Async GraphQL Helper Library
Project description
Cannula
GraphQL for people who like Python!
Why Cannula?
We wanted to make the world a better place, but we are programmers so we settled on making the web fun again. Too much attention has been given to Javascript client libraries. They all seem to compete on size and speed and features but most of them do not solve any of the actual problems you have. So while the todo application is quick and easy to follow the hard parts take a long time to complete.
Now a days if you want a fancy single page application you need to invest a good week or so planning out all the tools you will need to assemble your site. Every decision is full of sorrow and doubt as you google for the latest trends or how to setup unit tests. Or searching for a bootstrapped version of the library you like.
Using GraphQL you can simplify your web application stack and reduce dependencies to achieve the same customer experience without regret. By using just a few core libraries you can increase productivity and make your application easier to maintain.
Our Philosophy:
- Make your site easy to maintain.
- Document your code.
- Don't lock yourself into a framework.
- Be happy!
Installation
Requires Python 3.6 or greater! The only dependency is graphql-core-next.
pip3 install cannula
Quick Start
Here is a small hello world example:
import logging import typing import sys import cannula from cannula.middleware import DebugMiddleware SCHEMA = cannula.gql(""" type Message { text: String } type Query { hello(who: String): Message } """) logging.basicConfig(level=logging.DEBUG) api = cannula.API( __name__, schema=SCHEMA, middleware=[ DebugMiddleware() ] ) class Message(typing.NamedTuple): text: str # The query resolver takes a source and info objects # and any arguments defined by the schema. Here we # only accept a single argument `who`. @api.resolver('Query') async def hello(source, info, who): return Message(f"Hello, {who}!") # Pre-parse your query to speed up your requests. # Here is an example of how to pass arguments to your # query functions. SAMPLE_QUERY = cannula.gql(""" query HelloWorld ($who: String!) { hello(who: $who) { text } } """) who = 'world' if len(sys.argv) > 1: who = sys.argv[1] print(api.call_sync(SAMPLE_QUERY, variables={'who': who}))
Now you should see the results if you run the sample on the command line:
$ python3 examples/hello.py DEBUG:asyncio:Using selector: KqueueSelector DEBUG:cannula.schema:Adding default empty Mutation type DEBUG:cannula.middleware.debug:Resolving Query.hello expecting type Message DEBUG:cannula.middleware.debug:Field Query.hello resolved: Message(text='Hello, world!') in 0.000108 seconds DEBUG:cannula.middleware.debug:Resolving Message.text expecting type String DEBUG:cannula.middleware.debug:Field Message.text resolved: 'Hello, world!' in 0.000067 seconds ExecutionResult( data={'hello': {'text': 'Hello, world!'}}, errors=None ) $ python3 examples/hello.py Bob DEBUG:asyncio:Using selector: KqueueSelector DEBUG:cannula.schema:Adding default empty Mutation type DEBUG:cannula.middleware.debug:Resolving Query.hello expecting type Message DEBUG:cannula.middleware.debug:Field Query.hello resolved: Message(text='Hello, Bob!') in 0.000104 seconds DEBUG:cannula.middleware.debug:Resolving Message.text expecting type String DEBUG:cannula.middleware.debug:Field Message.text resolved: 'Hello, Bob!' in 0.000101 seconds ExecutionResult( data={'hello': {'text': 'Hello, Bob!'}}, errors=None )
But what about Django integration or flask?
# pip install channels, Django import cannula from channels.db import database_sync_to_async from django.contrib.auth.models import User schema = cannula.gql(""" type User { username: String # Only expose the fields you actually use first_name: String last_name: String made_up_field: String } extend type Query { getUserById(user_id: String): User } """) @api.query() async def getUserById(source, info, user_id): return await get_user(user_id) @database_sync_to_async def get_user(user_id): return User.objects.get(pk=user_id) @api.resolve('User') async def made_up_field(source, info): return f"{source.get_full_name()} is a lying lier there is no 'made_up_field'"
Since GraphQL is agnostic about where or how you store your data all you need to do is provide a function to resolve a query. The results you return just need to match the schema and you are done.
Django and sqlalchemy already provide tools to query the database. And they work quite well. Or you may choose to use an async database library to make concurrent requests work even better. Try them all and see what works best for your team and your use case.
Examples and Documentation
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