Custom server example
=====================

In addition to simple a GraphQL server implementation in the form of ``GraphQLMiddleware``, Ariadne provides building blocks for assembling custom GraphQL servers.


Creating executable schema
--------------------------

The key piece of the GraphQL server is an *executable schema* - a schema with resolver functions attached to fields.

Ariadne provides a ``make_executable_schema`` utility function that takes type definitions as a first argument and bindables as the second, and returns an executable instance of ``GraphQLSchema``::

    from ariadne import QueryType, make_executable_schema

    type_defs = """
        type Query {
            hello: String!
        }
    """

    query = QueryType()

    @query.field("hello")
    def resolve_hello(*_):
        return "Hello world!"

    schema = make_executable_schema(type_defs, query)
    
This schema can then be passed to the ``graphql`` query executor together with the query and variables::

    from graphql import graphql

    result = graphql(schema, query, variable_values={})


Basic GraphQL server with Django
--------------------------------

The following example presents a basic GraphQL server using a Django framework::

    import json

    from ariadne import QueryType, graphql_sync, make_executable_schema
    from ariadne.constants import PLAYGROUND_HTML
    from django.conf import settings
    from django.http import (
        HttpResponseBadRequest, JsonResponse
    )
    from django.views.decorators.csrf import csrf_exempt
    from graphql import graphql_sync

    type_defs = """
        type Query {
            hello: String!
        }
    """

    query = QueryType()


    @query.field("hello")
    def resolve_hello(*_):
        return "Hello world!"


    # Create executable schema instance
    schema = make_executable_schema(type_defs, query)


    # Create the view
    @csrf_exempt
    def graphql_view(request):
        # On GET request serve GraphQL Playground
        # You don't need to provide Playground if you don't want to
        # but keep on mind this will not prohibit clients from
        # exploring your API using desktop GraphQL Playground app.
        if request.method == "GET":
            return HttpResponse(PLAYGROUND_HTML)

        # GraphQL queries are always sent as POST
        if request.method != "POST":
            return HttpResponseBadRequest()

        if request.content_type != "application/json":
            return HttpResponseBadRequest()

        # Naively read data from JSON request
        try:
            data = json.loads(request.body)
        except ValueError:
            return HttpResponseBadRequest()

        # Execute the query
        success, result = graphql_sync(
            schema,
            data,
            context_value=request,  # expose request as info.context
            debug=settings.DEBUG,
        )

        status_code = 200 if success else 400
        # Send response to client
        return JsonResponse(result, status=status_code)