Merge pull request #883 from graphql-python/update-object-type-docs

Update documentation on ObjectTypes

docs/types/objecttypes.rst

@@ -25,8 +25,8 @@ This example model defines a Person, with a first and a last name:
         last_name = graphene.String()
         full_name = graphene.String()
 
-        def resolve_full_name(self, info):
+        def resolve_full_name(root, info):
-            return '{} {}'.format(self.first_name, self.last_name)
+            return '{} {}'.format(root.first_name, root.last_name)
 
 **first\_name** and **last\_name** are fields of the ObjectType. Each
 field is specified as a class attribute, and each attribute maps to a
@@ -56,23 +56,148 @@ NOTE: The resolvers on an ``ObjectType`` are always treated as ``staticmethod``\
 so the first argument to the resolver method ``self`` (or ``root``) need
 not be an actual instance of the ``ObjectType``.
 
+If an explicit resolver is not defined on the ``ObjectType`` then Graphene will
+attempt to use a property with the same name on the object that is passed to the
+``ObjectType``.
 
-Quick example
+.. code:: python
-~~~~~~~~~~~~~
 
-This example model defines a ``Query`` type, which has a reverse field
+    import graphene
-that reverses the given ``word`` argument using the ``resolve_reverse``
+
-method in the class.
+    class Person(graphene.ObjectType):
+        first_name = graphene.String()
+        last_name = graphene.String()
+
+    class Query(graphene.ObjectType):
+        me = graphene.Field(Person)
+
+        def resolve_me(_, info):
+            # returns an object that represents a Person
+            return get_human(name='Luke Skywalker')
+
+If you are passing a dict instead of an object to your ``ObjectType`` you can
+change the default resolver in the ``Meta`` class like this:
+
+.. code:: python
+
+    import graphene
+    from graphene.types.resolver import dict_resolver
+
+    class Person(graphene.ObjectType):
+        class Meta:
+            default_resolver = dict_resolver
+
+        first_name = graphene.String()
+        last_name = graphene.String()
+
+    class Query(graphene.ObjectType):
+        me = graphene.Field(Person)
+
+        def resolve_me(_, info):
+            return {
+                "first_name": "Luke",
+                "last_name": "Skywalker",
+            }
+
+Or you can change the default resolver globally by calling ``set_default_resolver``
+before executing a query.
+
+.. code:: python
+
+    import graphene
+    from graphene.types.resolver import dict_resolver, set_default_resolver
+
+    set_default_resolver(dict_resolver)
+
+    schema = graphene.Schema(query=Query)
+    result = schema.execute('''
+        query {
+            me {
+                firstName
+            }
+        }
+     ''')
+
+
+Resolvers with arguments
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+Any arguments that a field defines gets passed to the resolver function as
+kwargs. For example:
 
 .. code:: python
 
     import graphene
 
     class Query(graphene.ObjectType):
-        reverse = graphene.String(word=graphene.String())
+        human_by_name = graphene.Field(Human, name=graphene.String(required=True))
+
+        def resolve_human_by_name(_, info, name):
+            return get_human(name=name)
+
+You can then execute the following query:
+
+.. code::
+
+    query {
+        humanByName(name: "Luke Skywalker") {
+            firstName
+            lastName
+        }
+    }
+
+NOTE: if you define an argument for a field that is not required (and in a query
+execution it is not provided as an argument) it will not be passed to the
+resolver function at all. This is so that the developer can differenciate
+between a ``undefined`` value for an argument and an explicit ``null`` value.
+
+For example, given this schema:
+
+.. code:: python
+
+    import graphene
+
+    class Query(graphene.ObjectType):
+        hello = graphene.String(required=True, name=graphene.String())
+
+        def resolve_hello(_, info, name):
+            return name if name else 'World'
+
+And this query:
+
+.. code::
+
+    query {
+        hello
+    }
+
+An error will be thrown:
+
+.. code::
+
+    TypeError: resolve_hello() missing 1 required positional argument: 'name'
+
+You can fix this error in 2 ways. Either by combining all keyword arguments
+into a dict:
+
+.. code:: python
+
+    class Query(graphene.ObjectType):
+        hello = graphene.String(required=True, name=graphene.String())
+
+        def resolve_hello(_, info, **args):
+            return args.get('name', 'World')
+
+Or by setting a default value for the keyword argument:
+
+.. code:: python
+
+    class Query(graphene.ObjectType):
+        hello = graphene.String(required=True, name=graphene.String())
+
+        def resolve_hello(_, info, name='World'):
+            return name
 
-        def resolve_reverse(self, info, word):
-            return word[::-1]
 
 Resolvers outside the class
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -83,11 +208,13 @@ A field can use a custom resolver from outside the class:
 
     import graphene
 
-    def reverse(root, info, word):
+    def resolve_full_name(person, info):
-        return word[::-1]
+        return '{} {}'.format(person.first_name, person.last_name)
 
-    class Query(graphene.ObjectType):
+    class Person(graphene.ObjectType):
-        reverse = graphene.String(word=graphene.String(), resolver=reverse)
+        first_name = graphene.String()
+        last_name = graphene.String()
+        full_name = graphene.String(resolver=resolve_full_name)
 
 
 Instances as data containers

graphene/utils/str_converters.py

@@ -18,4 +18,4 @@ def to_snake_case(name):
 
 
 def to_const(string):
-    return re.sub("[\W|^]+", "_", string).upper()
+    return re.sub("[\W|^]+", "_", string).upper()  # noqa