Support for oneOf composition

Fixes pipermerriam#131

flex/utils.py

@@ -199,3 +199,15 @@ def dereference_reference(reference, context):
             MESSAGES['reference']['unsupported'].format(reference),
         )
     return jsonpointer.resolve_pointer(context, parts.fragment)
+
+
+def exactly_one(iterable):
+    """
+    Returns True if bool(x) is True for exactly one x in the iterable
+    If the iterable is empty, returns False
+    """
+    it = iter(iterable)
+    # check that one is True, then check that none is True in rest of the
+    # iterator
+    return any(it) and not any(it)
+

flex/validation/common.py

@@ -27,6 +27,7 @@
     chain_reduce_partial,
     cast_value_to_type,
     deep_equal,
+    exactly_one
 )
 from flex.paths import (
     match_path_to_api_path,
@@ -299,7 +300,7 @@ def generate_enum_validator(enum, **kwargs):
 
 
 @skip_if_empty
-def validate_allof_anyof(value, sub_schemas, context, method, **kwargs):
+def validate_allof_anyof_oneof(value, sub_schemas, context, method, **kwargs):
     from flex.validation.schema import (
         construct_schema_validators,
     )
@@ -323,11 +324,15 @@ def validate_allof_anyof(value, sub_schemas, context, method, **kwargs):
 
 
 def generate_allof_validator(allOf, context, **kwargs):
-    return functools.partial(validate_allof_anyof, sub_schemas=allOf, context=context, method=all)
+    return functools.partial(validate_allof_anyof_oneof, sub_schemas=allOf, context=context, method=all)
 
 
 def generate_anyof_validator(anyOf, context, **kwargs):
-    return functools.partial(validate_allof_anyof, sub_schemas=anyOf, context=context, method=any)
+    return functools.partial(validate_allof_anyof_oneof, sub_schemas=anyOf, context=context, method=any)
+
+
+def generate_oneof_validator(oneOf, context, **kwargs):
+    return functools.partial(validate_allof_anyof_oneof, sub_schemas=oneOf, context=context, method=exactly_one)
 
 
 def validate_object(obj, field_validators=None, non_field_validators=None,

flex/validation/schema.py

@@ -37,6 +37,7 @@
     generate_object_validator,
     generate_allof_validator,
     generate_anyof_validator,
+    generate_oneof_validator,
 )
 from flex.datastructures import (
     ValidationDict,
@@ -193,6 +194,7 @@ def generate_additional_properties_validator(additionalProperties, properties, *
     'items': generate_items_validator,
     'allOf': generate_allof_validator,
     'anyOf': generate_anyof_validator,
+    'oneOf': generate_oneof_validator,
 }
 
 

tests/validation/schema/test_oneof_validation.py

@@ -0,0 +1,56 @@
+
+import pytest
+
+from flex.exceptions import ValidationError
+from flex.constants import (
+    STRING,
+    INTEGER,
+)
+from flex.error_messages import MULTIPLE_OF_MESSAGES
+
+from tests.utils import (
+    generate_validator_from_schema,
+    assert_message_in_errors
+)
+
+
+def test_oneof_simple():
+    # example taken from http://spacetelescope.github.io/understanding-json-schema/reference/combining.html
+    schema = {
+        "oneOf": [
+            { "type": INTEGER, "multipleOf": 5 },
+            { "type": INTEGER, "multipleOf": 3 },
+        ]
+    }
+    validator = generate_validator_from_schema(schema)
+
+    validator(10)
+    validator(9)
+
+
+def test_one_of_complex_failure():
+    # example taken from http://spacetelescope.github.io/understanding-json-schema/reference/combining.html
+    schema = {
+        "oneOf": [
+            { "type": INTEGER, "multipleOf": 5 },
+            { "type": INTEGER, "multipleOf": 3 },
+        ]
+    }
+    validator = generate_validator_from_schema(schema)
+
+    with pytest.raises(ValidationError) as err:
+        validator(2)
+
+    assert_message_in_errors(
+        MULTIPLE_OF_MESSAGES['invalid'],
+        err.value.detail,
+    )
+
+    with pytest.raises(ValidationError) as err:
+        validator(15)
+
+    assert_message_in_errors(
+        MULTIPLE_OF_MESSAGES['invalid'],
+        err.value.detail,
+    )
+