Should I use GraphQL over REST? With PHP Examples

REST is well-established and widely used, while GraphQL provides a more flexible and powerful way to query data from APIs. In this article, we'll explore the differences between REST and GraphQL, and discuss how to choose the right technology for your project.

What is REST?

REST is a well-established and widely used standard for building APIs. It is simple to understand and easy to implement, and there are many existing libraries and tools available to work with REST APIs. RESTful APIs typically use HTTP methods (GET, POST, PUT, DELETE) to perform CRUD (Create, Read, Update, Delete) operations on resources.

The origin of REST (Representational State Transfer) can be traced back to a dissertation written by Roy Fielding in 2000, while he was a graduate student at the University of California, Irvine. Fielding's dissertation, entitled "Architectural Styles and the Design of Network-based Software Architectures", proposed a set of architectural principles and constraints for building web-based systems that became known as REST.

Fielding's dissertation was influenced by previous work in software architecture, particularly the notion of architectural styles, which are patterns of structural organization and communication that can be applied to software systems. REST is based on the client-server model and the HTTP protocol, and is designed to support a scalable and interoperable architecture for web-based systems.

REST has since become a popular and widely adopted architectural style for building web services, and is supported by many programming languages and frameworks. Its simplicity and flexibility make it well-suited to a wide range of applications, from small-scale systems to large-scale enterprise applications.

What is GraphQL?

GraphQL, on the other hand, is a newer technology that provides a more flexible and powerful way to query data from APIs. With GraphQL, clients can request exactly the data they need and get it in a single request. This can lead to better performance and reduced network overhead compared to REST. Additionally, GraphQL allows for better versioning and documentation of APIs.

GraphQL was developed by Facebook in 2012, as a solution to some of the challenges they faced while building mobile applications that relied on data from various back-end services. At the time, Facebook was using a REST-based architecture, which required multiple API requests to different endpoints to fetch all the necessary data. This resulted in poor performance, as well as increased network latency and complexity.

To address these issues, a team at Facebook, led by Lee Byron, began working on a new query language that would allow clients to request only the data they needed, in a single request. This language became known as GraphQL, and it was initially released as an internal tool for Facebook's mobile app development.

In 2015, Facebook open-sourced GraphQL, making it available for use by other organizations. Since then, GraphQL has gained widespread adoption and support from the developer community, and is now used by many companies and organizations, including GitHub, Shopify, and The New York Times.

GraphQL's popularity can be attributed to its flexibility, power, and ease of use. It allows clients to specify exactly the data they need, which can reduce network overhead and improve performance. Additionally, GraphQL's type system and schema provide a clear and well-documented API, which can help to reduce errors and improve maintainability.

Should I use GraphQL over REST?

The decision to use RESTful or GraphQL depends on the specific needs and requirements of your project.

Here are some factors to consider when deciding between RESTful and GraphQL:

Data complexity

If your API deals with complex and deeply nested data, GraphQL can be a better choice, as it allows clients to request only the data they need in a single request. RESTful APIs may require multiple requests to retrieve all the necessary data.

Caching

RESTful APIs work well with caching, as they rely on HTTP caching mechanisms. GraphQL, on the other hand, requires more fine-grained control over caching, as the data returned in a GraphQL response can be highly specific to the client's needs.

Team size

If you have a large team working on the API, RESTful can be easier to understand and implement, as it has a simpler and more widely understood architecture. GraphQL can require more expertise and experience to implement effectively.

Existing infrastructure

If you already have a RESTful API in place and it meets your needs, it may not be necessary to switch to GraphQL. Similarly, if you are building a new API and have experience with RESTful architecture, it may make sense to stick with what you know.

API versioning

RESTful APIs can be versioned easily by creating new endpoints or using versioning in the URL. GraphQL, on the other hand, does not have a standard versioning mechanism, and may require more thought and planning to maintain backwards compatibility.

