Which is better to use: REST or GraphQL?

REST and GraphQL are different approaches to building APIs, each with its own advantages and disadvantages. The choice depends on the specifics of the project.

REST

• Advantages: Easy to understand and implement, widely used, well-suited for simple APIs with clearly defined resources, supports HTTP-level caching.
• Disadvantages: Can lead to "over-fetching" (retrieving excess data) or "under-fetching" (insufficient data), requires multiple requests to fetch related resources, complexity in API version management.

GraphQL

• Advantages: Allows clients to request only the necessary data, reduces the number of requests, flexible in fetching related data, strong data typing.
• Disadvantages: More complex to learn and implement on the backend, requires additional infrastructure (GraphQL server), may be less efficient for simple queries, caching is less straightforward compared to REST.

Comparison Table

Parameter	REST	GraphQL
Data Retrieval	Fixed endpoints	Client requests specific fields
Redundancy	Possible "over-fetching"	Minimizes redundant data
Requests	Multiple requests for related data	Single request for related data
Versions	Complex version management	Easier to add/remove fields
Caching	Built-in at HTTP level	Requires additional logic
Complexity	Easier to learn and implement	Backend complexity

Code Examples

• REST - Get user and their posts:

  // Get user
  fetch('/users/1')
    .then(response => response.json())
    .then(user => {
      console.log(user);
  
      // Get user's posts
      fetch(`/users/${user.id}/posts`)
        .then(response => response.json())
        .then(posts => {
          console.log(posts);
        });
    });
  

• GraphQL - Get user and their posts in one request:

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

Conclusions:

• For simple APIs, static data, or when simplicity and speed of development are important, REST may be the best choice.
• For complex applications, mobile clients, microservice architecture, or when high flexibility in data retrieval and minimizing network traffic are required, GraphQL is more preferable.

Often, in real projects, a combination of both approaches is used, where REST is used for some tasks, and GraphQL for others.