Overview of GraphQL

What is GraphQL?

GraphQL is a powerful query language and runtime for APIs that was developed by Facebook in 2012, and then released as open-source in 2015. GraphQL was created with the primary goal of enabling more efficient and flexible communication between clients and servers compared to traditional REST APIs.

With REST APIs, clients often face issues like over-fetching or under-fetching of data. This means that the client either retrieves more data than necessary, or has to make multiple requests to gather the required information. GraphQL, on the other hand, allows clients to request the exact data they need and receive responses in a JSON format. This way, clients avoid fetching unnecessary information, saving both time and resources.

GraphQL is particularly valuable when creating headless storefronts with modern frontend frameworks like React, Angular, or Vue.js, as well as Progressive Web Applications (PWAs) such as Magento’s PWA Studio. GraphQL can provide fine-grained control over the data each of these headless apps consume, which can provide more tailored responses and faster performance compared to traditional REST APIs.

GraphQL in Magento 2

Starting from version 2.3, Magento 2 introduced support for GraphQL, offering a powerful and flexible alternative to traditional REST and SOAP APIs for frontend development. This new approach benefits both the development and maintenance of Magento stores, especially when dealing with complex and custom features.

With GraphQL, developers working on a headless frontend of a Magento store can request specific data from the backend of their Magento instance without having to create custom REST endpoints or fetch unnecessary information. Additionally, GraphQL enables frontend developers to easily change the data requirements without modifying the server code, increasing development efficiency and reducing the risk of data inconsistencies.

GraphQL Essentials

There are three main concepts are central to understanding GraphQL: schemas, queries, and mutations.

1. Schemas: A GraphQL server relies on a schema to define the structure of data that clients can request. The schema acts as a contract between the client and the server, ensuring that the server only returns the data described in the schema, and that clients only request data that the server can provide.
2. Queries: Queries in GraphQL are used to request data from the server’s schema, similar to GET requests in REST APIs. The client specifies the fields and nested data it wants to retrieve, as well as any filters or sorting criteria. The server then processes the request and returns the desired data in a structured JSON format that is tailored to the client's needs.
3. Mutations: Mutations are utilized to create, update, or delete data on the server. They function similarly to POST, PUT, PATCH, and DELETE requests in REST APIs. Just like with queries, the client specifies the data it wants to modify along with the intended operation. The server processes the mutation, performs the appropriate action, and returns the result to the client.

The schema is crafted using the GraphQL Schema Definition Language (SDL) which describes types, queries, mutations, and any other structures that the API supports. Additionally, the schema provides self-documenting capabilities, offering valuable information about available fields, their relationships, and the types of data they represent.