Page meta attribute missing in include

[DevOpsJeremy]

Context

No response

Bug description

If I include a file in a template with includes and try to use page-level variables with {{ page.meta.my_var }}, mkdocs build throws the following error:

jinja2.exceptions.UndefinedError: 'None' has no attribute 'meta'

To confirm that the variable exists, I check Meta: {{ page.meta }}:

Meta: {'my_var': 'this is my var'}

But if I use the default() filter: Variable: {{ ( page.meta | default("") ).my_var }}, it works.

Variable: this is my var

The meta attribute obviously exists, but for some reason I have to use default() in order to access it and the page-level variables.

This is what happens when I use just {{ page.meta.my_var }}:

> mkdocs build -c
INFO    -  Cleaning site directory
INFO    -  Building documentation to directory: /mkdocs/site
Traceback (most recent call last):
  File "/usr/local/bin/mkdocs", line 8, in <module>
    sys.exit(cli())
             ^^^^^
  File "/usr/local/lib/python3.11/site-packages/click/core.py", line 1161, in __call__
    return self.main(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/click/core.py", line 1082, in main
    rv = self.invoke(ctx)
         ^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/click/core.py", line 1697, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/click/core.py", line 1443, in invoke
    return ctx.invoke(self.callback, **ctx.params)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/click/core.py", line 788, in invoke
    return __callback(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/mkdocs/__main__.py", line 288, in build_command
    build.build(cfg, dirty=not clean)
  File "/usr/local/lib/python3.11/site-packages/mkdocs/commands/build.py", line 328, in build
    _build_theme_template(template, env, files, config, nav)
  File "/usr/local/lib/python3.11/site-packages/mkdocs/commands/build.py", line 103, in _build_theme_template
    output = _build_template(template_name, template, files, config, nav)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/mkdocs/commands/build.py", line 83, in _build_template
    output = template.render(context)
             ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/jinja2/environment.py", line 1295, in render
    self.environment.handle_exception()
  File "/usr/local/lib/python3.11/site-packages/jinja2/environment.py", line 942, in handle_exception
    raise rewrite_traceback_stack(source=source)
  File "/usr/local/lib/python3.11/site-packages/material/templates/404.html", line 4, in top-level template code
    {% extends "main.html" %}
  File "/mkdocs/overrides/main.html", line 1, in top-level template code
    {% extends "base.html" %}
  File "/usr/local/lib/python3.11/site-packages/material/templates/base.html", line 140, in top-level template code
    {% block header %}
^^^^^^^^^^^^^^^^^^^^^^^
  File "/mkdocs/overrides/main.html", line 4, in block 'header'
    {% include "header.html" %}
^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/mkdocs/overrides/header.html", line 2, in top-level template code
    <div>page.meta.my_var (header): {{ page.meta.my_var }}</div>
    ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/jinja2/environment.py", line 490, in getattr
    return getattr(obj, attribute)
           ^^^^^^^^^^^^^^^^^^^^^^^
jinja2.exceptions.UndefinedError: 'None' has no attribute 'meta'

This only occurs on HTML files pulled in with includes. In the regular template like main.html, I can use {{ page.meta.my_var }} just fine.

Related links

• Reporting a bug

Reproduction

mkdocs.zip

Steps to reproduce

This is my configuration:

docs/mydoc.md

---
my_var: this is my var
---
# Introduction

Hello world

overrides/main.html

{% extends "base.html" %}
{% block header %}
    {{ super() }}
    {% include "header.html" %}
{% endblock %}
{% block content %}
    {{ super() }}
    <div>page.meta.my_var (main): {{ page.meta.my_var }}</div>
{% endblock %}

mkdocs.yml

site_name: my_site
use_directory_urls: false
theme:
  name: material
  custom_dir: overrides

This works
overrides/header.html

<div>page.meta (header): {{ page.meta }}</div>
<div>page.meta.my_var (header): {{ ( page.meta | default("") ).my_var }}</div>

This doesn't work:
overrides/header.html

<div>page.meta (header): {{ page.meta }}</div>
<div>page.meta.my_var (header): {{ page.meta.my_var }}</div>

Browser

No response

Before submitting

• I have read and followed the bug reporting guidelines.
• I have attached links to the documentation, and possibly related issues and discussions.
• I assure that I have removed all customizations before submitting this bug report.
• I have attached a .zip file with a minimal reproduction using the built-in info plugin.

[squidfunk]

Thanks for reporting. This is not an issue with Material for MkDocs, but a problem with customization of MkDocs/Jinja. I'm converting this to a discussion, as somebody else might be able to help you debug this.

[kamilkrzyskow]

Hello @DevOpsJeremy,
you need to remember that your Jinja template runs not only for your Pages (which are derived from Markdown files), but also for other static templates like the 404.html page (only this one by default), and these don't have any page.meta, hence the None error.

File "/usr/local/lib/python3.11/site-packages/material/templates/404.html", line 4, in top-level template code

So to handle such cases always do a safety guard if page.meta and page.meta.variable, which can be seen in the docs:

• https://squidfunk.github.io/mkdocs-material/reference/#on-a-single-page

{% if page and page.meta and page.meta.robots %}

I think that if page is not necessary anymore after an MkDocs fix, just the page.meta and page.meta.robots check

I think that MkDocs could make things easier and add a page.meta = {} for these static templates to prevent the odd None error, so you could double check upstream if there are any open issues and if not report it there ✌️

[kamilkrzyskow]

I see you've moved onto more complex things, so I'll mark this as the answer 👌

• With a custom theme, how to create filters/extensions that are automatically available without being defined in the plugins? mkdocs/mkdocs#3943