GraphQL vs REST
Tags: graphql, api, programming, tutorial
Published: 2023-01-30 08:54:12

GraphQL and REST are two popular API architectures for building web applications. Both have been widely used for building modern applications and have their own advantages and disadvantages. In this article, we will compare and contrast GraphQL and REST, explore the benefits of each, and provide code examples to illustrate the differences.

**What is GraphQL?** GraphQL is a query language for APIs that was developed by Facebook in 2012. It provides a more efficient and flexible alternative to traditional REST APIs by allowing clients to request exactly the data they need, reducing the risk of over-fetching or under-fetching data. GraphQL also includes a type system that defines the data that can be fetched and the operations that can be performed, making it easier for clients and servers to understand the API.

**What is REST?** REST, or Representational State Transfer, is an architectural style for building web services that was first described by Roy Fielding in 2000. REST APIs use HTTP methods (such as GET, POST, PUT, and DELETE) to perform operations on resources. REST APIs typically return all the data associated with a resource, which can result in over-fetching data.

### Code Examples ###

Let’s look at a simple code example to see the difference between a GraphQL API and a REST API.

Here is an example of a simple GraphQL query to retrieve information about a user:

```
query {
  user(id: 1) {
    name
    email
  }
}
```

And here is an equivalent REST API call to retrieve the same information:

```
GET /users/1
```

As you can see, the GraphQL query allows you to specify exactly what data you want to retrieve, while the REST API call returns all the data associated with the user resource.


### Benefits of GraphQL ###

- Flexibility: GraphQL allows clients to request exactly the data they need, reducing the risk of over-fetching or under-fetching data. This makes it easier to optimize performance and reduce network overhead.
- Efficient: GraphQL allows clients to fetch multiple resources in a single request, reducing the number of round trips to the server. This can greatly improve performance, especially for mobile devices with slow or unreliable network connections.
- Type System: GraphQL includes a type system that defines the data that can be fetched and the operations that can be performed, making it easier for clients and servers to understand the API.
- Versioning: GraphQL has a built-in versioning system through its schema, which allows for new fields and types to be added without breaking existing clients.

### Benefits of REST ###

- Simple: REST is a simple and well-established architecture that provides a straightforward way to build APIs.
- Backwards Compatible: REST APIs are typically designed to be backwards compatible, which means that new versions of the API can be introduced without breaking existing clients.
- Widely Adopted: REST is a widely adopted architecture and has a large community of developers and tools that support it.
- Caching: REST APIs can be cached, reducing network overhead and improving performance.


### N+1 Problem ###

The n+1 problem is a common issue in REST API design, where multiple API calls are required to retrieve related data. For example, to retrieve information about a user and their posts, you might need to make two separate API calls: one to retrieve the user information and another to retrieve the list of posts.

In GraphQL, related data can be retrieved in a single API call, avoiding the n+1 problem and improving performance. For example, the following GraphQL query retrieves information about a user and their posts:

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

### Overfetching and Underfetching ###

Overfetching occurs when an API returns more data than a client needs, which can result in increased network overhead and slower performance. Underfetching occurs when an API does not return enough data for a client to complete its task, which can result in additional API calls and reduced performance.

In REST, overfetching and underfetching can be a common issue as the API often returns a fixed set of data for each resource. In GraphQL, the client has control over what data is retrieved, reducing the risk of overfetching or underfetching.

### Backward Compatibility ###

Backward compatibility is an important aspect of API design, as it allows for new versions of the API to be introduced without breaking existing clients. REST APIs are typically designed to be backwards compatible, while GraphQL has a built-in versioning system through its schema. This allows for new fields and types to be added without breaking existing clients, making it easier to evolve the API over time.

### Benefits of Schema and Type System ###

The schema and type system in GraphQL provide a clear and concise definition of the data that can be fetched and the operations that can be performed. This makes it easier for clients and servers to understand the API and reduces the risk of misunderstandings or errors. In addition, the type system helps to ensure that the data returned from the API is consistent and accurate.

In conclusion, GraphQL and REST are two popular API architectures that each have their own advantages and disadvantages. GraphQL provides a more efficient and flexible alternative to REST, while REST is a simple and well-established architecture that is widely adopted. Ultimately, the choice between GraphQL and REST will depend on the specific needs of the project and the preferences of the development team.