Merge pull request #81 from fuhrysteve/implement-field-subclass-check

[build] Implement field subclass check

.travis.yml

@@ -33,6 +33,6 @@ before_install:
 
 install:
   - pip install -r requirements-tox.txt
-  - pip install tox-travis coveralls
+  - pip install -U tox-travis coveralls
 script: make tox
 after_success: coveralls

marshmallow_jsonschema/base.py

@@ -148,22 +148,26 @@ def _from_python_type(self, obj, field, pytype):
             json_schema["items"] = self._get_schema_for_field(obj, list_inner(field))
         return json_schema
 
+    def _get_pytype(self, field, mapping):
+        """Get pytype based on field subclass"""
+        for map_class, pytype in mapping.items():
+            if issubclass(field.__class__, map_class):
+                return pytype
+        raise UnsupportedValueError("unsupported field type %s" % field)
+
     def _get_schema_for_field(self, obj, field):
         """Get schema and validators for field."""
         mapping = self._get_default_mapping(obj)
         if hasattr(field, "_jsonschema_type_mapping"):
             schema = field._jsonschema_type_mapping()
         elif "_jsonschema_type_mapping" in field.metadata:
             schema = field.metadata["_jsonschema_type_mapping"]
-        elif field.__class__ in mapping:
-            pytype = mapping[field.__class__]
+        else:
+            pytype = self._get_pytype(field, mapping)
             if isinstance(pytype, basestring):
                 schema = getattr(self, pytype)(obj, field)
             else:
                 schema = self._from_python_type(obj, field, pytype)
-        else:
-            raise UnsupportedValueError("unsupported field type %s" % field)
-
         # Apply any and all validators that field may have
         for validator in field.validators:
             if validator.__class__ in FIELD_VALIDATORS:

tests/test_dump.py

@@ -351,6 +351,20 @@ class UserSchema(Schema):
     }
 
 
+def test_field_subclass():
+    """JSON schema generation should not fail on sublcass marshmallow field."""
+
+    class CustomField(fields.Field):
+        pass
+
+    class TestSchema(Schema):
+        myfield = CustomField()
+
+    schema = TestSchema()
+    with pytest.raises(UnsupportedValueError):
+        _ = validate_and_dump(schema)
+
+
 def test_readonly():
     class TestSchema(Schema):
         id = fields.Integer(required=True)