panels(templates): avoid evaluating LazyObject

LazyObject is typically used for something expensive to evaluate, so avoid evaluating it just for showing it in the debug toolbar.

Author: nijel

debug_toolbar/panels/templates/panel.py

@@ -96,10 +96,15 @@ def _store_template_info(self, sender, **kwargs):
                 if pformatted is None:
                     temp_layer = {}
                     for key, value in context_layer.items():
+                        # Do not force evaluating LazyObject
+                        if hasattr(value, "_wrapped"):
+                            # SimpleLazyObject has __repr__ which includes actual value
+                            # if it has been already evaluated
+                            temp_layer[key] = repr(value)
                         # Replace any request elements - they have a large
                         # Unicode representation and the request data is
                         # already made available from the Request panel.
-                        if isinstance(value, http.HttpRequest):
+                        elif isinstance(value, http.HttpRequest):
                             temp_layer[key] = "<<request>>"
                         # Replace the debugging sql_queries element. The SQL
                         # data is already made available from the SQL panel.