GraphQL vs REST: Which is Better for APIs?

In the world of web development, communication between a client (like a web or mobile app) and a server is crucial. Traditional REST APIs have been the go-to solution for many years, but GraphQL is emerging as a powerful alternative that offers more flexibility and efficiency. GraphQL is a query language for API and a server-side runtime engine used for data query and manipulation. It was developed by Facebook, and later made open source, and is now managed by GraphQL foundation hosted by Linux foundation. Many popular public APIs like Facebook, GitHub, Yelp, Shopify, and Google Directions API adopted GraphQL as the default way to access their services.

What is GraphQL?

GraphQL is an open-source query language and server-side runtime engine used to query and manipulate data using API. GraphQL uses declarative data fetching where the client can describe exactly what data it wants rather than getting a whole lot of data from a traditional API or using multiple end-points to give the client the required data. GraphQL is compatible with Java and frameworks like Spring, NodeJS, and Express and can also be used in Django.

Example of GraphQL

Suppose you are at the famous pizza shop to order some pizza. Imagine ordering a pizza and you get a fixed set of toppings on the pizza, and if you want something different, you need a new pizza with another predefined set of toppings. But you are looking for an option to order a custom pizza where you can specify the exact toppings you want. Similarly, when we use the REST API approach, it's the pizza with fixed toppings, and if we want a different set of toppings or say response then we need another API. But in the case of GraphQL, we can customize the response and ask for only what we need using a single endpoint.

Key Concepts in GraphQL

1. Schema

The schema is the soul of GraphQL. It defines the types of data that can be queried and how they relate to each other. It serves as a contract between the client and the server, outlining the structure of the data that can be requested.

2. Query

In GraphQL, a query is a request for specific data. Users can ask for just the information they require because it reflects the format of the response. The structure of the schema is directly correlated with the hierarchical nature of queries.

3. Mutation

While queries are used for fetching data, mutations are used for modifying data on the server. They allow clients to make changes to the data, such as adding a new record or updating an existing one.

GraphQL Query

Query is one of the operation of GraphQL where other two are Mutations, and Subscriptions. A GraphQL query is used to fetch data, GraphQL server executes the query and gives result.

The GraphQL query syntax is designed to be straightforward and expressive. Here is a breakdown of the basic syntax elements commonly used in GraphQL queries:

1. Basic Query Syntax

A basic query consists of the query keyword, with a set of fields to retrieve, and the field names

query {
  field1
  field2
  field3
}

2. Query with Arguments Syntax

Arguments can be included to filter or specify the data that is required

query {
  field(arg1: value1, arg2: value2) {
    subfield1
    subfield2
  }
}

Example: Which is Better for APIs?

Let's take the same pizza store example and understand how it works in GraphQL Query.

1. RESTful Approach

To order pizza in REST API approach, we may have to create two separate endpoints for pizzas and toppings. If you want a pizza with specific toppings, you have to make multiple requests.

Get Pizza Menu (GET /pizzas):

GET /pizzas

Server responds with a list of predefined pizzas and their toppings.

Select Pizza (GET /pizzas/{pizzaId}):

GET /pizzas/123

Fetch details for a specific pizza, but toppings are predefined and cannot be customized.

Place Order (POST /orders):

    POST /orders
    {
      "pizzaId": 123,
      "deliveryAddress": "123 GFG Office"
    }

Place an order with a predefined pizza and toppings.

2. GraphQL Approach

With GraphQL, You have the option to order a pizza with your customization.

Write a Query:

query {
  pizza(id: 123) {
    size
    crust
    toppings {
      name
    }
  }
}

Request the specific details you want for your pizza in a single query. A server-side query can be answered in a particular way with the use of arguments. It comes with a key:value pair and a field. It can either be a variable or a literal in the fields.

Get Custom Pizza:

{
  "data": {
    "pizza": {
      "size": "Large",
      "crust": "Thin",
      "toppings": [
        {"name": "Pepperoni"},
        {"name": "Mushrooms"},
        {"name": "Bell Peppers"}
      ]
    }
  }
}

Receive a custom-made pizza with the exact toppings you specified. Now you can order your customized pizza with your favourite toppings.

Differences Between GraphQL and REST API

Characteristics of GraphQL

1. Declarative Data

In GraphQL as it's tag line says "Ask for what you need, get exactly that" , clients can specify what data they require and will get the exact data they wanted. This helps in reducing over-fetching and under-fetching of data.

2. Single Endpoint

When GraphQL is used in the application, there is no need to create multiple endpoints to access the same type of data, GraphQL queries can dynamically fetch the required data. The single endpoint can handle various query and mutation.

3. Optimized Data Retrieval

GraphQL uses batch query system, where client can request multiple pieces of data in a single query optimizing the overall data retrieval by reducing number of requests sent to the server.

4. Flexibility

GraphQL is flexible in terms of data retrieval, fetches only required data. GraphQL is also flexible in terms of technology supporting backend services built on Java, NodeJS, and others.

Applications of GraphQL

Web and Mobile Applications

GraphQL is widely used in web and mobile app development where efficient data retrieval and flexible queries are ofetn required. It allows frontend developers to request only for the data needed which improves performance and reduces over-fetching or under-fetching of data.

Microservices Architecture

In a microservices architecture, where applications are made of multiple independent services, GraphQL can act as a unified interface for clients to fetch data from various microservices. This simplifies the communication between services and provide a single endpoint for clients.

Conclusion

Compared to conventional REST APIs, GraphQL offers a more effective and adaptable substitute, enabling developers to create better apps. GraphQL enhances client-server communication by enabling clients to define their data requirements, which leads to more efficient and effective applications. Understanding and utilizing GraphQL is a useful skill as you move ahead towards advance in web development since it will improve your capacity to design responsive, and effective applications.

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