How to repeat the invoice number on each pages of an invoice PDF

Question

I need to show the invoice number in all pages of a same invoices when I generate the invoice PDF for downloading or printing. How can I do that?

Answer 1

<template id="external_layout_header_inherited" inherit_id="report.external_layout_header">
    <xpath expr="//div[@class='header']" position="inside">
        <div t-if="o.number">Ref.: <span t-field="o.number"/></div>
    </xpath>
</template>