fix: custom repr implementation for consistency with pprint

django/utils/repr.py

@@ -0,0 +1,13 @@
+import reprlib
+
+
+class DjangoRepr(reprlib.Repr):
+
+    def config(self, limit):
+        """Sets maximum print length for all data structures using the given value"""
+        for attr in dir(self):
+            if attr.startswith("max") and attr != "maxlevel":
+                setattr(self, attr, limit)
+
+    def repr_str(self, x, level):
+        return x[: self.maxstring]

django/views/debug.py

@@ -2,7 +2,6 @@ import functools
 import inspect
 import itertools
 import re
-import reprlib
 import sys
 import types
 import warnings
@@ -18,6 +17,7 @@ from django.utils.datastructures import MultiValueDict
 from django.utils.encoding import force_str
 from django.utils.module_loading import import_string
 from django.utils.regex_helper import _lazy_re_compile
+from django.utils.repr import DjangoRepr
 from django.utils.version import PY311, get_docs_version
 from django.views.decorators.debug import coroutine_functions_to_sensitive_variables
 
@@ -311,16 +311,8 @@ class SafeExceptionReporterFilter:
 class ExceptionReporter:
     """Organize and coordinate reporting on exceptions."""
 
-    repr_instance = reprlib.Repr()
-    repr_instance.indent = 2
-    repr_instance.maxdeque = 4096
-    repr_instance.maxstring = 4096
-    repr_instance.maxlist = 4096
-    repr_instance.maxset = 4096
-    repr_instance.maxdict = 4096
-    repr_instance.maxfrozenset = 4096
-    repr_instance.maxarray = 4096
-    repr_instance.maxother = 4096
+    repr_instance = DjangoRepr()
+    PRINT_LIMIT = 4096
 
     @property
     def html_template_path(self):
@@ -342,6 +334,8 @@ class ExceptionReporter:
         self.template_does_not_exist = False
         self.postmortem = None
 
+        self.repr_instance.config(limit=ExceptionReporter.PRINT_LIMIT)
+
     def _get_raw_insecure_uri(self):
         """
         Return an absolute URI from variables available in this request. Skip
@@ -364,9 +358,22 @@ class ExceptionReporter:
             if "vars" in frame:
                 frame_vars = []
                 for k, v in frame["vars"]:
-                    if isinstance(v, Sized) and len(v) > 4096:
-                        self.repr_instance.fillvalue = "...%d more" % (len(v) - 4096)
-                    v = self.repr_instance.repr(v)
+                    try:
+                        # Check if there are any exceptions in __repr__ fn of the object
+                        v = repr(v)
+
+                        trim_msg = ""
+
+                        if isinstance(v, Sized) and len(v) > 4096:
+                            diff = len(v) - 4096
+                            trim_msg = "...<trimmed %d bytes string>" % diff
+
+                        v = self.repr_instance.repr(v)
+                        v += trim_msg
+
+                    except Exception as e:
+                        v = "Error in formatting: %s: %s" % (e.__class__.__name__, e)
+                    print(v)
                     frame_vars.append((k, v))
                 frame["vars"] = frame_vars
             frames[i] = frame

tests/view_tests/tests/test_debug.py

@@ -1036,15 +1036,20 @@ class ExceptionReporterTests(SimpleTestCase):
 
     def test_local_variable_escaping(self):
         """Safe strings in local variables are escaped."""
+        #  <p>Local variable</p>\
+        # '<p>Local variable</p>'
         try:
             local = mark_safe("<p>Local variable</p>")
+            print("safe string:", repr(local))
             raise ValueError(local)
         except Exception:
             exc_type, exc_value, tb = sys.exc_info()
+
         html = ExceptionReporter(None, exc_type, exc_value, tb).get_traceback_html()
         self.assertIn(
-            '<td class="code"><pre>&#x27;&lt;p&gt;Local variable&lt;/p&gt;&#x27;</pre>'
-            "</td>",
+            #  <td><pre>&lt;p&gt;Local variable&lt;/p&gt;</pre></td>
+            # <td class="code"><pre>&lt;p&gt;Local variable&lt;/p&gt;</pre></td>
+            '<td class="code"><pre>&#x27;&lt;p&gt;Local variable&lt;/p&gt;&#x27;</pre>',
             html,
         )
 
@@ -1066,7 +1071,7 @@ class ExceptionReporterTests(SimpleTestCase):
 
     def test_too_large_values_handling(self):
         "Large values should not create a large HTML."
-        large = 256 * 1024
+        large = 5000
         repr_of_str_adds = len(repr(""))
         try:
 
@@ -1081,9 +1086,10 @@ class ExceptionReporterTests(SimpleTestCase):
         reporter = ExceptionReporter(None, exc_type, exc_value, tb)
         html = reporter.get_traceback_html()
         self.assertEqual(len(html) // 1024 // 128, 0)  # still fit in 128Kb
-        self.assertIn(
-            "&lt;trimmed %d bytes string&gt;" % (large + repr_of_str_adds,), html
+        msg = "&lt;trimmed %d bytes string&gt;" % (
+            large - ExceptionReporter.PRINT_LIMIT + repr_of_str_adds,
         )
+        self.assertIn(msg, html)
 
     def test_encoding_error(self):
         """