Difference between GraphQL and REST

Difference between GraphQL and REST (Representational State Transfer)

1. Data Fetching

• REST: Uses multiple endpoints for different resources. Each resource (e.g., /users, /posts) has its own endpoint, and to get data from multiple resources, you may need to make multiple requests.
• GraphQL: Uses a single endpoint for all requests. You can fetch exactly what you need in a single query, even if the data comes from multiple resources.

Example:

• REST: You may need to call /users and /posts separately to get data about users and their posts.
• GraphQL: A single query can fetch both users and their posts simultaneously.

2. Over-fetching and Under-fetching

• REST: Often leads to over-fetching or under-fetching. Over-fetching occurs when more data than necessary is retrieved, while under-fetching happens when you don't get enough data in one request, requiring additional requests.
• GraphQL: Minimizes over-fetching and under-fetching because you specify exactly the data fields you need in your query.

Example:

• REST: If you need only a user’s name but the /users endpoint returns name, email, and age, you get unwanted data.
• GraphQL: You can request only the name field.

3. Flexibility and Versioning

• REST: Typically requires versioning (/v1/users, /v2/users) as APIs evolve, which can lead to multiple endpoints for different versions.
• GraphQL: Doesn’t require versioning because the schema can evolve. New fields can be added without affecting existing queries.

4. Performance

• REST: Multiple round trips to the server may be needed to gather all necessary data, which can lead to slower performance.
• GraphQL: Typically faster for complex data fetching, as it reduces the number of requests by aggregating all needed data in one request.

Note: However, GraphQL can be less performant for simple, one-resource fetches because the server needs to parse and resolve a more complex query structure.

5. Error Handling

• REST: Uses HTTP status codes (e.g., 404, 500) to handle errors.
• GraphQL: Always returns a 200 OK status for queries but includes error details in the response’s error object, making it more uniform but less integrated with HTTP status codes.

6. Caching

• REST: Has better caching at the HTTP level because each endpoint corresponds to a specific resource that can be cached using standard techniques.
• GraphQL: More challenging to cache, as all requests go through a single endpoint, making it harder to leverage traditional HTTP caching mechanisms.

7. Tooling and Ecosystem

• REST: Is widely adopted with many mature libraries, frameworks, and built-in browser tools.
• GraphQL: Has a growing ecosystem with modern tools (e.g., Apollo Client), but requires more setup and learning, especially for caching and error handling.

8. Real-Time Data

• REST: Not natively designed for real-time data. Requires polling or additional tools (e.g., WebSockets) for real-time capabilities.
• GraphQL: Offers built-in support for real-time data through subscriptions.

Concise Summary:

Test Questions

• How does GraphQL handle over-fetching and under-fetching differently from REST?
• Why might GraphQL be less suitable for simple data-fetching tasks compared to REST?
• How does error handling differ between REST and GraphQL?
• In what scenarios would REST’s versioning be a disadvantage compared to GraphQL?
• By understanding these points, you can decide which approach—GraphQL or REST—best suits different requirements in API design and data fetching scenarios.