GraphQL vs REST in Python Backend Applications

Introduction

When building a backend application, one of a project's most critical decisions is choosing the right API architecture. For many years, REST has been the de-facto standard for building APIs. However, in recent years, GraphQL has emerged as a powerful alternative. In this article, we'll compare GraphQL and REST in the context of Python backend applications.

What is REST?

REST (Representational State Transfer) is an architectural style that uses a stateless, client-server communication protocol. In a RESTful API, resources are identified by URLs, and you use HTTP methods (GET, POST, PUT, DELETE) to interact with them.

Example: A Simple REST API with FastAPI

Here's an example of a simple REST API with FastAPI:

from fastapi import FastAPI

app = FastAPI()

@app.get("/users/{user_id}")
async def read_user(user_id: int):
    return {"user_id": user_id}

In this example, the /users/{user_id} endpoint returns the user with the specified ID.

What is GraphQL?

GraphQL is a query language for APIs and a runtime for fulfilling those queries with your existing data. Unlike REST, which exposes a fixed set of endpoints for each resource, GraphQL exposes a single endpoint that allows clients to request exactly the data they need.

Example: A Simple GraphQL API with Strawberry

Strawberry is a popular GraphQL library for Python that integrates well with FastAPI. Here's an example of a simple GraphQL API with Strawberry:

import strawberry
from fastapi import FastAPI
from strawberry.fastapi import GraphQLRouter

@strawberry.type
class Query:
    @strawberry.field
    def hello(self) -> str:
        return "Hello, world!"

schema = strawberry.Schema(query=Query)
graphql_app = GraphQLRouter(schema)

app = FastAPI()
app.include_router(graphql_app, prefix="/graphql")

In this example, the /graphql endpoint exposes a GraphQL schema with a single hello field.

Comparison

| Feature | REST | GraphQL | | --- | --- | --- | | Data Fetching | Multiple endpoints, over-fetching or under-fetching | Single endpoint, clients request exactly what they need | | Schema | No built-in schema, relies on documentation | Strongly typed schema | | Versioning | Typically done with URL versioning (e.g., /v1/users) | No versioning needed, new fields can be added without breaking existing clients |

Conclusion

Both REST and GraphQL have their strengths and weaknesses. REST is a great choice for simple APIs with well-defined resources, while GraphQL is a better choice for complex APIs with a wide variety of data requirements. Ultimately, the best choice for your application will depend on your specific needs and use case.