Power App Gallery Control / ForAll Gotcha

Recently, I came across a Power App gallery control / ForAll gotcha which I managed to handle so I’m sharing this here in case anyone else experiences the same issue.

OK, let’s set the scene: It’s a sunny Thursday afternoon in May in central Scotland. The hero is working on a Power App, and binds the following collection (colItems) to a gallery control:

ClearCollect(colItems,
    {
        ID:1,
        Name:"Dog"
    },
    {
        ID:2,
        Name:"Cat"
    },
    {
        ID:3,
        Name:"Rabbit"
    }
);

Great, the gallery is showing the data collection as expected!

Next up, I click a button which performs the following:

Clear(colTest1);

ForAll(galItems.AllItems,
    Collect(colTest1,
        {
            ID: txtID.Text,
            Name: txtName.Text
        }
    );
);

Cool, the colTest1 collection data looks good.

You know what, I want to use the As operator to alias each record as “locItem” to make future code easier to read when it becomes more complex later on. Let’s do that:

Clear(colTest2);

ForAll(galItems.AllItems As locItem,
    Collect(colTest2,
        {
            ID: txtID.Text,
            Name: txtName.Text
        }
    );
);

Woah, hang on! That’s not what I was expecting - the first record has been repeated!?

OK, let’s try a different approach: we’ll use the With function to alias the record as “locItem” instead:

Clear(colTest3);

ForAll(galItems.AllItems,
    With(
        {
            locItem:ThisRecord
        },
        Collect(colTest3,
            {
                ID: txtID.Text,
                Name: txtName.Text
            }
        );
    );
);

Yup, that’s now working as expected!

Notes

This issue was experienced in a real-world app and manifested itself further downstream, which was traced back to the gallery control / ForAll code similar to this example.

However, please note that this walkthrough of the issue and solution has been intentionally stripped-back to remove any “noise” and keep it easy to follow along with.

The real-world app had a very niche requirement to access all gallery control items as well as text input control values, and involved extra code.

Hope this helps if you experience something similar!