Merge pull request #376 from ThiefMaster/customizable-schema

Make schema class configurable

CHANGELOG.rst

@@ -1,6 +1,14 @@
 Changelog
 ---------
 
+5.2.0 (unreleased)
+******************
+
+Features:
+
+* Make the schema class used when generating a schema from a
+  dict overridable (:issue:`375`)
+
 5.1.3 (2019-03-11)
 ******************
 

src/webargs/asyncparser.py

@@ -126,7 +126,7 @@ def use_args(
         # Optimization: If argmap is passed as a dictionary, we only need
         # to generate a Schema once
         if isinstance(argmap, Mapping):
-            argmap = core.dict2schema(argmap)()
+            argmap = core.dict2schema(argmap, self.schema_class)()
 
         def decorator(func: typing.Callable) -> typing.Callable:
             req_ = request_obj

src/webargs/core.py

@@ -51,7 +51,7 @@ def _callable_or_raise(obj):
         return obj
 
 
-def dict2schema(dct):
+def dict2schema(dct, schema_class=ma.Schema):
     """Generate a `marshmallow.Schema` class given a dictionary of
     `Fields <marshmallow.fields.Field>`.
     """
@@ -64,7 +64,7 @@ class Meta(object):
             register = False
 
     attrs["Meta"] = Meta
-    return type(str(""), (ma.Schema,), attrs)
+    return type(str(""), (schema_class,), attrs)
 
 
 def is_multiple(field):
@@ -162,7 +162,10 @@ class Parser(object):
     :param callable error_handler: Custom error handler function.
     """
 
+    #: Default locations to check for data
     DEFAULT_LOCATIONS = ("querystring", "form", "json")
+    #: The marshmallow Schema class to use when creating new schemas
+    DEFAULT_SCHEMA_CLASS = ma.Schema
     #: Default status code to return for validation errors
     DEFAULT_VALIDATION_STATUS = DEFAULT_VALIDATION_STATUS
     #: Default error message for validation errors
@@ -179,9 +182,10 @@ class Parser(object):
         "files": "parse_files",
     }
 
-    def __init__(self, locations=None, error_handler=None):
+    def __init__(self, locations=None, error_handler=None, schema_class=None):
         self.locations = locations or self.DEFAULT_LOCATIONS
         self.error_callback = _callable_or_raise(error_handler)
+        self.schema_class = schema_class or self.DEFAULT_SCHEMA_CLASS
         #: A short-lived cache to store results from processing request bodies.
         self._cache = {}
 
@@ -309,7 +313,7 @@ def _get_schema(self, argmap, req):
         elif callable(argmap):
             schema = argmap(req)
         else:
-            schema = dict2schema(argmap)()
+            schema = dict2schema(argmap, self.schema_class)()
         if MARSHMALLOW_VERSION_INFO[0] < 3 and not schema.strict:
             warnings.warn(
                 "It is highly recommended that you set strict=True on your schema "
@@ -439,7 +443,7 @@ def greet(args):
         # Optimization: If argmap is passed as a dictionary, we only need
         # to generate a Schema once
         if isinstance(argmap, Mapping):
-            argmap = dict2schema(argmap)()
+            argmap = dict2schema(argmap, self.schema_class)()
 
         def decorator(func):
             req_ = request_obj

src/webargs/fields.py

@@ -32,6 +32,10 @@
 class Nested(ma.fields.Nested):
     """Same as `marshmallow.fields.Nested`, except can be passed a dictionary as
     the first argument, which will be converted to a `marshmallow.Schema`.
+
+    Note: The schema class here will always be `marshmallow.Schema`, regardless
+    of whether a custom schema class is set on the parser. Pass an explicit schema
+    class if necessary.
     """
 
     def __init__(self, nested, *args, **kwargs):

src/webargs/pyramidparser.py

@@ -137,7 +137,7 @@ def use_args(
         # Optimization: If argmap is passed as a dictionary, we only need
         # to generate a Schema once
         if isinstance(argmap, collections.Mapping):
-            argmap = core.dict2schema(argmap)()
+            argmap = core.dict2schema(argmap, self.schema_class)()
 
         def decorator(func):
             @functools.wraps(func)

tests/test_core.py

@@ -5,7 +5,7 @@
 import datetime
 
 import pytest
-from marshmallow import Schema, post_load, class_registry, validates_schema
+from marshmallow import Schema, post_load, pre_load, class_registry, validates_schema
 from werkzeug.datastructures import MultiDict as WerkMultiDict
 from django.utils.datastructures import MultiValueDict as DjMultiDict
 from bottle import MultiDict as BotMultiDict
@@ -1052,3 +1052,36 @@ def test_parse_with_error_status_code_and_headers(web_request):
     error = excinfo.value
     assert error.status_code == 418
     assert error.headers == {"X-Foo": "bar"}
+
+
+@mock.patch("webargs.core.Parser.parse_json")
+def test_custom_schema_class(parse_json, web_request):
+    class CustomSchema(Schema):
+        @pre_load
+        def pre_load(self, data):
+            data["value"] += " world"
+            return data
+
+    parse_json.return_value = "hello"
+    argmap = {"value": fields.Str()}
+    p = Parser(schema_class=CustomSchema)
+    ret = p.parse(argmap, web_request)
+    assert ret == {"value": "hello world"}
+
+
+@mock.patch("webargs.core.Parser.parse_json")
+def test_custom_default_schema_class(parse_json, web_request):
+    class CustomSchema(Schema):
+        @pre_load
+        def pre_load(self, data):
+            data["value"] += " world"
+            return data
+
+    class CustomParser(Parser):
+        DEFAULT_SCHEMA_CLASS = CustomSchema
+
+    parse_json.return_value = "hello"
+    argmap = {"value": fields.Str()}
+    p = CustomParser()
+    ret = p.parse(argmap, web_request)
+    assert ret == {"value": "hello world"}