graphene/UPGRADE-v2.0.md

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# v2.0 Upgrade Guide
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`ObjectType`, `Interface`, `InputObjectType`, `Scalar` and `Enum` implementations
have been quite simplified, without the need to define a explicit Metaclass for each subtype.
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It also improves the field resolvers, [simplifying the code](#simpler-resolvers) the
developer has to write to use them.
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**Deprecations:**
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* [`AbstractType`](#abstracttype-deprecated)
* [`resolve_only_args`](#resolve_only_args)
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* [`Mutation.Input`](#mutationinput)
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**Breaking changes:**
* [`Simpler Resolvers`](#simpler-resolvers)
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* [`Node Connections`](#node-connections)
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**New Features!**
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* [`InputObjectType`](#inputobjecttype)
* [`Meta as Class arguments`](#meta-ass-class-arguments) (_only available for Python 3_)
> The type metaclasses are now deleted as they are no longer necessary. If your code was depending
> on this strategy for creating custom attrs, see an [example on how to do it in 2.0](https://github.com/graphql-python/graphene/blob/v2.0.0/graphene/tests/issues/test_425.py).
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## Deprecations
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### AbstractType deprecated
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AbstractType is deprecated in graphene 2.0, you can now use normal inheritance instead.
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Before:
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```python
class CommonFields(AbstractType):
name = String()
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class Pet(CommonFields, Interface):
pass
```
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With 2.0:
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```python
class CommonFields(object):
name = String()
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class Pet(CommonFields, Interface):
pass
```
### resolve\_only\_args
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`resolve_only_args` is now deprecated as the resolver API has been simplified.
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Before:
```python
class User(ObjectType):
name = String()
@resolve_only_args
def resolve_name(self):
return self.name
```
With 2.0:
```python
class User(ObjectType):
name = String()
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def resolve_name(self, info):
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return self.name
```
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### Mutation.Input
`Mutation.Input` is now deprecated in favor of using `Mutation.Arguments` (`ClientIDMutation` still uses `Input`).
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Before:
```python
class User(Mutation):
class Input:
name = String()
```
With 2.0:
```python
class User(Mutation):
class Arguments:
name = String()
```
## Breaking Changes
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### Simpler resolvers
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All the resolvers in graphene have been simplified.
Prior to Graphene `2.0`, all resolvers required four arguments: `(root, args, context, info)`.
Now, resolver `args` are passed as keyword arguments to the function, and `context` argument dissapeared in favor of `info.context`.
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Before:
```python
my_field = graphene.String(my_arg=graphene.String())
def resolve_my_field(self, args, context, info):
my_arg = args.get('my_arg')
return ...
```
With 2.0:
```python
my_field = graphene.String(my_arg=graphene.String())
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def resolve_my_field(self, info, my_arg):
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return ...
```
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And, if you need the context in the resolver, you can use `info.context`:
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```python
my_field = graphene.String(my_arg=graphene.String())
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def resolve_my_field(self, info, my_arg):
context = info.context
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return ...
```
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### Node Connections
Node types no longer have a `Connection` by default.
In 2.0 and onwards `Connection`s should be defined explicitly.
Before:
```python
class User(ObjectType):
class Meta:
interfaces = [relay.Node]
name = String()
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class Query(ObjectType):
user_connection = relay.ConnectionField(User)
```
With 2.0:
```python
class User(ObjectType):
class Meta:
interfaces = [relay.Node]
name = String()
class UserConnection(relay.Connection):
class Meta:
node = User
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class Query(ObjectType):
user_connection = relay.ConnectionField(UserConnection)
```
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## Node.get_node
The method `get_node` in `ObjectTypes` that have `Node` as interface, changes its API.
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From `def get_node(cls, id, context, info)` to `def get_node(cls, info, id)`.
```python
class MyObject(ObjectType):
class Meta:
interfaces = (Node, )
@classmethod
def get_node(cls, id, context, info):
return ...
```
To:
```python
class MyObject(ObjectType):
class Meta:
interfaces = (Node, )
@classmethod
def get_node(cls, info, id):
return ...
```
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## Mutation.mutate
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Now only receives (`root`, `info`, `**args`)
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## ClientIDMutation.mutate_and_get_payload
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Now only receives (`root`, `info`, `**input`)
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## New Features
### InputObjectType
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If you are using `InputObjectType`, you now can access
its fields via `getattr` (`my_input.myattr`) when resolving, instead of
the classic way `my_input['myattr']`.
And also use custom defined properties on your input class.
Example. Before:
```python
class UserInput(InputObjectType):
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id = ID(required=True)
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def is_valid_input(input):
return input.get('id').startswith('userid_')
class Query(ObjectType):
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user = graphene.Field(User, input=UserInput())
@resolve_only_args
def resolve_user(self, input):
user_id = input.get('id')
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if is_valid_input(user_id):
return get_user(user_id)
```
With 2.0:
```python
class UserInput(InputObjectType):
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id = ID(required=True)
@property
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def is_valid(self):
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return self.id.startswith('userid_')
class Query(ObjectType):
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user = graphene.Field(User, input=UserInput())
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def resolve_user(self, info, input):
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if input.is_valid:
return get_user(input.id)
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```
### Meta as Class arguments
Now you can use the meta options as class arguments (**ONLY PYTHON 3**).
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Before:
```python
class Dog(ObjectType):
class Meta:
interfaces = [Pet]
name = String()
```
With 2.0:
```python
class Dog(ObjectType, interfaces=[Pet]):
name = String()
```
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### Abstract types
Now you can create abstact types super easily, without the need of subclassing the meta.
```python
class Base(ObjectType):
class Meta:
abstract = True
id = ID()
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def resolve_id(self, info):
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return "{type}_{id}".format(
type=self.__class__.__name__,
id=self.id
)
```
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### UUID Scalar
In Graphene 2.0 there is a new dedicated scalar for UUIDs, `UUID`.