[refs #28] Initial attempts at better python3 support

pylint_django/checkers/models.py

@@ -5,24 +5,28 @@
 from pylint.checkers.utils import check_messages
 from pylint.checkers import BaseChecker
 from pylint_django.__pkginfo__ import BASE_ID
-from pylint_django.utils import node_is_subclass, PY3
+from pylint_django.utils import node_is_subclass, PY3, iter_cls_and_bases
 
 
+REPR_NAME = '__str__' if PY3 else '__unicode__'
+
 MESSAGES = {
-    'E%d01' % BASE_ID: ("__unicode__ on a model must be callable (%s)",
+    'E%d01' % BASE_ID: ("%s on a model must be callable (%%s)" % REPR_NAME,
                         'model-unicode-not-callable',
-                        "Django models require a callable __unicode__ method"),
-    'W%d01' % BASE_ID: ("No __unicode__ method on model (%s)",
+                        "Django models require a callable %s method" % REPR_NAME),
+    'W%d01' % BASE_ID: ("No %s method on model (%%s)" % REPR_NAME,
                         'model-missing-unicode',
-                        "Django models should implement a __unicode__ method for string representation"),
+                        "Django models should implement a %s "
+                        "method for string representation" % REPR_NAME),
     'W%d02' % BASE_ID: ("Found __unicode__ method on model (%s). Python3 uses __str__.",
                         'model-has-unicode',
                         "Django models should not implement a __unicode__ "
                         "method for string representation when using Python3"),
-    'W%d03' % BASE_ID: ("Model does not explicitly define __unicode__ (%s)",
+    'W%d03' % BASE_ID: ("Model does not explicitly define %s (%%s)" % REPR_NAME,
                         'model-no-explicit-unicode',
-                        "Django models should implement a __unicode__ method for string representation. "
-                        "A parent class of this model does, but ideally all models should be explicit.")
+                        "Django models should implement a %s method for string representation. "
+                        "A parent class of this model does, but ideally all models should be "
+                        "explicit." % REPR_NAME)
 }
 
 
@@ -54,10 +58,22 @@ class ModelChecker(BaseChecker):
     @check_messages('model-missing-unicode')
     def visit_class(self, node):
         """Class visitor."""
+
         if not node_is_subclass(node, 'django.db.models.base.Model'):
             # we only care about models
             return
 
+        has_py2_compat_decorator = False
+        for cur_node in iter_cls_and_bases(node):
+            if cur_node.qname() == 'django.db.models.base.Model':
+                break
+            if cur_node.decorators is not None:
+                for decorator in cur_node.decorators.nodes:
+                    print decorator
+                    if getattr(decorator, 'name', None) == 'python_2_unicode_compatible':
+                        has_py2_compat_decorator = True
+                        break
+
         for child in node.get_children():
             if _is_meta_with_abstract(child):
                 return
@@ -69,7 +85,7 @@ def visit_class(self, node):
                     continue
 
                 name = grandchildren[0].name
-                if name != '__unicode__':
+                if name != REPR_NAME:
                     continue
 
                 assigned = grandchildren[1].infered()[0]
@@ -79,28 +95,20 @@ def visit_class(self, node):
                 self.add_message('E%s01' % BASE_ID, args=node.name, node=node)
                 return
 
-            if isinstance(child, Function) and child.name == '__unicode__':
-                if PY3:
+            if isinstance(child, Function) and child.name == REPR_NAME:
+                if PY3 and not has_py2_compat_decorator:
                     self.add_message('W%s02' % BASE_ID, args=node.name, node=node)
                 return
 
-        # if we get here, then we have no __unicode__ method directly on the class itself
-        if PY3:
-            return
-
         # a different warning is emitted if a parent declares __unicode__
         for method in node.methods():
-            if method.name == '__unicode__':
+            if method.name == REPR_NAME:
                 # this happens if a parent declares the unicode method but
                 # this node does not
                 self.add_message('W%s03' % BASE_ID, args=node.name, node=node)
                 return
 
         # if the Django compatibility decorator is used then we don't emit a warning
         # see https://github.com/landscapeio/pylint-django/issues/10
-        if node.decorators is not None:
-            for decorator in node.decorators.nodes:
-                if getattr(decorator, 'name', None) == 'python_2_unicode_compatible':
-                    return
-
-        self.add_message('W%s01' % BASE_ID, args=node.name, node=node)
+        if not has_py2_compat_decorator:
+            self.add_message('W%s01' % BASE_ID, args=node.name, node=node)

pylint_django/utils.py

@@ -29,3 +29,17 @@ def node_is_subclass(cls, subclass_name):
             continue
 
     return False
+
+
+def iter_cls_and_bases(cls):
+    yield cls
+    if cls.bases == YES:
+        return
+
+    for base_cls in cls.bases:
+        try:
+            for inf in base_cls.infered():
+                for yielded in iter_cls_and_bases(inf):
+                    yield yielded
+        except InferenceError:
+            continue

test/input/func_noerror_model_unicode_callable_py33.py

@@ -0,0 +1,15 @@
+"""
+Ensures that django models without a __unicode__ method are flagged
+"""
+#  pylint: disable=C0111
+
+from django.db import models
+
+
+def external_unicode_func(model):
+    return model.something
+
+
+class SomeModel(models.Model):
+    something = models.CharField(max_length=255)
+    __str__ = external_unicode_func

test/input/func_noerror_model_unicode_lambda_py33.py

@@ -0,0 +1,11 @@
+"""
+Ensures that django models without a __unicode__ method are flagged
+"""
+#  pylint: disable=C0111
+
+from django.db import models
+
+
+class SomeModel(models.Model):
+    something = models.CharField(max_length=255)
+    __str__ = lambda s: str(s.something)

test/input/func_noerror_models_py33.py

@@ -25,6 +25,9 @@ def stuff(self):
 
         print(self.get_some_field_display())
 
+    def __str__(self):
+        print 'some model %s' % self.id
+
 
 class SubclassModel(SomeModel):
     class Meta:

test/input/func_noerror_unicode_py2_compatible.py → test/input/func_unicode_py2_compatible_py_28.py

@@ -15,3 +15,7 @@ class ModelName(models.Model):
 
     def __str__(self):
         return self.name
+
+
+class ModelSubclass(ModelName):
+    count = models.IntegerField()

test/messages/func_unicode_py2_compatible_py_28.txt

@@ -0,0 +1 @@
+W: 20:ModelSubclass: Model does not explicitly define __unicode__ (ModelSubclass)