Add include_md template tag.

Author: adamghill

coltrane/renderer.py

@@ -31,16 +31,15 @@ class StaticRequest:
     path: str
 
 
-def _get_markdown_content_as_html(slug: str) -> Dict[str, Optional[Dict]]:
+def render_markdown_path(path) -> Dict[str, Optional[Dict]]:
     """
-    Converts markdown file based on the slug into HTML.
+    Renders the markdown file located at path.
     """
 
-    file_path = get_content_directory() / f"{slug}.md"
     markdown_extras = get_markdown_extras()
 
     content = markdown_path(
-        file_path,
+        path,
         extras=markdown_extras,
     )
 
@@ -51,7 +50,17 @@ def _get_markdown_content_as_html(slug: str) -> Dict[str, Optional[Dict]]:
     return (str(content), metadata)
 
 
-def _render_html_with_django(
+def _get_markdown_content_as_html(slug: str) -> Dict[str, Optional[Dict]]:
+    """
+    Converts markdown file based on the slug into HTML.
+    """
+
+    path = get_content_directory() / f"{slug}.md"
+
+    return render_markdown_path(path)
+
+
+def render_html_with_django(
     html: str, context: Dict, request: HttpRequest = None
 ) -> str:
     """
@@ -112,7 +121,7 @@ def render_markdown(
     context["data"] = data
 
     # Add rendered content to the context
-    content = _render_html_with_django(html, context, request)
+    content = render_html_with_django(html, context, request)
     context["content"] = mark_safe(content)
     template = context["template"]
 

coltrane/templatetags/coltrane_tags.py

@@ -1,9 +1,16 @@
 from typing import Dict
 
 from django import template
+from django.template.base import Node
+from django.template.exceptions import TemplateSyntaxError
+from django.template.loader_tags import construct_relative_path
 from django.utils.safestring import SafeString
 
-from coltrane.renderer import get_html_and_markdown
+from coltrane.renderer import (
+    get_html_and_markdown,
+    render_html_with_django,
+    render_markdown_path,
+)
 from coltrane.retriever import get_content_directory, get_content_paths
 
 
@@ -45,3 +52,58 @@ def directory_contents(context, directory: str = None) -> Dict[str, str]:
             contents.append(metadata)
 
     return contents
+
+
+class IncludeMarkdownNode(Node):
+    """
+    Based on: `django.template.loader_tags.IncludeNode`.
+    """
+
+    context_key = "__include_markdown_context"
+
+    def __init__(self, template, *args, **kwargs):
+        self.template = template
+        super().__init__(*args, **kwargs)
+
+    def render(self, context):
+        """
+        Render the specified template and context.
+        """
+
+        template_name = self.template.resolve(context)
+
+        cache = context.render_context.dicts[0].setdefault(self, {})
+        template = cache.get(template_name)
+
+        if template is None:
+            template = context.template.engine.select_template((template_name,))
+            cache[template_name] = template
+
+        (html, metadata) = render_markdown_path(template.origin.name)
+
+        return render_html_with_django(html, metadata)
+
+
+@register.tag("include_md")
+def do_include_md(parser, token):
+    """
+    Load a markdown template and render it with the current context.
+
+    Based on: `django.template.loader_tags.do_include`.
+
+    Example:
+        {% include "foo/some_include" %}
+    """
+    bits = token.split_contents()
+
+    if len(bits) < 2:
+        raise TemplateSyntaxError(
+            "%r tag takes at least one argument: the name of the template to "
+            "be included." % bits[0]
+        )
+
+    bits[1] = construct_relative_path(parser.origin.template_name, bits[1])
+
+    return IncludeMarkdownNode(
+        parser.compile_filter(bits[1]),
+    )