REST API - PHP Example

Here's an example of a simple REST API for managing a list of users using PHP and the Slim framework:

<?php

require_once 'vendor/autoload.php';

use Slim\Slim;
use Slim\Http\Request;
use Slim\Http\Response;

// Initialize Slim application
$app = new Slim();

// Initialize user data
$users = [
    ['id' => 1, 'name' => 'John', 'email' => 'john@example.com'],
    ['id' => 2, 'name' => 'Jane', 'email' => 'jane@example.com']
];

// Get all users
$app->get('/users', function (Request $request, Response $response, $args) use ($users) {
    return $response->withJson($users);
});

// Get a single user by ID
$app->get('/users/{id}', function (Request $request, Response $response, $args) use ($users) {
    $id = $args['id'];
    foreach ($users as $user) {
        if ($user['id'] == $id) {
            return $response->withJson($user);
        }
    }
    return $response->withStatus(404);
});

// Create a new user
$app->post('/users', function (Request $request, Response $response, $args) use ($users) {
    $data = $request->getParsedBody();
    $user = ['id' => count($users) + 1, 'name' => $data['name'], 'email' => $data['email']];
    $users[] = $user;
    return $response->withJson($user)->withStatus(201);
});

// Update an existing user
$app->put('/users/{id}', function (Request $request, Response $response, $args) use ($users) {
    $id = $args['id'];
    $data = $request->getParsedBody();
    foreach ($users as &$user) {
        if ($user['id'] == $id) {
            $user['name'] = $data['name'];
            $user['email'] = $data['email'];
            return $response->withJson($user);
        }
    }
    return $response->withStatus(404);
});

// Delete an existing user
$app->delete('/users/{id}', function (Request $request, Response $response, $args) use ($users) {
    $id = $args['id'];
    foreach ($users as $key => $user) {
        if ($user['id'] == $id) {
            unset($users[$key]);
            return $response->withStatus(204);
        }
    }
    return $response->withStatus(404);
});

// Run Slim application
$app->run();

This API defines five routes for managing users:

GET /users: returns a list of all users
GET /users/{id}: returns a single user by ID
POST /users: creates a new user
PUT /users/{id}: updates an existing user by ID
DELETE /users/{id}: deletes an existing user by ID

Requests to these routes can be made using HTTP methods and URLs, such as:

GET http://localhost/users
GET http://localhost/users/1
POST http://localhost/users with { "name": "Alice", "email": "alice@example.com" } in the request body
PUT http://localhost/users/1 with { "name": "John Doe", "email": "john.doe@example.com" } in the request body
`DELETE http://localhost/users/

GraphQL API - PHP Example

Here's an example of how to create a simple GraphQL API using PHP and the webonyx/graphql-php library:

<?php

require_once 'vendor/autoload.php';

use GraphQL\Type\Schema;
use GraphQL\Type\Definition\Type;
use GraphQL\Type\Definition\ObjectType;
use GraphQL\GraphQL;

// Initialize user data
$users = [
    ['id' => 1, 'name' => 'John', 'email' => 'john@example.com'],
    ['id' => 2, 'name' => 'Jane', 'email' => 'jane@example.com']
];

// Define GraphQL types
$userType = new ObjectType([
    'name' => 'User',
    'fields' => [
        'id' => Type::int(),
        'name' => Type::string(),
        'email' => Type::string()
    ]
]);

$queryType = new ObjectType([
    'name' => 'Query',
    'fields' => [
        'user' => [
            'type' => $userType,
            'args' => [
                'id' => Type::int()
            ],
            'resolve' => function ($root, $args) use ($users) {
                foreach ($users as $user) {
                    if ($user['id'] == $args['id']) {
                        return $user;
                    }
                }
                return null;
            }
        ],
        'users' => [
            'type' => Type::listOf($userType),
            'resolve' => function () use ($users) {
                return $users;
            }
        ]
    ]
]);

// Define GraphQL schema
$schema = new Schema([
    'query' => $queryType
]);

