own pages/templates don't genereate page_name - odoo

Question

I am trying to add a breadcrumb entry to portal pages. I try to copy form the sale module. Inside this module there is this template that adds new breadcrumb entries:
<template id="portal_my_home_menu_sale" name="Portal layout : sales menu entries" inherit_id="portal.portal_breadcrumbs" priority="20">
<xpath expr="//ol[hasclass('o_portal_submenu')]" position="inside">
<li t-if="page_name == 'quote' or sale_order and sale_order.state in ('sent', 'cancel')" t-attf-class="breadcrumb-item #{'active ' if not sale_order else ''}">
<a t-if="sale_order" t-attf-href="/my/quotes?{{ keep_query() }}">Quotations</a>
<t t-else="">Quotations</t>
</li>
<li t-if="page_name == 'order' or sale_order and sale_order.state not in ('sent', 'cancel')" t-attf-class="breadcrumb-item #{'active ' if not sale_order else ''}">
<a t-if="sale_order" t-attf-href="/my/orders?{{ keep_query() }}">Sales Orders</a>
<t t-else="">Sales Orders</t>
</li>
<li t-if="sale_order" class="breadcrumb-item active">
<span t-field="sale_order.type_name"/>
<t t-esc="sale_order.name"/>
</li>
</xpath>
</template>
The templates I created don't have a page_name attribute. How can I add this to my templates?
Stock portal pages have home, order, or invoice as page_name but I couldn't find that in stock templates.

Answer 1

Variables settings are added either at the time of calling the render function or using t-set inside the template, or both.
On your particular case, page_name gets assigned inside portal_my_quotes (See <path_to_v12>/addons/sale/controllers/portal.py lines 39-90. See an excerpt below.) which is the controller for the route /my/quotes
#http.route(['/my/quotes', '/my/quotes/page/<int:page>'], type='http', auth="user", website=True)
def portal_my_quotes(self, page=1, date_begin=None, date_end=None, sortby=None, **kw):
values = self._prepare_portal_layout_values()
...
values.update({
'date': date_begin,
'quotations': quotations.sudo(),
'page_name': 'quote',
'pager': pager,
'archive_groups': archive_groups,
'default_url': '/my/quotes',
'searchbar_sortings': searchbar_sortings,
'sortby': sortby,
})
return request.render("sale.portal_my_quotations", values)
Documentation regarding the use of t-set can be found at https://www.odoo.com/documentation/12.0/reference/qweb.html#setting-variables