app_filters.py: Use Django to load template.

This commit allows us to load template using Django in
render_markdown_path.

zerver/templatetags/app_filters.py

@@ -1,5 +1,7 @@
+from typing import Dict, Optional, Any
+
 from django.conf import settings
-from django.template import Library
+from django.template import Library, loader
 from django.utils.safestring import mark_safe
 from django.utils.lru_cache import lru_cache
 
@@ -78,6 +80,7 @@ def render_markdown_path(markdown_file_path):
     md_engine = markdown.Markdown(extensions=md_extensions)
     md_engine.reset()
 
-    markdown_string = force_text(open(markdown_file_path).read())
+    template = loader.get_template(markdown_file_path)
+    markdown_string = template.render()
     html = md_engine.convert(markdown_string)
     return mark_safe(html)

zerver/tests/test_templates.py

@@ -158,7 +158,7 @@ class TemplateTestCase(ZulipTestCase):
         user_profile = get_user_profile_by_email(email)
 
         context = dict(
-            article="templates/zerver/help/index.md",
+            article="zerver/help/index.md",
             shallow_tested=True,
             user_profile=user_profile,
             user=user_profile,

zerver/views/integrations.py

@@ -4,6 +4,7 @@ from collections import OrderedDict
 from django.views.generic import TemplateView
 from django.conf import settings
 from django.http import HttpRequest, HttpResponse, HttpResponseNotFound
+from django.template import loader
 from django.shortcuts import render
 
 import os
@@ -49,7 +50,7 @@ class APIView(ApiURLView):
 
 class HelpView(ApiURLView):
     template_name = 'zerver/help/main.html'
-    path_template = os.path.join(settings.DEPLOY_ROOT, 'templates/zerver/help/%s.md')
+    path_template = 'zerver/help/%s.md'
 
     def get_path(self, article):
         # type: (str) -> str
@@ -62,10 +63,12 @@ class HelpView(ApiURLView):
         article = kwargs["article"]
         context = super(HelpView, self).get_context_data()  # type: Dict[str, Any]
         path = self.get_path(article)
-        if os.path.exists(path):
+        try:
+            loader.get_template(path)
             context["article"] = path
-        else:
+        except loader.TemplateDoesNotExist:
             context["article"] = self.get_path("missing")
+
         # For disabling the "Back to home" on the homepage
         context["not_index_page"] = not path.endswith("/index.md")
         return context
@@ -74,7 +77,9 @@ class HelpView(ApiURLView):
         # type: (HttpRequest, str) -> HttpResponse
         path = self.get_path(article)
         result = super(HelpView, self).get(self, article=article)
-        if not os.path.exists(path):
+        try:
+            loader.get_template(path)
+        except loader.TemplateDoesNotExist:
             # Ensure a 404 response code if no such document
             result.status_code = 404
         return result