Integration of FastAPI with GraphQL

In this tutorial, we will explore how to integrate GraphQL with FastAPI, a modern web framework for building APIs with Python. GraphQL is a query language for APIs that allows clients to request only the data they need. FastAPI is a high-performance web framework for building APIs quickly and efficiently.

To get started, make sure you have Python installed on your machine. You can install FastAPI and GraphQL by running the following commands in your terminal:

pip install fastapi
pip install graphene
pip install uvicorn

Once you have all the necessary packages installed, let’s create a new project directory and navigate into it:

mkdir fastapi-graphql
cd fastapi-graphql

Create a new Python file called main.py and open it in your favorite text editor. We will start by importing the necessary modules and creating a FastAPI app:

from fastapi import FastAPI
from graphene import ObjectType, String, Schema
from starlette.graphql import GraphQLApp

app = FastAPI()

Next, we will define a simple GraphQL schema using the graphene library. In this example, we will create a Query object with a single field called hello that returns a greeting message:

class Query(ObjectType):
    hello = String(name=String(default_value="stranger"))

    def resolve_hello(self, info, name):
        return f"Hello, {name}!"

Now, we will create a GraphQL schema using the Schema class, passing in our Query object:

schema = Schema(query=Query)

To serve our GraphQL API, we will create a new route in our FastAPI app that uses the GraphQLApp class to expose our GraphQL schema:

@app.get("/graphql")
async def graphql():
    return GraphQLApp(schema=schema)

Finally, we will run our FastAPI server using the uvicorn package:

uvicorn main:app --reload

Navigate to http://localhost:8000/graphql in your web browser to access the GraphiQL web interface for testing queries. You can execute the following query to test our hello field:

query {
  hello(name: "Alice")
}

You should see the following response:

{
  "data": {
    "hello": "Hello, Alice!"
  }
}

Congratulations! You have successfully integrated GraphQL with FastAPI. You can now expand your schema with additional types and queries to build more complex APIs. Happy coding!