// Handle GraphQL request
$input = file_get_contents('php://input');
$variables = json_decode(file_get_contents('php://input'), true)['variables'] ?? null;
$query = json_decode($input, true)['query'] ?? '';

try {
    $result = GraphQL::executeQuery($schema, $query, null, null, $variables);
    $output = $result->toArray();
} catch (\Exception $e) {
    $output = [
        'errors' => [
            ['message' => $e->getMessage()]
        ]
    ];
}

// Return JSON response
header('Content-Type: application/json');
echo json_encode($output);

This code defines a simple GraphQL schema with two queries: user and users. The user query takes an id argument and returns a single user by ID, while the users query returns a list of all users. The webonyx/graphql-php library is used to execute the GraphQL queries and return the results in JSON format.

To use this API, you can send a GraphQL query using a tool like GraphiQL or Postman:

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

This query would return a single user with ID 1, along with a list of all users in the users field. The response would be returned in JSON format:

{
  "data": {
    "user": {
      "id": 1,
      "name": "John",
      "email": "john@example.com"
    }
  }
}

Common mistakes using GraphQL

Here are some of the most common mistakes that developers make when working with GraphQL.

Over-fetching or under-fetching data

One of the key benefits of GraphQL is that clients can request only the data they need. However, it's easy to over-fetch or under-fetch data by not specifying the exact data requirements in a query. Over-fetching can result in unnecessary network overhead and slower performance, while under-fetching can result in incomplete or inaccurate data.

Inefficient queries

Inefficient queries can also result in slow performance and increased network overhead. It's important to ensure that queries are well-optimized and use the appropriate data types and structures.

Security vulnerabilities

As with any API, GraphQL APIs can be vulnerable to a range of security threats, including injection attacks, DoS attacks, and unauthorized access. It's important to follow best practices for API security, including implementing strong authentication and authorization mechanisms, input validation, rate limiting, and monitoring and logging.

Syntax errors

Syntax errors occur when the GraphQL query is malformed or does not conform to the GraphQL syntax rules. These errors can prevent the query from being executed, and can result in confusing error messages or unexpected behavior. Common syntax errors include misspelled field names, missing curly braces, or incorrect use of GraphQL keywords.

Validation errors

Validation errors occur when the GraphQL query is well-formed, but does not conform to the schema or type system of the API. These errors can occur when the query requests an invalid or non-existent field, or when the query requests a field that is not allowed for the specified object type. Validation errors can also occur when the query requests a field with the wrong type, or when the query includes arguments that are not valid for the specified field.

Poorly-designed schemas

The schema is a critical component of a GraphQL API, as it defines the structure and types of data that can be queried. A poorly-designed schema can make it difficult for clients to use the API effectively, or result in inefficient or incorrect queries.

Lack of testing

As with any software development project, testing is critical for ensuring the quality and stability of a GraphQL API. It's important to test all aspects of the API, including queries, mutations, subscriptions, and security mechanisms.

Will GraphQL replace REST API?

It's unlikely that GraphQL will completely replace REST, as both technologies have their own strengths and weaknesses and are suited for different use cases.

REST has been around for a long time and is widely used and understood by developers. It is a mature technology with a simple and well-understood architecture, and is well-suited for simple APIs that require basic CRUD (Create, Read, Update, Delete) operations. REST is also well-supported by many programming languages and frameworks, and is used extensively by many organizations and services.

GraphQL, on the other hand, is a newer technology that provides more flexibility and power in querying data from APIs. It is particularly useful for large and complex APIs with a high degree of variability in the data needed by clients. GraphQL's type system and schema provide a clear and well-documented API, which can help to reduce errors and improve maintainability.

Both REST and GraphQL have their own use cases, and it's likely that they will continue to coexist and be used in different scenarios. While GraphQL has gained popularity in recent years, it is not necessarily a replacement for REST, but rather a complementary technology that provides a different set of tools and capabilities.

Updated May 1, 2023