PR for Issue 728

jsonschema/exceptions.py

@@ -283,6 +283,46 @@ def total_errors(self):
         child_errors = sum(len(tree) for _, tree in self._contents.items())
         return len(self.errors) + child_errors
 
+def get_instance_type(value):
+    """
+    Returns the type to use in type comparaisons of values' types
+
+    Arguments:
+        value (object):
+            an object from the schema or the instance
+
+    Returns (type):
+        the type of the object passed consistent with other JSON types
+    """
+    value_type = type(value)
+    if value_type in [int, float]:
+        return float
+    elif value_type in [bool, str, list, dict]:
+        return value_type
+    return None
+
+def get_schema_type(value):
+    """
+    Returns the type of the validation rule as a python type
+
+    Arguments:
+        value (string):
+            One of the values : ['string', 'array', 'object', 'number', None]
+
+    Returns (type):
+        One of the values : [str, list, dict, float, None]
+    """
+    if value == 'string':
+        return str
+    elif value == 'number':
+        return float
+    elif value == 'object':
+        return dict
+    elif value == 'array':
+        return list
+    else:
+        return None
+
 
 def by_relevance(weak=WEAK_MATCHES, strong=STRONG_MATCHES):
     """
@@ -301,8 +341,31 @@ def by_relevance(weak=WEAK_MATCHES, strong=STRONG_MATCHES):
             a collection of validator names to consider to be "strong"
     """
     def relevance(error):
-        validator = error.validator
-        return -len(error.path), validator not in weak, validator in strong
+        same_type = False
+        # If the 'type' property has been provided within the schema rule
+        # set rule_type to the python <class 'type'> corresponding
+        if isinstance(error.schema, dict) and 'type' in error.schema:
+            rule_type = get_schema_type(error.schema['type'])
+        else:
+            rule_type = None
+
+        instance = error.instance
+        instance_type = None
+        instance_type = get_instance_type(instance)
+
+        if rule_type is not None:
+            same_type = instance_type == rule_type
+        elif error.validator == 'enum':
+            if isinstance(error.validator_value, list):
+                for value in error.validator_value:
+                    same_type = get_instance_type(value) == instance_type
+                    if same_type:
+                        break
+        elif error.validator == 'const':
+            same_type = get_instance_type(error.validator_value) == instance_type
+
+        return -len(error.path), error.validator not in weak, error.validator in strong, -same_type
+
     return relevance
 
 

jsonschema/tests/test_exceptions.py

@@ -1,7 +1,7 @@
 from unittest import TestCase
 import textwrap
 
-from jsonschema import Draft4Validator, exceptions
+from jsonschema import Draft4Validator, Draft7Validator, exceptions
 
 
 class TestBestMatch(TestCase):
@@ -154,6 +154,87 @@ def test_no_errors(self):
         validator = Draft4Validator({})
         self.assertIsNone(exceptions.best_match(validator.iter_errors({})))
 
+    def test_same_type_is_prioritized(self):
+        # Best match to prioritize error with the same type as value regardless of order
+        validator = Draft7Validator({
+            "properties" : {
+                "value" : {
+                    "anyOf" : [
+                        {"type" : "array" , "minItems" : 2},
+                        {"type" : "string", "minLength" : 10},
+                        ],
+                    },
+                },
+            },
+        )
+        self.assertEqual(exceptions.best_match(validator.iter_errors({"value" : "foo"})).validator, "minLength")
+
+        validator = Draft7Validator({
+            "properties" : {
+                "value" : {
+                    "anyOf" : [
+                        {"type" : "string", "minLength" : 10},
+                        {"type" : "array" , "minItems" : 2},
+                        ],
+                    },
+                },
+            },
+        )
+        self.assertEqual(exceptions.best_match(validator.iter_errors({"value" : "foo"})).validator, "minLength")
+
+    def test_same_type_is_prioritized_const(self):
+        validator = Draft7Validator({
+            "properties" : {
+                "value" : {
+                    "anyOf" : [
+                        {"type" : "array" , "minItems" : 2},
+                        {"const" : "bar"},
+                        ],
+                    },
+                },
+            },
+        )
+        self.assertEqual(exceptions.best_match(validator.iter_errors({"value" : "foo"})).validator, "const")
+
+        validator = Draft7Validator({
+            "properties" : {
+                "value" : {
+                    "anyOf" : [
+                        {"const" : "bar"},
+                        {"type" : "array" , "minItems" : 2},
+                        ],
+                    },
+                },
+            },
+        )
+        self.assertEqual(exceptions.best_match(validator.iter_errors({"value" : "foo"})).validator, "const")
+
+    def test_same_type_is_prioritized_enum(self):
+        validator = Draft7Validator({
+            "properties" : {
+                "value" : {
+                    "anyOf" : [
+                        {"type" : "array" , "minItems" : 2},
+                        {"enum" : ["bar", 2.3]},
+                        ],
+                    },
+                },
+            },
+        )
+        self.assertEqual(exceptions.best_match(validator.iter_errors({"value" : "foo"})).validator, "enum")
+
+        validator = Draft7Validator({
+            "properties" : {
+                "value" : {
+                    "anyOf" : [
+                        {"enum" : ["bar", 2.3]},
+                        {"type" : "array" , "minItems" : 2},
+                        ],
+                    },
+                },
+            },
+        )
+        self.assertEqual(exceptions.best_match(validator.iter_errors({"value" : "foo"})).validator, "enum")
 
 class TestByRelevance(TestCase):
     def test_short_paths_are_better_matches(self):