "frmReceiveOpenArgs", , , , , , strOpenArgs

---

Part Two: Retrieving the Values

Let's take a look at the new form which opens after the SUBMIT button has been clicked, and the event procedure explained above has finished executing:

Above: the new form which opens in response to clicking the SUBMIT button.

As you can see in the screenshot above, the new form consists of three empty text boxes (for displaying retrieved values) and a RETRIEVE button.  When the user clicks RETRIEVE the text boxes will be populated with the values submitted from the first form.  In our case, Retrieved Value 1 will display the value "one", Retrieved Value 2 will display the value "two", and Retrieved Value 3 will display the value "three".

Let's look at what happens behind the scenes after the RETRIEVE button is clicked.  Like the first form, clicking the command button, which in this form is called btnRetrieve, results in it's ON CLICK event firing.  This starts the following VBA event procedure (see screenshot below):

Above: The VBA event procedure for btnRetrieve.

The code begins by declaring a string variable called strOpenArgs before referencing the forms OpenArgs property and storing its value in the string.  (Just to recap, the value of the OpenArgs property (ie "one;two;three") was determined by the OpenArgs parameter of the  DoCmd.OpenForm command invoked when the user clicked the SUBMIT button on the previous form):

dim strOpenArgs As String
strOpenArgs = Me.OpenArgs

The next couple of lines of code are very important. A string array called strValues is declared and has its elements populated with data returned from a function called getOpenArgsArray.  This function is located in a separate module called Utilities which is global in scope.  This is where the core of the processing is done for this exercise:

Dim strValues() As String
strValues = getOpenArgsArray(strOpenArgs)

The purpose of the getOpenArgsArray is to split the value of its parameter, strOpenArgs (which in our case is "one;two;three"), into three separate strings, with each array element containing an individual string.  So for us, the strValues array is populated with the following values:

Array Element	Value
strValues(0)	"one"
strValues(1)	"two"
strValues(2)	"three"

These values are assigned to each of the three text boxes in the next six lines of code:

Me!txtRetValue1.SetFocus

Me!txtRetValue1.Text = strValues(0)

Me!txtRetValue2.SetFocus
Me!txtRetValue2.Text = strValues(1)

Me!txtRetValue3.SetFocus
Me!txtRetValue3.Text = strValues(2)

The end result can be seen in the screenshot below:

Above: the end result after the user clicks RETRIEVE.

In this way, we have used the DoCmd.OpenForm OpenArgs parameter to pass multiple values to a new form, thereby overcoming the limitation of only being able to pass a single string within the statement.

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Part Three: The getOpenArgsArray Function

However, this post would not be complete without an explanation of the getOpenArgsArray function, as this is where the core of the processing was done for this exercise.  Let's take a look at the code used in the getOpenArgsArray function:

Above: code for the getOpenArgsArray function.
NB: in this screenshot the strArgs array is declared with 7 elements.
This is because the function is global in scope and other event procedures using
 the function may need addtional elements.  This means that the OpenArgs
 parameter of DoCmd.OpenForm can pass up to 7 values with this current setup.
If more elements are needed, the array can be declared with an adjusted number as necessary.

As mentioned in section 2 above, the purpose of the getOpenArgsArray function is to split the value of the strOpenArgs parameter passed to the function, into individual sections, and to save each section as a separate array element. So in our case, the function receives a string containing the value "one;two;three", and returns an array with three elements ie 

Array Element	Value
Element 1	"one"
Element 2	"two"
Element 3	"three"

This is acheived by iterating through the strOpenArgs string in a FOR NEXT loop and appending each individual character to a temporary string called strBuildString.  Then when the current character of strOpenArgs in the loop is one of the semi-colons, the value of strBuildString is saved to a new array element. 

Lets break this down further.

The following three lines of code are concerned with iterating through each  character contained in the strOpenArgs string.  Each character is temporarily stored in a string variable called strChr:

For i = 1 To Len(strOpenArgs)
    Dim strChr As String
    strChr = Mid(strOpenArgs, i, 1)

The value of strChr is then checked to see whether or not it is a semi-colon.  If it is NOT a semi-colon, the character is appended to the strBuildString variable :

    If Not strChr = ";" Then
          strBuildString = strBuildString + strChr

If, on the other hand, the character IS a semi-colon, the current value of strBuildString is saved as a  new array element in strArgs().  The strBuildString variable is then cleared ready to build the value of the next array element:

         Else    
             strArgs(argCounter) = strBuildString

             strBuildString = ""

The element number of the array is kept track of in an integer variable called argCounter.  This is incremented by one after the strBuildString variable is cleared:

              argCounter = argCounter + 1
     End If

Next i

After the last iteration of strOpenArgs has completed, the final array element is saved, and the return value of the getOpenArgsArray function is set to the value of the strArgs() array:

strArgs(argCounter) = strBuildString
getOpenArgsArray = strArgs
Exit Function