Custom Server example with Flask

Hey there! I ported the custom server example from django to flask.

It’s quite short and it would be nice to add it to the docs.

from ariadne import gql, ResolverMap, make_executable_schema
from ariadne.constants import PLAYGROUND_HTML
from graphql import format_error, graphql_sync
from flask import request, jsonify
from flask.views import MethodView

type_defs = gql("""
    type Query {
        hello: String!
    }
""")


query = ResolverMap("Query")


@query.field("hello")
def resolve_hello(_, info):
    request = info.context
    print(request.headers)
    user_agent = request.headers.get("User-Agent", "Guest")
    return "Hello, %s!" % user_agent


schema = make_executable_schema(type_defs, query)


class GraphQlView(MethodView):

    def get(self):
        return PLAYGROUND_HTML, 200

    def post(self):
        data = request.get_json()
        if data is None or not isinstance(data, dict):
            return 'Bad Request', 400

        variables = data.get('variables')
        if variables and not isinstance(variables, dict):
            return 'Bad Request', 400

        # Note: Passing the request to the context is option. In Flask, the current
        #   request is allways accessible as flask.request.
        result = graphql_sync(
            schema,
            data.get('query'),
            context_value=request,
            variable_values=variables,
            operation_name=data.get('operationName')
        )

        response = {"data": result.data}
        if result.errors:
            response["errors"] = [format_error(e) for e in result.errors]

        return jsonify(response)

[jrast]

I rewrote the example as a complete flask application, which is ready to run:

from ariadne import gql, ResolverMap, make_executable_schema
from ariadne.constants import PLAYGROUND_HTML
from graphql import format_error, graphql_sync
from flask import Flask, request, jsonify


type_defs = gql("""
    type Query {
        hello: String!
    }
""")


query = ResolverMap("Query")


@query.field("hello")
def resolve_hello(_, info):
    request = info.context
    user_agent = request.headers.get("User-Agent", "Guest")
    return "Hello, %s!" % user_agent


app = Flask(__name__)


@app.route('/graphql/', methods=['GET'])
def graphql_playgroud():
    """Serving the GraphQL Playground

    Note: This endpoint is not required if you do not want to provide the playground.
      But keep in mind that clients can still explore your API, for example by
      using the GraphQL desktop app.
    """
    return PLAYGROUND_HTML, 200


@app.route('/graphql/', methods=['POST'])
def graphql_server():
    """Serve GraphQL queries"""
    data = request.get_json()
    if data is None or not isinstance(data, dict):
        return 'Bad Request', 400

    variables = data.get('variables')
    if variables and not isinstance(variables, dict):
        return 'Bad Request', 400

    # Note: Passing the request to the context is option. In Flask, the current
    #   request is allways accessible as flask.request.
    result = graphql_sync(
        make_executable_schema(type_defs, query),
        data.get('query'),
        context_value=request,
        variable_values=variables,
        operation_name=data.get('operationName')
    )

    response = {"data": result.data}
    if result.errors:
        response["errors"] = [format_error(e) for e in result.errors]

    return jsonify(response)


if __name__ == '__main__':
    app.run(debug=True)

This structure is well known, even for Flask beginners. More expirienced users know how to adapt this to using Blueprints or a Method view.

[rafalp]

It’s been a while since I’ve did anything with flask, but wouldn’t something like this be possible and more idiomatic?

@app.route('/graphql/', methods=['GET'])
def graphql_playground():
    return PLAYGROUND_HTML, 200


@app.route('/graphql/', methods=['POST'])
def graphql_server():
    ...