Merge pull request #71 from janheini/hash-static-files

Invalidate HTTP cache by appending md5sum to static files

Author: SmithChart

flamingo/core/plugins/static.py

@@ -1,20 +1,69 @@
+import hashlib
 import os
 
 
 class Static:
+    def _iter_static_files(self, context):
+        for static_dir in context.templating_engine.find_static_dirs():
+            for dirpath, _dirnames, filenames in os.walk(static_dir):
+                for filename in filenames:
+                    yield (static_dir, dirpath, filename)
+
+    def templating_engine_setup(self, context, templating_engine):
+        """Add a Jinja2 filter that appends md5sum to static files as a query parameter
+
+        Adding the checksum as a query parameter invalidates any HTTP caching when the file
+        contents change.
+
+        Usage Example:
+        <link rel="stylesheet" href="{{ static_file('theme/static/css/style.css') }}" type="text/css" />
+
+        Will be rendered as
+        <link rel="stylesheet" href="/static/css/style.css?<md5sum>" type="text/css" />
+        """
+
+        self.static_files_map = {}
+
+        for static_dir, dirpath, filename in self._iter_static_files(context):
+            source = os.path.join(dirpath, filename)
+
+            href = os.path.join(
+                "/",
+                os.path.relpath(
+                    context.settings.STATIC_ROOT,
+                    context.settings.OUTPUT_ROOT,
+                ),
+                os.path.relpath(dirpath, static_dir),
+                filename,
+            )
+
+            with open(source, "rb") as file:
+                md5 = hashlib.file_digest(file, hashlib.md5).hexdigest()
+
+            self.static_files_map[source] = {
+                "href": href,
+                "md5": md5,
+            }
+
+        def static_file(source: str):
+            return "?".join(
+                (
+                    self.static_files_map[source]["href"],
+                    self.static_files_map[source]["md5"],
+                )
+            )
+
+        templating_engine.env.globals["static_file"] = static_file
+
     def post_build(self, context):
         if context.settings.CONTENT_PATHS:
             return
 
-        for static_dir in context.templating_engine.find_static_dirs():
-            for root, _dirs, files in os.walk(static_dir):
-                for f in files:
-                    source = os.path.join(root, f)
-
-                    destination = os.path.join(
-                        context.settings.STATIC_ROOT,
-                        os.path.relpath(root, static_dir),
-                        f,
-                    )
-
-                    context.cp(source=source, destination=destination)
+        for static_dir, dirpath, filename in self._iter_static_files(context):
+            source = os.path.join(dirpath, filename)
+            destination = os.path.join(
+                context.settings.STATIC_ROOT,
+                os.path.relpath(dirpath, static_dir),
+                filename,
+            )
+            context.cp(source=source, destination=destination)