Filtering List A for the items that are not in List B

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Posted on by MS-19111917-0

I have two lists: List A and List B. List A has Project Number column (Single line of text) and List B has Project Number column (Lookup Column) pulling data from List A. For List B, I have SharePoint integrated form and in that form for Project Number(Lookup Column), I want to show only Project Numbers that are in List A but there is no existing item of same Project number in List B (i.e. the Project numbers that are in List A but not in List B). I need help in filetring the project Number.

Should I create a collection for List B Project Number column so filtering doesn't impact the form performance. I am also trying to avoid delegation in Filtering the Project Column.

I appreciate any help on it.

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Power Apps Pro Dev & ISV

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Inogic 1,135 Moderator on at

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Hi,

To achieve this in your Canvas App, you can:

Create a collection for List B's Project Numbers to improve performance and avoid delegation issues.

Filter List A to show only Project Numbers not used in List B.

Step-by-Step Solution

1. Create a Collection for List B Project Numbers
This will store all existing Project Numbers from List B.
ClearCollect(
    colListBProjectNumbers,
    ShowColumns(ListB, "ProjectNumber") // Assuming "ProjectNumber" is the lookup column's name
)
Run this on the app's start (OnStart) or when the form loads.

2. Filter List A for Available Project Numbers
Use this filtered data as the Items property of the dropdown or combo box for the Project Number lookup.
Filter(
    ListA,
    !(ProjectNumber in colListBProjectNumbers.ProjectNumber)
)
This filters out any Project Numbers already present in List B.
3. Set the Dropdown/Combo Box Items
If you're using a ComboBox for the Project Number in List B’s form, set its Items property to:
Filter(
    ListA,
    !(ProjectNumber in colListBProjectNumbers.ProjectNumber)
)
For a Dropdown:
Distinct(
    Filter(ListA, !(ProjectNumber in colListBProjectNumbers.ProjectNumber)),
    ProjectNumber
)

Why Use a Collection?

It improves performance by reducing delegation issues.

Collections are loaded once and used locally, making filtering faster.

Hope this helps.

Thanks!

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MS-19111917-0 35 on at

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Thank you for your response @Inogic. My List A has more than 2500 items. For step, 2 and 3 (Filter(
ListA,
!(ProjectNumber in colListBProjectNumbers.ProjectNumber)
)) can we use delegable function? 'In' doesn't pull all the data from the list. Could you please help with Delegation?

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