graphene-pydantic 0.0.4

Graphene Pydantic integration

graphene-pydantic

A Pydantic integration for Graphene.

Installation

pip install "graphene-pydantic"

Examples

Here is a simple Pydantic model:

import pydantic

class PersonModel(pydantic.BaseModel):
    id: uuid.UUID
    first_name: str
    last_name: str

To create a GraphQL schema for it you simply have to write the following:

import graphene
from graphene_pydantic import PydanticObjectType

class Person(PydanticObjectType):
    class Meta:
        model = PersonModel
        # only return specified fields
        only_fields = ("name",)
        # exclude specified fields
        exclude_fields = ("id",)

class Query(graphene.ObjectType):
    people = graphene.List(Person)

    def resolve_people(self, info):
        return get_people()  # function returning `PersonModel`s

schema = graphene.Schema(query=Query)

Then you can simply query the schema:

query = '''
    query {
      people {
        firstName,
        lastName
      }
    }
'''
result = schema.execute(query)

Forward declarations and circular references

graphene_pydantic supports forward declarations and circular references, but you will need to call the resolve_placeholders() method to ensure the types are fully updated before you execute a GraphQL query. For instance:

class NodeModel(BaseModel):
    id: int
    name: str
    labels: 'LabelsModel'
    
class LabelsModel(BaseModel):
    node: NodeModel
    labels: typing.List[str]
    
class Node(PydanticObjectType):
    class Meta:
        model = NodeModel
        
class Labels(PydanticObjectType):
    class Meta:
        model = LabelsModel
        

Node.resolve_placeholders()  # make the `labels` field work
Labels.resolve_placeholders()  # make the `node` field work

Full Examples

Please see the examples directory for more.

License

This project is under the Apache License.

Third Party Code

This project depends on third-party code which is subject to the licenses set forth in Third Party Licenses.

Contributing

Please see the Contributing Guide. Note that you must sign the CLA.

Caveats

Note that even though Pydantic is perfectly happy with fields that hold mappings (e.g. dictionaries), because GraphQL's type system doesn't have them those fields can't be exported to Graphene types. For instance, this will fail with an error Don't know how to handle mappings in Graphene:

import typing
from graphene_pydantic import PydanticObjectType

class Pet:
  pass

class Person:
  name: str
  pets_by_name: typing.Dict[str, Pet]
  
class GraphQLPerson(PydanticObjectType):  
  class Meta:
    model = Person

However, note that if you use exclude_fields or only_fields to exclude those values, there won't be a problem:

class GraphQLPerson(PydanticObjectType):
  class Meta:
    model = Person
    exclude_fields = ("pets_by_name",)