nb_attachment

An expense without a receipt is a problem waiting for an approver. Odoo counts the attachments on an expense in a computed field, and this widget is what puts that count on the form in a form people read at a glance: a number beside a paperclip rather than a labelled integer.

It is one of the smallest widgets in Odoo core. A component, a template, and a single line in setup that copies the count off the record.

That single line carries a quirk worth knowing about. It reads the field by name literally, rather than through the name the field element supplies, which means the widget only works on a field actually called by that name. On any other field it renders nothing.

Receipt discipline is the whole battle in expense management. An expense with no attachment either gets rejected, which costs the employee a resubmission, or gets approved without evidence, which costs the company at audit. Making the count visible on the expense itself, rather than requiring someone to open the attachments panel, moves the check earlier.

The wider pattern is worth noting for any approval workflow: put the evidence count where the approval decision is made. It is a one line view change and it removes a category of back and forth entirely.

The core usage

<field name="nb_attachment" widget="nb_attachment"
       nolabel="1" readonly="True"/>

The field name and the widget name are the same, which is not a coincidence: the widget only works on that name.

What does not work

<!-- renders an empty counter -->
<field name="receipt_count" widget="nb_attachment"/>

The widget reads its own literal property name from the record, so a differently named field produces nothing.

A generic alternative

<button class="oe_stat_button" icon="fa-paperclip">
  <field name="receipt_count" widget="statinfo"/>
</button>

For any other model, the stat info widget gives the same idea without the name constraint.

There is very little code and two things worth recording about it.

The first is the literal field read. The component copies the count onto itself in setup using a fixed property name, ignoring the field name it was passed. That makes the widget non-portable in a way nothing announces: on a differently named field it renders without error and without a number.

The second is that the read happens in setup rather than in a getter, so the value is captured when the component is created. Attaching a receipt through the chatter updates the record's field, but the counter keeps its original value until the component is recreated. In practice the expense form reloads after an attachment operation often enough that this rarely shows, but on a custom form that avoids reloading, it will.

The registration is equally minimal: a component and nothing else. No supported types means the widget will not object to being placed on any field type, and no extractor means anything in the options dictionary is ignored.

Between Odoo 17 and Odoo 19 the only change is the removal of the module marker comment that Odoo 19 dropped across the codebase. The behavior has not moved.

Odoo 20 is expected at Odoo Experience in Brussels, 24 to 26 September 2026. The development branch is unstable and this may still change; we re-verify the page after release.

Byte-identical. The file on the development branch matches Odoo 19 exactly, including the literal field read and the capture in setup. Nothing about this widget changes in Odoo 20.