mail_composer_attachment_list

Attachments in Odoo's full email composer get their own widget. mail_composer_attachment_list takes the wizard's attachment_ids many2many and renders each file as a slim gray row: the filename as a link that opens or downloads the file, and a cross that removes it. That is the whole visible surface.

Technically it subclasses many2many_binary, the standard attachment field, and the interesting part is what the subclass removes. The stock widget renders an upload button and file cards; this one replaces the template with a bare list and no upload affordance at all. Files enter the composer through other doors, the paperclip button of the dialog, pasting into the body, or the records the composer inherited attachments from, and this widget is the single place they are reviewed and removed before sending.

The removal path is where the logic lives: beyond detaching the file from the field, the widget deletes pending composer attachments on the server and broadcasts the removal on the composer's event bus so the message body widget can delete any inline preview of the same file.

For users, this widget is the last checkpoint before a file leaves the company. The review-then-send habit is worth training: every row under the body is going out to the recipient, including files that arrived automatically because the email was composed from a record that already carried attachments, a quote PDF, a delivery slip, a signed contract. Sales teams that blind-send from templates occasionally ship the wrong revision precisely because nobody looks at these rows.

For administrators, the notable behavior is that removing a pending attachment really deletes it server side rather than leaving an orphan in ir.attachment. Odoo composers historically accumulated orphaned uploads from abandoned drafts; the 18 rework of the composer, this widget included, tightened that lifecycle.

And for anyone extending the composer: because the widget is intentionally upload-less, do not fight it. If your custom wizard needs an upload button in the list itself, use the parent many2many_binary instead and you get the standard uploader back.

How mail applies it (composer form)

<field name="attachment_ids" widget="mail_composer_attachment_list" nolabel="1"/>

If you need uploads, use the parent instead

<field name="attachment_ids" widget="many2many_binary"
       options="{'accepted_file_extensions': '.pdf,.png'}"/>

Same field, same storage model, plus the standard Attach button that this composer variant strips away.

The remove flow, read line by line from the 19.0 source, does three distinct things in order.

Detach. The inherited onFileRemove drops the id from the many2many, which is all the stock widget ever does.

Delete, conditionally. The subclass then looks the attachment up in the mail store and, only when its res_model is mail.compose.message, calls the attachment upload service to unlink it on the server. The guard matters: attachments that belong to the source business record, say the invoice you are emailing, are merely detached from this email and survive on the invoice. Only files uploaded for this draft die with the draft.

Broadcast. Finally it triggers ATTACHMENT_REMOVED on env.fullComposerBus. The body widget listens and strips every element with the matching data-attachment-id, so a pasted image does not linger in the text after its chip is gone.

A version footnote worth knowing: in Odoo 18 that bus trigger was unconditional, so mounting the widget outside the full composer dialog, where the bus does not exist, threw on every removal. 19 added the optional chaining that makes the widget usable standalone, which is also what lets the scheduled message dialog share it safely.

Odoo 20 is expected at Odoo Experience in Brussels, 24 to 26 September 2026. Findings below are from the public development branch, which remains unstable until release; we re-verify against the shipped version.

The custom template disappears. On master the widget no longer overrides the list template. Instead it swaps in a subclassed row component on the new Many2XBinary base that the attachment widgets are being rebuilt on, and the service call signature changes to take a list (unlink([attachment])). Visual result is similar; the extension point moves from template inheritance to component substitution, which is exactly where custom composer styling will break.

The conditional server delete and the bus broadcast survive unchanged, so the behavioral contract described above is stable so far. As always with the development branch, we re-check this page once Odoo 20 ships, and our migration team tracks the Many2XBinary rework across all attachment widgets.