How to prevent attachment file duplicates

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Posted on by CU20031912-2

Hi all,

I’m trying to prevent users from submitting duplicate files in the attachment section.

I added the following logic in the OnAddFile property. It successfully detects duplicate files, but it does not remove the duplicate from the attachment control.

I would prefer not to use Reset(Self), since that would remove all files. Instead, I’d like to:

- remove only the duplicate file, or

- ensure that if the same file is uploaded multiple times, it only appears once in the attachments list.

With(

{ newName: Lower(Last(Self.Attachments).Name) },

    If(

        CountIf(Self.Attachments As f, Lower(f.Name) = newName) > 1,

        Notify("This file has already been uploaded.")

    )

)

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WarrenBelz 155,352 Most Valuable Professional on at

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Hi @CU20031912-2,

This should work for you - put this OnAddFile of the Attachment Control
If( CountIf( colAttach, Lower(Name) = Lower(Last(Self.Attachments).Name) ) > 0, Notify( "This file has already been uploaded", NotificationType.Error, 5000 ); Reset(Self), Collect( colAttach, Last(Self.Attachments) ) )

and set the Items of the Attachment control to
colAttach

The problem is that you cannot programatically delete an item from an attachment control, so you nned to use a collection for the Items and manage that. Resetting the control in this instance will "delete" the new item and revert it back to the existing collection without it added.

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11manish 2,293 on at

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You’re very close — the challenge here is a limitation of the Attachment control in Microsoft Power Apps.

Key Limitation (Important)

The Attachment control is not fully controllable

You cannot remove a single file programmatically

Reset(Self) → removes ALL files only

No API to delete just one attachment

So your current approach detects duplicates , but cannot remove them

Best Solution (Recommended Pattern)

Control uploads using a temporary collection

Instead of relying directly on Self.Attachments, you:

Intercept → Validate → Store only unique files

Step-by-step solution
1. Create a collection

ClearCollect(colAttachments, [])

2. Use OnAddFile logic

Replace your code with:

With(
{ newFile: Last(Self.Attachments) },
If(
CountIf(colAttachments, Lower(Name) = Lower(newFile.Name)) > 0,
Notify("This file has already been uploaded."),

Collect(colAttachments, newFile)
)
)

3. Reset control (safe now)

Reset(Self)

Why this works:

You store only valid files

Reset clears UI

Then you re-bind from collection

4. Bind attachment control

Set:

Items = colAttachments

Thanks
Manish

Visit my blog : https://powerappbuilder.blogspot.com/

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WarrenBelz 155,352 Most Valuable Professional on at

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@11manish,

That is exactly what I posted . . .

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WarrenBelz 155,352 Most Valuable Professional on at

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Hi @CU20031912-2,

A quick follow-up to see if you received the answer you were looking for. Happy to assist further if not.

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CU02041602-0 2 on at

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Hi @WarrenBelz

This is very helpful but I have a query regarding uploading multiple files at once . If I have to attach more than two files at a time, so it will work fine or it will get issue.

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WarrenBelz 155,352 Most Valuable Professional on at

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Hi @CU20031912-2,

This is a very tricky one - I spent some time on a model, and this seems to work. First when you open the Form, you need to initialise a couple of Collections with the records you are working on - you might do this when you navigate to the record,
ClearCollect( colFiles, LookUp( YourSPList, ID = YourID ).Attachments ); ClearCollect( colTemp1, ForAll( colFiles As _Files, { Value: _Files.Value, Name: _Files.DisplayName, DisplayName: _Files.DisplayName, Id: _Files.Id, AbsoluteUri: _Files.AbsoluteUri } ) );

This gets the existing attachments - the structure accounts for files already stored as there are additional values not present if you just collect the Attachment Control contents.

The Items of your Attachment Control

If( IsEmpty(colFiles), ThisItem.Attachments, colFiles )

Now put this OnAddFile of the Attachment Control

Clear(colTemp2); Collect( colTemp1, Self.Attachments ); With( { _Names: Distinct( colTemp1, Lower(DisplayName) ) }, Collect( colTemp2, ForAll( _Names As _N, LookUp( colTemp1, Lower(DisplayName) = _N.Value ) ) ); ClearCollect( colFiles, colTemp2 ); Reset(Self); If( CountRows(_Names) <> CountRows(colTemp1), Notify( "Duplicates removed", NotificationType.Information, 5000 ) ) );

Esentially, you are collecting the entire contents of the attachment control and adding it to whatever was there before (so you will have duplicates of both existing items and anything duplicate the user has added, then you find a unique set of it all to create the Collection forming the Items of the Attachment control. A couple of counts are done then done to see if the number of attachments has been reduced by applyng the Distinct filter.

and OnRemoveFile

RemoveIf( colFiles, DisplayName = ThisItem.DisplayName )

There still may be some glitches - but best effort considering the system was never designed to do this.

Please ✅ Does this answer your question if my post helped you solve your issue. This will help others find it more readily. It also closes the item. If the content was useful in other ways, please consider answering Yes to Was this reply helpful? or give it a Like ♥
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