Basic OpenGraph support (#267)

Creates an OpenGraph template include in base.html including the basic tags expected on all pages.

Then allows any page to add additional expected tags via `context`.

Currently, profiles and posts are enriched to show complete opengraph metadata, and render correctly in Discord.

Note: This does not show posts in Slack like Twitter/Mastodon do. I believe this is due to Slack preferring oembed when present, which is a mastodon API endpoint we may need to create at some point.

activities/models/post.py

@@ -838,6 +838,22 @@ class Post(StatorModel):
                 raise ValueError("Actor on delete does not match object")
             post.delete()
 
+    ### OpenGraph API ###
+
+    def to_opengraph_dict(self) -> dict:
+        return {
+            "og:title": f"{self.author.name} (@{self.author.handle})",
+            "og:type": "article",
+            "og:published_time": (self.published or self.created).isoformat(),
+            "og:modified_time": (
+                self.edited or self.published or self.created
+            ).isoformat(),
+            "og:description": (self.summary or self.safe_content_local()),
+            "og:image:url": self.author.local_icon_url().absolute,
+            "og:image:height": 85,
+            "og:image:width": 85,
+        }
+
     ### Mastodon API ###
 
     def to_mastodon_json(self, interactions=None):

activities/templatetags/opengraph.py

@@ -0,0 +1,23 @@
+from django import template
+
+register = template.Library()
+
+
+@register.filter
+def dict_merge(base: dict, defaults: dict):
+    """
+    Merges two input dictionaries, returning the merged result.
+
+    `input|dict_merge:defaults`
+
+    The defaults are overridden by any key present in the `input` dict.
+    """
+    if not (isinstance(base, dict) or isinstance(defaults, dict)):
+        raise ValueError("Filter inputs must be dictionaries")
+
+    result = {}
+
+    result.update(defaults)
+    result.update(base)
+
+    return result

activities/views/posts.py

@@ -39,11 +39,15 @@ class Individual(TemplateView):
             # Show normal page
             return super().get(request)
 
-    def get_context_data(self):
+    def get_context_data(self, **kwargs):
+        context = super().get_context_data(**kwargs)
+
         ancestors, descendants = PostService(self.post_obj).context(
             self.request.identity
         )
-        return {
+
+        context.update(
+            {
                 "identity": self.identity,
                 "post": self.post_obj,
                 "interactions": PostInteraction.get_post_interactions(
@@ -54,6 +58,9 @@ class Individual(TemplateView):
                 "ancestors": ancestors,
                 "descendants": descendants,
             }
+        )
+
+        return context
 
     def serve_object(self):
         # If this not a local post, redirect to its canonical URI

core/context.py

@@ -8,4 +8,10 @@ def config_context(request):
             request.identity.config_identity if request.identity else None
         ),
         "top_section": request.path.strip("/").split("/")[0],
+        "opengraph_defaults": {
+            "og:site_name": Config.system.site_name,
+            "og:type": "website",
+            "og:title": Config.system.site_name,
+            "og:url": request.build_absolute_uri(),
+        },
     }

templates/_opengraph.html

@@ -0,0 +1,14 @@
+{% load opengraph %}
+{% with opengraph_merged=opengraph_local|dict_merge:opengraph_defaults %}
+    <!-- Begin OpenGraph tagging -->
+    {% for key, value in opengraph_merged.items %}
+        <meta content="{{ value|striptags }}" property="{{ key }}"/>
+        {% if key == "og:description" %}
+            {# Mastodon duplicates this one tag without the og: prefix. Not sure why #}
+            <meta content="{{ value|striptags }}" property="description"/>
+        {% endif %}
+    {% endfor %}
+    {% block opengraph_extra %}
+    {% endblock %}
+    <!-- End OpenGraph tagging -->
+{% endwith %}

templates/activities/post.html

@@ -2,6 +2,10 @@
 
 {% block title %}Post by {{ post.author.html_name_or_handle }}{% endblock %}
 
+{% block opengraph %}
+    {% include "_opengraph.html" with opengraph_local=post.to_opengraph_dict %}
+{% endblock %}
+
 {% block content %}
     {% for ancestor in ancestors reversed %}
         {% include "activities/_post.html" with post=ancestor reply=True link_original=False %}

templates/base.html

@@ -26,6 +26,9 @@
     {% if config_identity.custom_css %}
       <style>{{ config_identity.custom_css }}</style>
     {% endif %}
+    {% block opengraph %}
+        {% include "_opengraph.html" with opengraph_local=opengraph_defaults %}
+    {% endblock %}
     {% block extra_head %}{% endblock %}
 </head>
 <body class="{% block body_class %}{% endblock %}" hx-headers='{"X-CSRFToken": "{{ csrf_token }}"}'>

templates/identity/view.html

@@ -2,6 +2,10 @@
 
 {% block title %}{{ identity }}{% endblock %}
 
+{% block opengraph %}
+    {% include "_opengraph.html" with opengraph_local=identity.to_opengraph_dict %}
+{% endblock %}
+
 {% block extra_head %}
     {% if identity.local %}
         <link rel="alternate" type="application/rss+xml" title="RSS feed for {{ identity.name }}" href="rss/" />

users/models/identity.py

@@ -735,6 +735,19 @@ class Identity(StatorModel):
                 await sync_to_async(self.save)()
         return True
 
+    ### OpenGraph API ###
+
+    def to_opengraph_dict(self) -> dict:
+        return {
+            "og:title": f"{self.name} (@{self.handle})",
+            "og:type": "profile",
+            "og:description": self.summary,
+            "og:profile:username": self.handle,
+            "og:image:url": self.local_icon_url().absolute,
+            "og:image:height": 85,
+            "og:image:width": 85,
+        }
+
     ### Mastodon Client API ###
 
     def to_mastodon_json(self):