GQL

This is a GraphQL client for Python. Plays nicely with graphene, graphql-core, graphql-js and any other GraphQL implementation compatible with the spec.

GQL architecture is inspired by React-Relay and Apollo-Client.

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Installation

$ pip install gql

Please note that the following documentation describes the current version which is currently only available as a pre-relase and needs to be installed with

$ pip install --pre gql

Usage

The example below shows how you can execute queries against a local schema.

from gql import gql, Client

from .someSchema import SampleSchema

client = Client(schema=SampleSchema)
query = gql('''
    {
      hello
    }
''')

client.execute(query)

If you want to add additional headers when executing the query, you can specify these in a transport object:

from gql import Client
from gql.transport.requests import RequestsHTTPTransport

from .someSchema import SampleSchema

client = Client(transport=RequestsHTTPTransport(
     url='/graphql', headers={'Authorization': 'token'}), schema=SampleSchema)

To execute against a graphQL API. (We get the schema by using introspection).

from gql import gql, Client
from gql.transport.requests import RequestsHTTPTransport

sample_transport=RequestsHTTPTransport(
    url='https://countries.trevorblades.com/',
    verify=False,
    retries=3,
)

client = Client(
    transport=sample_transport,
    fetch_schema_from_transport=True,
)

query = gql('''
    query getContinents {
      continents {
        code
        name
      }
    }
''')

client.execute(query)

If you have a local schema stored as a schema.graphql file, you can do:

from graphql import build_ast_schema, parse
from gql import gql, Client

with open('path/to/schema.graphql') as source:
    document = parse(source.read())

schema = build_ast_schema(document)

client = Client(schema=schema)
query = gql('''
    {
      hello
    }
''')

client.execute(query)

With a python version > 3.6, it is possible to execute GraphQL subscriptions using the websockets transport:

from gql import gql, Client
from gql.transport.websockets import WebsocketsTransport

sample_transport = WebsocketsTransport(url='wss://your_server/graphql')

client = Client(
    transport=sample_transport,
    fetch_schema_from_transport=True,
)

query = gql('''
    subscription yourSubscription {
        ...
    }
''')

for result in client.subscribe(query):
    print (f"result = {result!s}")

Note: the websockets transport can also execute queries or mutations

Async usage with asyncio

When using the execute or subscribe function directly on the client, the execution is synchronous. It means that we are blocked until we receive an answer from the server and we cannot do anything else while waiting for this answer.

It is also possible to use this library asynchronously using asyncio.

Async Features:

To use the async features, you need to use an async transport:

HTTP async transport

This transport uses the aiohttp library

GraphQL subscriptions are not supported on the HTTP transport. For subscriptions you should use the websockets transport.

from gql import gql, Client
from gql.transport.aiohttp import AIOHTTPTransport
import asyncio

async def main():

    sample_transport = AIOHTTPTransport(
        url='https://countries.trevorblades.com/graphql',
        headers={'Authorization': 'token'}
    )

    async with Client(
        transport=sample_transport,
        fetch_schema_from_transport=True,
        ) as session:

        # Execute single query
        query = gql('''
            query getContinents {
              continents {
                code
                name
              }
            }
        ''')

        result = await session.execute(query)

        print(result)

asyncio.run(main())

Websockets async transport

The websockets transport uses the apollo protocol described here:

Apollo websockets transport protocol

This transport allows to do multiple queries, mutations and subscriptions on the same websocket connection

import logging
logging.basicConfig(level=logging.INFO)

from gql import gql, Client
from gql.transport.websockets import WebsocketsTransport
import asyncio

async def main():

    sample_transport = WebsocketsTransport(
        url='wss://countries.trevorblades.com/graphql',
        headers={'Authorization': 'token'}
    )

    async with Client(
        transport=sample_transport,
        fetch_schema_from_transport=True,
        ) as session:

        # Execute single query
        query = gql('''
            query getContinents {
              continents {
                code
                name
              }
            }
        ''')
        result = await session.execute(query)
        print(result)

        # Request subscription
        subscription = gql('''
            subscription {
                somethingChanged {
                    id
                }
            }
        ''')
        async for result in session.subscribe(subscription):
            print(result)

asyncio.run(main())

Websockets SSL

If you need to connect to an ssl encrypted endpoint:

import ssl

sample_transport = WebsocketsTransport(
    url='wss://SERVER_URL:SERVER_PORT/graphql',
    headers={'Authorization': 'token'}
)

If you have a self-signed ssl certificate, you need to provide an ssl_context with the server public certificate:

import pathlib
import ssl

ssl_context = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
localhost_pem = pathlib.Path(__file__).with_name("YOUR_SERVER_PUBLIC_CERTIFICATE.pem")
ssl_context.load_verify_locations(localhost_pem)

sample_transport = WebsocketsTransport(
    url='wss://SERVER_URL:SERVER_PORT/graphql',
    ssl=ssl_context
)

If you have also need to have a client ssl certificate, add:

ssl_context.load_cert_chain(certfile='YOUR_CLIENT_CERTIFICATE.pem', keyfile='YOUR_CLIENT_CERTIFICATE_KEY.key')

Websockets authentication

There are two ways to send authentication tokens with websockets depending on the server configuration.

  1. Using HTTP Headers
sample_transport = WebsocketsTransport(
    url='wss://SERVER_URL:SERVER_PORT/graphql',
    headers={'Authorization': 'token'}
)
  1. With a payload in the connection_init websocket message
sample_transport = WebsocketsTransport(
    url='wss://SERVER_URL:SERVER_PORT/graphql',
    init_payload={'Authorization': 'token'}
)

Async advanced usage

It is possible to send multiple GraphQL queries (query, mutation or subscription) in parallel, on the same websocket connection, using asyncio tasks


async def execute_query1():
    result = await session.execute(query1)
    print(result)

async def execute_query2():
    result = await session.execute(query2)
    print(result)

async def execute_subscription1():
    async for result in session.subscribe(subscription1):
        print(result)

async def execute_subscription2():
    async for result in session.subscribe(subscription2):
        print(result)

task1 = asyncio.create_task(execute_query1())
task2 = asyncio.create_task(execute_query2())
task3 = asyncio.create_task(execute_subscription1())
task4 = asyncio.create_task(execute_subscription2())

await task1
await task2
await task3
await task4

Subscriptions tasks can be stopped at any time by running

task.cancel()

Contributing

See CONTRIBUTING.md

License

MIT License