Status: Public Preview — behaviour may change.

What it does

A modern-theme control for adding, downloading and removing files tied to a record. Unlike the classic Attachments control, it works outside a form, and its Attachments output can go straight into Patch. Inside a form, SubmitForm saves the record and its files together.

Key facts

• Preview. Turn on modern controls and themes for the app first.
• Core properties: Items, MaxAttachments, MaxAttachmentSize (MB per new file), AcceptedFileTypes (a one-column table of extensions) and DisplayMode (Edit, View, Disabled).
• Outputs and events: Attachments, AttachmentsCount (excludes files marked for removal), IsUploading, OnAddFile, OnRemoveFile, OnSelect and OnError.
• It shows saved files, unsaved additions and files marked for removal differently, and supports a file picker plus web drag-and-drop.
• Microsoft documents three patterns: Dataverse attachments through an edit form, a single file into a Dataverse file column with Patch, and SharePoint list attachments with Patch and the control's Attachments output.
• Dataverse attachments need attachments enabled on the table, which isn't the same as adding a file column. A file column holds one file per record.

When to use / skip

Use it in new modern-theme apps where users attach evidence, receipts or supporting documents, particularly when you want to save without a form. Skip it for production apps that can't take preview risk, and for anything with a heavy upload workflow where you'd rather control the experience yourself.

Configuration decisions

• Attachment column on the table, or a single file column per record.
• MaxAttachments and MaxAttachmentSize limits, and whether the data source's own limits are tighter.
• Which file types to accept, understanding the list guides selection but isn't validation.
• Whether saving happens through a form or a Patch from a button.

Gotchas

• Adding a file doesn't save it. The file is staged in the app until Patch or SubmitForm runs. Users who close the screen after "uploading" lose it.
• IsUploading isn't a save confirmation. It only covers files being loaded into the control's memory.
• OnAddFile fires once per file, not once per batch, so don't put heavy logic in it.
• A file column takes one file. Passing the whole Attachments table to it won't work; you build a record with FileName and Value from the first file.
• Clearing the control doesn't delete stored files. A successful save and a reset leave the saved file in the column.
• Type restrictions are cosmetic. AcceptedFileTypes doesn't stop a determined user, and doesn't invalidate files already saved.

Consultant notes

• Make users see the save step. A visible Save button and a notification on success cuts "I attached it but it's gone" tickets.
• Treat the file-type list as UX, and put the real controls in Dataverse, SharePoint or your DLP and malware policies.
• Plan for the classic control still being on screens you inherit. They behave differently enough that mixing both in one form is asking for confusion.
• Preview means no support commitment, so say so before it lands in a go-live scope.

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Revisit when the Attachments control leaves preview or the Dataverse file column pattern changes.