Answered

Populate multi select combobox with comma delim str from SP - then submit change back to SP

(2) Share

Report

Posted on by cardinalnight

212

I have a multi select combobox (classic) which allows me to submit and retrieve multiple selections of strings. Here are the Properties of the combo box:

DefaultSelectedItems: Split(varEventLocation, ",")

Items: Sites
 
The app has a gallery which the user clicks an edit button to retrieve all the data from SP. The Edit button populates the combo box like this:
Reset(cmbNewFormLocation); //First blank the variable and reset the control
Set(
    varEventLocation,
    Blank()
);
Set( //Then get the item and store it in a variable (varSelectedSubmission)
    varSelectedSubmission,
    ThisItem
);
// Get the object for further manipulation and data extraction later: 
Set(
    varSelectedSubmissionID,
    varSelectedSubmission.ID
);
With( 
    {
        wSubmission: LookUp(
            CPDEventSessions,
            ID = varSelectedSubmissionID
        )
    },
  Set( // Store the retrieved comma delimited string into the variable:
        varEventLocation,
        wSubmission.EventLocation
    );
 
The problem is that if the user retrieves an existing SP list item, goes into the form and then changes the selections in the combo box, then clicks a Save to SharePoint button, it doesn't save the updated combo box.
Here is the Save formula on the Save to SharePoint button:
    // If varItemID is not blank, update the existing item
    Patch(
        CPDEventSessions,
        LookUp(
            CPDEventSessions,
            ID = varItemID
        ),
        {
  EventLocation: If(
                !IsBlank(varEventLocation), //This If is an attempt at submitting the variable if not blank, otherwise submit the control values (cmbNewFormLocation). Doesn't work.
                varEventLocation,
                Left(
                    Concat(
                        cmbNewFormLocation.SelectedItems,
                        Title & ","
                    ),
                    Len(
                        Concat(
                            cmbNewFormLocation.SelectedItems,
                            Title & ","
                        )
                    ) - 1
                )
            ),
} etc..
Things I've tried:
Updating the variable in the OnChange property of the combo box: Set(varEventLocation, varEventLocation) (!?) - doesn't work, causes loops and unintended consequences!
 

Categories:

Building Power Apps

I have the same question (0)

All responses (2)

Answers (1)

Verified answer

Ravi-Prajapati 416 Super User 2025 Season 2 on at

Like (2)

Report
Step 1: Ensure varEventLocation Updates Dynamically

Right now, varEventLocation is only being set when loading the form. It does not capture changes when users select/deselect items. To fix this, update the OnChange property of the ComboBox:

powerapps

Set( varEventLocation, Concat( cmbNewFormLocation.SelectedItems, Title & "," ) )

✅ This ensures varEventLocation always reflects the latest selections.

Step 2: Modify the Save (Patch()) Formula

Your Patch() function is trying to save either varEventLocation or the ComboBox selection, but varEventLocation may not be up-to-date. Instead, modify it like this:

powerapps

Patch( CPDEventSessions, LookUp(CPDEventSessions, ID = varItemID), { EventLocation: Left( Concat( cmbNewFormLocation.SelectedItems, Title & "," ), Len(Concat(cmbNewFormLocation.SelectedItems, Title & ",")) - 1 ) } );

✅ This directly uses cmbNewFormLocation.SelectedItems instead of varEventLocation.
✅ The Left(..., Len(...)-1) part removes the trailing comma from the final string.

Step 3: Remove varEventLocation from Form Population

Since we are now handling selections directly from the ComboBox, we no longer need to store selections in varEventLocation. Instead, update the DefaultSelectedItems property of cmbNewFormLocation:

powerapps

Split(ThisItem.EventLocation, ",")

✅ This means selections are taken directly from SharePoint, avoiding unnecessary variables.

Final Solution Summary

✔ OnChange of ComboBox:

powerapps

Set( varEventLocation, Concat( cmbNewFormLocation.SelectedItems, Title & "," ) )

✔ DefaultSelectedItems of ComboBox:

powerapps

Split(ThisItem.EventLocation, ",")

✔ Save Button (Patch())

powerapps

Patch( CPDEventSessions, LookUp(CPDEventSessions, ID = varItemID), { EventLocation: Left( Concat( cmbNewFormLocation.SelectedItems, Title & "," ), Len(Concat(cmbNewFormLocation.SelectedItems, Title & ",")) - 1 ) } );

Was this reply helpful? Yes No
Suggested answer

Michael E. Gernaey 53,362 Super User 2025 Season 2 on at

Like (1)

Report

HI

I am not following why you have all these variables?

I don't mean I need to understand how they work, I am trying to understand why you have them. They click the Gallery Item and then what? Do they stay on the same screen and a form populates or is it another screen?

What is the exact Column type in the back end for this multi-select situation? Choice? String? LookUp?

Happy to help you solve, but I assume you are NOT usinhg Submit for a specific reason, just not sure why

Thanks!

Was this reply helpful? Yes No