Add missing import, initialize missing variable (PR #132)

- The exceptions module was used but not imported.
- The next_validator variable was not initialized in a certain code path, resulting in UnboundLocalErrors

---------

Co-authored-by: Bharat Chauhan <tell.bhch@gmail.com>

django_jsonform/models/compat.py

@@ -33,6 +33,7 @@
 
 import json
 from django.db import models
+from django.core import exceptions
 from django_jsonform.forms.fields import JSONFormField
 
 
@@ -95,4 +96,3 @@ def formfield(self, **kwargs):
             'decoder': self.decoder,
             **kwargs,
         })
-

django_jsonform/validators.py

@@ -172,7 +172,7 @@ def validate_array(self, schema, data, coords, *, raise_exc=False):
                 # TypeError is raised when trying to make a set from unashable types
                 # i.e. lists and dicts
                 # so we JSON-ify each item to make it a string
-                if len(data) != len(set([json.dumps(item) for item in data])): 
+                if len(data) != len(set([json.dumps(item) for item in data])):
                     self.add_error(coords, 'All items in this list must be unique.', raise_exc=raise_exc)
 
         if choices:
@@ -188,6 +188,7 @@ def validate_array(self, schema, data, coords, *, raise_exc=False):
             next_schema = self.get_ref(next_schema['$ref'])
 
         next_type = get_schema_type(next_schema)
+        next_validator = None
 
         if next_type is None:
             # property type isn't provided
@@ -261,6 +262,7 @@ def validate_object(self, schema, data, coords, raise_exc=False):
                     next_schema['required'] = True
 
             next_type = get_schema_type(next_schema)
+            next_validator = None
 
             if next_type is None:
                 # property type isn't provided
@@ -335,7 +337,7 @@ def validate_string(self, schema, data, coords, raise_exc=False):
             elif format_ == 'date-time':
                 if not self.get_datetime(data):
                     self.add_error(coords, 'Enter a valid date and time.', raise_exc=raise_exc)
- 
+
     def validate_boolean(self, schema, data, coords, raise_exc=False):
         if schema.get('required') and data is None:
             self.add_error(coords, 'This field is required.', raise_exc=raise_exc)
@@ -429,7 +431,7 @@ def validate_oneOf(self, schema, data, coords, raise_exc=False):
                     matches_found += 1
                     # if matches_found > 1:
                     #    break
-                    # 
+                    #
                     # TODO: validate that one and only one subschema matches
                     # currently it's a bit hard to do, so we'll just match
                     # one item and don't care wheter more than one match