PyCharm debugger breaks django form validation (PY-14578)

Create a separate resolver for Django forms in order to prevent calling self.errors because it is a property and has side effects. Also We shouldn't call str(), because it also has side effects.

python/helpers/pydev/_pydevd_bundle/pydevd_resolver.py

@@ -100,9 +100,9 @@ class DefaultResolver:
     def resolve(self, var, attribute):
         return getattr(var, attribute)
 
-    def get_dictionary(self, var):
+    def get_dictionary(self, var, names=None):
         if MethodWrapperType:
-            return self._getPyDictionary(var)
+            return self._getPyDictionary(var, names)
         else:
             return self._getJyDictionary(var)
 
@@ -162,15 +162,20 @@ class DefaultResolver:
 
         return ret
 
-    def _getPyDictionary(self, var):
+    def get_names(self, var):
+        names = dir(var)
+        if not names and hasattr(var, '__members__'):
+            names = var.__members__
+        return names
+
+    def _getPyDictionary(self, var, names=None):
         filterPrivate = False
         filterSpecial = True
         filterFunction = True
         filterBuiltIn = True
 
-        names = dir(var)
-        if not names and hasattr(var, '__members__'):
-            names = var.__members__
+        if not names:
+            names = self.get_names(var)
         d = {}
 
         #Be aware that the order in which the filters are applied attempts to
@@ -482,21 +487,34 @@ class MultiValueDictResolver(DictResolver):
 
         raise UnableToResolveVariableException()
 
-    def get_dictionary(self, dict):
-        ret = {}
-        i = 0
-        for key in dict_keys(dict):
-            val = dict.getlist(key)
-            i += 1
-            #we need to add the id because otherwise we cannot find the real object to get its contents later on.
-            key = '%s (%s)' % (self.key_to_str(key), id(key))
-            ret[key] = val
-            if i > MAX_ITEMS_TO_HANDLE:
-                ret[TOO_LARGE_ATTR] = TOO_LARGE_MSG
-                break
 
-        ret['__len__'] = len(dict)
-        return ret
+
+#=======================================================================================================================
+# DjangoFormResolver
+#=======================================================================================================================
+class DjangoFormResolver(DefaultResolver):
+    has_errors_attr = False
+
+    def get_names(self, var):
+        names = dir(var)
+        if not names and hasattr(var, '__members__'):
+            names = var.__members__
+
+        if "errors" in names:
+            self.has_errors_attr = True
+            names.remove("errors")
+        return names
+
+    def get_dictionary(self, var, names=None):
+        # Do not call self.errors because it is property and has side effects
+        d = defaultResolver.get_dictionary(var, self.get_names(var))
+        if self.has_errors_attr:
+            try:
+                errors_attr = getattr(var, "_errors")
+            except:
+                errors_attr = None
+            d["errors"] = errors_attr
+        return d
 
 
 #=======================================================================================================================
@@ -567,5 +585,6 @@ jyArrayResolver = JyArrayResolver()
 setResolver = SetResolver()
 ndarrayResolver = NdArrayResolver()
 multiValueDictResolver = MultiValueDictResolver()
+djangoFormResolver = DjangoFormResolver()
 dequeResolver = DequeResolver()
 frameResolver = FrameResolver()

python/helpers/pydev/_pydevd_bundle/pydevd_xml.py

@@ -81,6 +81,13 @@ def _update_type_map():
         except:
             pass  #django may not be installed
 
+        try:
+            from django.forms import BaseForm
+            _TYPE_MAP.insert(0, (BaseForm, pydevd_resolver.djangoFormResolver))
+            #we should put it before instance resolver
+        except:
+            pass  #django may not be installed
+
         try:
             from collections import deque
             _TYPE_MAP.append((deque, pydevd_resolver.dequeResolver))
@@ -181,6 +188,11 @@ def var_to_xml(val, name, doTrim=True, additionalInXml=''):
 
     _type, typeName, resolver = get_type(v)
 
+    do_not_call_value_str = False
+    if isinstance(resolver, pydevd_resolver.djangoFormResolver.__class__):
+        # do not call str() of Django form objects because has side effects and breaks self.errors
+        do_not_call_value_str = True
+
     try:
         if hasattr(v, '__class__'):
             if v.__class__ == frame_type:
@@ -204,7 +216,11 @@ def var_to_xml(val, name, doTrim=True, additionalInXml=''):
                         cName = cName[:-2]
                 except:
                     cName = str(v.__class__)
-                value = '%s: %s' % (cName, v)
+
+                if do_not_call_value_str:
+                    value = '%s: %r' % (cName, v)
+                else:
+                    value = '%s: %s' % (cName, v)
         else:
             value = str(v)
     except: