Wagtail: Adding author filtering

blog models.py

# blog/models.py

# Nothing in this class has changed. I just put it here for reference. 
class BlogAuthor(models.Model):
    """Blog author for snippets."""

    name = models.CharField(max_length=100)
    website = models.URLField(blank=True, null=True)
    image = models.ForeignKey(
        "wagtailimages.Image",
        on_delete=models.SET_NULL,
        null=True,
        blank=False,
        related_name="+",
    )
    
   
# Added filterable context based on the ?author=x query string parameter
class BlogListingPage(RoutablePageMixin, Page):
    """Listing page lists all the Blog Detail Pages."""

    # Fields here

    def get_context(self, request, *args, **kwargs):
        """Adding custom stuff to our context."""
        context = super().get_context(request, *args, **kwargs)
        # Get all posts
        all_posts = BlogDetailPage.objects.live().public().order_by('-first_published_at')

        # This is the filterable part. 
        # Start author filter.
        if request.GET.get('author', None):
            author_id = request.GET.get('author')
            all_posts = all_posts.filter(blog_authors__author__id=author_id)
        # End author filter.
        
        # Paginate all posts by 2 per page
        paginator = Paginator(all_posts, 2)
        # Try to get the ?page=x value
        page = request.GET.get("page")
        try:
            # If the page exists and the ?page=x is an int
            posts = paginator.page(page)
        except PageNotAnInteger:
            # If the ?page=x is not an int; show the first page
            posts = paginator.page(1)
        except EmptyPage:
            # If the ?page=x is out of range (too high most likely)
            # Then return the last page
            posts = paginator.page(paginator.num_pages)

        # "posts" will have child pages; you'll need to use .specific in the template
        # in order to access child properties, such as youtube_video_id and subtitle
        context["posts"] = posts
        return context

blog_listing_page.html

{% extends "base.html" %}
{# templates/blog/blog_listing_page.html #}

{% block content %}
    {% for post in posts %}
        <h2>{{ post.custom_title }}</h2>
        <div>
            Posted by:
            {% for orderable in post.blog_authors.all %}
                <a href="/blog/?author={{ orderable.author.id }}">{{ orderable.author.name }}</a>
            {% endfor %}
        </div>
    {% endfor %}
{% endblock %}