Add API endpoint for pattern rendering via POST

Author: thibaudcolas

pattern_library/monkey_utils.py

@@ -3,7 +3,6 @@
 from django.template.library import SimpleNode
 
 from pattern_library.utils import (
-    get_pattern_config,
     is_pattern_library_context,
     render_pattern,
 )
@@ -33,15 +32,15 @@ def node_render(context):
 
                 # Load pattern's config
                 current_template_name = parser.origin.template_name
-                pattern_config = get_pattern_config(current_template_name)
+                tag_overrides = context.get("__pattern_library_tag_overrides", {})
 
                 # Extract values for lookup from the token
                 bits = token.split_contents()
                 tag_name = bits[0]
                 arguments = " ".join(bits[1:]).strip()
 
                 # Get config for a specific tag
-                tag_config = pattern_config.get("tags", {}).get(tag_name, {})
+                tag_config = tag_overrides.get(tag_name, {})
                 if tag_config:
                     # Get config for specific arguments
                     tag_config = tag_config.get(arguments, {})

pattern_library/urls.py

@@ -1,4 +1,4 @@
-from django.urls import re_path
+from django.urls import re_path, path
 
 from pattern_library import get_pattern_template_suffix, views
 
@@ -19,4 +19,7 @@
         views.RenderPatternView.as_view(),
         name="render_pattern",
     ),
+
+    # API rendering
+    path('api/v1/render-pattern', views.render_pattern_api, name='render_pattern_api'),
 ]

pattern_library/utils.py

@@ -210,12 +210,18 @@ def get_pattern_markdown(template_name):
         return markdown.markdown(f.read())
 
 
-def render_pattern(request, template_name, allow_non_patterns=False):
+def render_pattern(request, template_name, allow_non_patterns=False, config=None):
     if not allow_non_patterns and not is_pattern(template_name):
         raise TemplateIsNotPattern
 
-    context = get_pattern_context(template_name)
+    if not config:
+        config = get_pattern_config(template_name)
+
+    context = config.get('context', {})
+    tags = config.get('tags', {})
+    mark_context_strings_safe(context)
     context[get_pattern_context_var_name()] = True
+    context['__pattern_library_tag_overrides'] = tags
     for modifier in registry.get_for_template(template_name):
         modifier(context=context, request=request)
     return render_to_string(template_name, request=request, context=context)

pattern_library/views.py

@@ -1,9 +1,12 @@
+import json
+
 from django.http import Http404, HttpResponse
 from django.template.loader import get_template
 from django.utils.decorators import method_decorator
 from django.utils.html import escape
 from django.views.decorators.clickjacking import xframe_options_sameorigin
-from django.views.generic.base import TemplateView
+from django.views.decorators.csrf import csrf_exempt
+from django.views.generic.base import TemplateView, View
 
 from pattern_library import get_base_template_names, get_pattern_base_template_name
 from pattern_library.exceptions import PatternLibraryEmpty, TemplateIsNotPattern
@@ -99,3 +102,17 @@ def get(self, request, pattern_template_name=None):
             return self.render_to_response(context)
 
         return HttpResponse(rendered_pattern)
+
+
+@csrf_exempt
+def render_pattern_api(request):
+    data = json.loads(request.body.decode("utf-8"))
+    template_name = data["template_name"]
+    config = data["config"]
+
+    try:
+        rendered_pattern = render_pattern(request, template_name, allow_non_patterns=False, config=config)
+    except TemplateIsNotPattern:
+        raise Http404
+
+    return HttpResponse(rendered_pattern)

tests/templates/patterns/molecules/button/button.html

@@ -0,0 +1,4 @@
+{% load test_tags %}
+<a href="{% if target_url %}{{ target_url }}{% else %}{% pageurl target_page %}{% endif %}" class="button">
+    {% if label %}{{ label }}{% else %}{{ target_page.title }}{% endif %}
+</a>

tests/templates/patterns/molecules/button/button.yaml

@@ -0,0 +1,7 @@
+context:
+  target_page:
+    title: Get started
+tags:
+  pageurl:
+    target_page:
+      raw: /get-started

tests/templatetags/test_tags.py

@@ -27,6 +27,12 @@ def default_html_tag_falsey(arg=None):
     raise Exception("default_tag raised an exception")
 
 
+@register.simple_tag()
+def pageurl(page):
+    """Approximation of wagtail built-in tag for realistic example."""
+    return "/page/url"
+
+
 # Get widget type of a field
 @register.filter(name="widget_type")
 def widget_type(bound_field):
@@ -36,3 +42,4 @@ def widget_type(bound_field):
 override_tag(register, "error_tag")
 override_tag(register, "default_html_tag", default_html="https://potato.com")
 override_tag(register, "default_html_tag_falsey", default_html=None)
+override_tag(register, "pageurl")