Move header value creation into the panels.

This moves more logic into the Panel class and gives
greater control to the Panel subclasses on how things should
work.

Author: tim-schilling

debug_toolbar/middleware.py

@@ -71,7 +71,8 @@ def __call__(self, request):
         # included in the response.
         rendered = toolbar.render_toolbar()
 
-        response = self.generate_headers(request, response, toolbar.enabled_panels)
+        for header, value in self.get_headers(request, toolbar.enabled_panels).items():
+            response.headers[header] = value
 
         # Check for responses where the toolbar can't be inserted.
         content_encoding = response.get("Content-Encoding", "")
@@ -96,24 +97,12 @@ def __call__(self, request):
         return response
 
     @staticmethod
-    def generate_headers(request, response, panels):
-        stats_data = []
-
+    def get_headers(request, panels):
+        headers = {}
         for panel in panels:
-            response = panel.generate_headers(request, response)
-            stats = panel.get_server_timing_stats()
-            if not stats:
-                continue
-
-            for key, record in stats.items():
-                # example: `SQLPanel_sql_time;dur=0;desc="SQL 0 queries"`
-                stats_data.append(
-                    '{}_{};dur={};desc="{}"'.format(
-                        panel.panel_id, key, record.get("value"), record.get("title")
-                    )
-                )
-
-        if stats_data:
-            response.headers["Server-Timing"] = ", ".join(stats_data)
-
-        return response
+            for header, value in panel.get_headers(request).items():
+                if header in headers:
+                    headers[header] += f", {value}"
+                else:
+                    headers[header] = value
+        return headers

debug_toolbar/panels/__init__.py

@@ -192,14 +192,31 @@ def process_request(self, request):
         """
         return self.get_response(request)
 
-    def generate_headers(self, request, response):
+    def get_headers(self, request):
         """
-        Attach headers to response.
+        Get headers the panel needs to set.
 
-        Call after procssing the request, gives the panel an opportunity to
-        add headers to the outgoing response
-        """
-        return response
+        Called after :meth:`process_request
+        <debug_toolbar.panels.Panel.generate_stats>` and
+        :meth:`process_request<debug_toolbar.panels.Panel.generate_stats>`
+
+        Header values will be appended if multiple panels need to set it.
+
+        By default it sets the Server-Timing header.
+
+        Return dict of headers to be appended.
+        """
+        headers = {}
+        stats = self.get_server_timing_stats()
+        if stats:
+            headers["Server-Timing"] = ", ".join(
+                # example: `SQLPanel_sql_time;dur=0;desc="SQL 0 queries"`
+                '{}_{};dur={};desc="{}"'.format(
+                    self.panel_id, key, record.get("value"), record.get("title")
+                )
+                for key, record in stats.items()
+            )
+        return headers
 
     def generate_stats(self, request, response):
         """

debug_toolbar/panels/history/panel.py

@@ -21,12 +21,13 @@ class HistoryPanel(Panel):
     nav_title = _("History")
     template = "debug_toolbar/panels/history.html"
 
-    def generate_headers(self, request, response):
+    def get_headers(self, request):
+        headers = super().get_headers(request)
         observe_request = get_observe_request()
         store_id = getattr(self.toolbar, "store_id")
         if store_id and observe_request(request):
-            response.headers["DJDT-STORE-ID"] = store_id
-        return response
+            headers["DJDT-STORE-ID"] = store_id
+        return headers
 
     @property
     def enabled(self):

docs/panels.rst

@@ -386,6 +386,8 @@ unauthorized access. There is no public CSS API at this time.
 
     .. automethod:: debug_toolbar.panels.Panel.generate_stats
 
+    .. automethod:: debug_toolbar.panels.Panel.get_headers
+
     .. automethod:: debug_toolbar.panels.Panel.run_checks
 
 .. _javascript-api: