Navigation indexes are not rendered correctly on the Blog index from the second page onwards

[vedranmiletic]

Context

No response

Bug description

When using blog plugin with navigation.indexes feature, only the first page of the Blog index has the correctly rendered navigation. Other pages of the Blog index are rendered as if the feature is not enabled.

Interestingly enough, this happens only when there is at least three pages of posts in the Blog index.

Blog archive is affected the same way. I haven't checked if categories are affected since we don't use them.

Additionally, if the tags plugin is enabled, the Tags page will exhibit the same behavior regarding the rendering of the Blog index in the navigation. I have not included this in the minimal example on purpose to keep it minimal, but it can be observed on our group website. I can prepare a less minimal example if needed.

Related links

• Reporting a bug
• Setting up navigation

Reproduction

9.2.8-navigation.zip

Steps to reproduce

1. mkdocs serve
2. look at the navigation in first page of the Blog index
3. see it is rendered as intended
4. navigate to the second or the third page
5. see it is rendered as if it would be without navigation.indexes feature enabled

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.

[balansczerni]

I guess I have the same error?

I thought it was because I set tags_extra_files. In my case, the error occurs when more than 10 files appear in the posts directory and only occurs with (and from location of) tags_extra_files.

It's hard for me to describe it better so I'm attaching a minimal reproduction:
9.2.8+insiders.4.40.4-blog-vs-indexes.zip

.
├─ docs/
│  └─ blog/
│     ├─ subset.md
│     ├─ posts/
│     └─ index.md
└─ mkdocs.yml

mkdocs.yml:

theme:
  name: material
  features:
    - navigation.indexes

plugins:
  #- info
  - blog
  - tags:
      tags_extra_files:
        blog/subset.md:
          - mytag

nav:
  - Page: index.md
  - Blog:
    - blog/index.md
    - Subset page: blog/subset.md  
  - Tags: tags.md

extra:
  tags:
    My tag: mytag

In addition, I think I have located the place in the code where the bug takes place (this is from nav-item.html with my comments):

{% macro render(nav_item, path, level) %}
  {% set class = "md-nav__item" %}
  {% if nav_item.active %}
    {% set class = class ~ " md-nav__item--active" %}
  {% endif %}
  {% if nav_item.children %}
    {% set indexes = [] %}
    {% if "navigation.indexes" in features %}
      {% for nav_item in nav_item.children %}
        {% if nav_item.is_index and not index is defined %}
          {% set _ = indexes.append(nav_item) %}
        {% endif %}
      {% endfor %}
      {% endif %}
  
    {% if "navigation.sections" in features and level == 1 + (
      "navigation.tabs" in features
    ) %}
      {% set class = class ~ " md-nav__item--section" %}
    {% elif not nav_item.active and "navigation.prune" in features %}
      {% set class = class ~ " md-nav__item--pruned" %}
      {% set prune = true %}
    {% endif %}
    <li class="{{ class }} md-nav__item--nested">
      {% if not prune %}
        {% set expanded = "navigation.expand" in features %}
        {% set active = nav_item.active or expanded %}
        {% set checked = "checked" if nav_item.active %}
        {% if expanded and not checked %}
          {% set indeterminate = "md-toggle--indeterminate" %}
        {% endif %}
        <input class="md-nav__toggle md-toggle {{ indeterminate }}" type="checkbox" id="{{ path }}" {{ checked }}>
        {% if not indexes %}
          <label class="md-nav__link" for="{{ path }}" id="{{ path }}_label" tabindex="0">
            {{ render_content(nav_item) }} 🆘 This is "extra" blog link.
            <span class="md-nav__icon md-icon"></span>
          </label>
        {% else %}
          {% set index = indexes | first %}
          {% set class = "md-nav__link--active" if index == page %}
          <div class="md-nav__link md-nav__container">
            <a href="{{ index.url | url }}" class="md-nav__link {{ class }}">
              {{ render_content(index, nav_item) }} ✅ This is proper link for blog.
            </a>
            {% if nav_item.children | length > 1 %}
              <label class="md-nav__link {{ class }}" for="{{ path }}">
                <span class="md-nav__icon md-icon"></span>
              </label>
            {% endif %}
          </div>
        {% endif %}

[squidfunk]

Thanks to both of you for the reproductions – we'll look into it asap!

[smokedlinq]

FYI this also affects non-blog sites.

[squidfunk]

Fixed in 433c137. Paginated views did not correctly check if the base view is an index page or not. Now, if the view is an index page (i.e. is called index.md or README.md), paginated pages are also generated as index pages.

@smokedlinq I'm not sure where or how this happens for non-blog sites, as the issue reported is exclusive to the blog plugin. Please open a new issue with a minimal reproduction, so we can look into it.

[squidfunk]

@vedranmiletic if this does not solve the problem for the tags plugin, please create a new issue.

[vedranmiletic]

@squidfunk thanks, it seems to work correctly now, both for tags page and blog index pages after the first one.

[squidfunk]

Released as part of 9.4.2.