GraphQL

Definition

• API query language that allows the client to request only the specific data fields it needs
• makes it possible to combine several different resources into a single request

• Related
  • HTTP Fundamentals
  • APIs, APIs - API Architectures

Example of GraphQL query

query {
  user(id: 1) {
    name
    email
    posts {
      title
    }
  }
}

• With a traditional REST API, this would have required at least two separate requests (e.g., to /users/1 and then to /users/1/posts). GraphQL solves this by getting all the required information in a single request.

Advantages

• Solves the disadvantages of REST API

Feature	Explanation
Solves Over-fetching	You don’t need to retrieve unnecessary data; you can specify exactly which fields you want.
Solves Under-fetching	You can request a combination of all the data you need from multiple resources in a single query.
Schema-centric	The API specification is consistently managed by the GraphQL schema, which serves as a single source of truth for clients and servers.
No Versioning Needed	Since clients can simply request different fields as the API evolves, there’s no need for versioned URLs like /v1 or /v2.

Disadvantages

• Complex Caching & Security: Implementing caching is more difficult than with standard REST APIs. Security logic, such as filtering which user can see which data field, can also become very complex.
  • You can’t just check the response/requests easily like on REST API (Chrome DevTool). You need to use the server itself
• High Learning Curve: There is a significant learning curve for both server and client-side developers when adopting GraphQL for the first time