Fixes for python3 (#28)

* Fixes for Python 3
* Disable flake8 rules for backslashes and single-letter class name

Signed-off-by: Dan Davison <dandavison7@gmail.com>

modeltree/tree.py

@@ -1,6 +1,7 @@
 import inspect
 import warnings
 
+import six
 from django.apps import apps
 from django.db import models
 from django.conf import settings
@@ -37,6 +38,7 @@ class ModelNotRelated(ModelLookupError):
     pass
 
 
+@six.python_2_unicode_compatible
 class ModelTreeNode(object):
     def __init__(self, model, parent=None, relation=None, reverse=None,
                  related_name=None, accessor_name=None, nullable=False,
@@ -99,9 +101,6 @@ def __str__(self):
 
         return name
 
-    def __unicode__(self):
-        return unicode(str(self))
-
     def __repr__(self):
         return '<{0}>'.format(self)
 
@@ -244,7 +243,7 @@ class ModelTree(object):
         An excluded route is more obvious: joining from the specified source
         model to the specified target model is not allowed.
 
-    """
+    """                                                           # noqa: W605
     def __init__(self, model=None, **kwargs):
         if model is None and 'root_model' in kwargs:
             warnings.warn('The "root_model" key has been renamed to "model"',
@@ -572,7 +571,7 @@ def _find_relations(self, node, depth=0):
         # NOTE: the many-to-many relations are evaluated first to prevent
         # 'through' models being bound as a ForeignKey relationship.
         fields = sorted(model._meta.get_fields(), reverse=True,
-                        key=lambda f: f.many_to_many)
+                        key=lambda f: bool(f.many_to_many))
 
         # determine relational fields to determine paths
         forward_fields = [
@@ -824,7 +823,7 @@ def _get_or_create(self, alias=None, **kwargs):
             alias = MODELTREE_DEFAULT_ALIAS
 
         # Qualified app.model label
-        elif isinstance(alias, basestring) and '.' in alias:
+        elif isinstance(alias, six.string_types) and '.' in alias:
             app_name, model_name = alias.split('.', 1)
             model = apps.get_model(app_name, model_name)
 

modeltree/utils.py

@@ -161,7 +161,7 @@ def __init__(self, tree=None, *args, **kwargs):
             nargs.append(key)
 
         # iterate over each kwarg and perform the conversion
-        for key, value in kwargs.iteritems():
+        for key, value in kwargs.items():
             lookup = resolve_lookup(key, tree=tree)
             nkwargs[lookup] = value
 

setup.py

@@ -12,7 +12,7 @@
     'include_package_data': True,
 
     # Dependencies
-    'install_requires': ['django>=1.8,<=1.11'],
+    'install_requires': ['django>=1.8,<=1.11', 'six>=1.11'],
 
     'test_suite': 'test_suite',
 

tests/models.py

@@ -43,13 +43,13 @@ class Meeting(models.Model):
 # Router Test Models.. no relation to the above models
 # The raw model tree looks like this:
 #        A
-#       / \
+#       / \                                                       # noqa: W605
 #      C   B
-#      |  / \
+#      |  / \                                                     # noqa: W605
 #       D    G
-#      / \   |
+#      / \   |                                                    # noqa: W605
 #     E   F  |
-#      \ / \ |
+#      \ / \ |                                                    # noqa: W605
 #       J   H
 #       |   |
 #       K   I
@@ -89,7 +89,7 @@ class H(models.Model):
     f = models.ForeignKey(F)
 
 
-class I(models.Model):
+class I(models.Model):                                            # noqa: E742
     i = models.ManyToManyField(H)
 
 

tox.ini

@@ -4,7 +4,7 @@ filename = *.py
 
 [tox]
 envlist =
-    clean,py27-django{18,19,110,111},stats
+    clean,py{27,37}-django{18,19,110,111},stats
 
 [testenv]
 basepython = python2.7
@@ -15,6 +15,7 @@ deps =
     django19: Django==1.9.13
     django110: Django==1.10.7
     django111: Django==1.11.3
+    six == 1.11.0
 commands = {envbindir}/coverage run -p --omit="*tests*" --source=modeltree --branch test_suite.py
 
 [testenv:clean]