Learn to build APIs with PHP and GraphQL

With the development of Internet technology, the architecture of front-end and back-end separation has become the mainstream of Web development. In an architecture where the front and back ends are separated, API is an important bridge connecting the front and back ends. When building APIs, PHP and GraphQL, as two popular technology frameworks, are widely favored by developers. This article will introduce how to build an API using PHP and GraphQL.

1. PHP Building API

PHP is an open source scripting language widely used in Web development. Its application scope covers website development, database applications, log processing, image processing and other aspects. . When building an API, PHP can be used as a back-end language to transmit data to the front-end by interacting with the front-end.

1. Install PHP

First, we need to install the PHP environment. You can check whether PHP has been installed locally by entering the following command in the command line window:

php -v

If the PHP version number is displayed, it means that the PHP environment has been installed. If it is not installed, you need to go to [PHP official website](https://www.php.net/) to download and install it.

2. Select a framework

In PHP, there are multiple frameworks to choose from, such as Laravel, Symfony, Zend, etc. Among them, Laravel is a framework widely used in PHP web application development. Following are the steps to create an API using Laravel framework.

3. Create project

You can create a Laravel project named "myapp" locally by entering the following command in the command line window:

composer create-project laravel/laravel myapp --prefer-dist

4. Create Controller

Before creating the API, you need to create a controller. You can create a controller by entering the following command:

php artisan make:controller MyController

In MyController, you can write the business logic code of the API. For example, in MyController, you can write an API code to query all user information as follows:

public function getAllUsers()
{
    $users = User::all(); // 查询所有用户信息
    return response()->json($users); // 返回JSON格式的用户信息
}

Among them, User represents the user model, which can be defined through Laravel's Eloquent ORM.

5. Routing

In Laravel, API requests can be processed through routing. You can use the following code to add routing to the API you just created:

Route::get('/users', 'MyController@getAllUsers');

Among them, '/users' represents the URL address of the request, and 'MyController@getAllUsers' represents the controller method that handles the request.

6. Run the project

Finally, you can run the created Laravel project through the following command:

php artisan serve

By accessing 'http://localhost: 8000/users' to view the JSON format data of all user information.

2. GraphQL construction API

Compared with RESTful API, the advantage of GraphQL is that it allows the front end to initiate a precise query to obtain the required data, reducing the pressure of database query. Below we introduce how to use GraphQL to build an API.

1. Installing GraphQL

GraphQL can be started as an independent API service, so it needs to be installed first. GraphQL can be installed through the following command:

npm install graphql-yoga

2. Create Schema

In GraphQL, you need to write a Schema to define the API interface. Schema describes the type of each type of data, the return type of each field, and the input and output parameters of the method. For example, in this Schema, we need to define a User type and an interface for querying all user information. The code is as follows:

const typeDefs = `
  type User {
    id: ID!
    name: String!
    email: String
  }
  type Query {
    getAllUsers: [User]!
  }
`;

3. Writing Resolver

Resolver implements each field in the Schema and describes how to obtain data. In this example, the Resolver code for querying all user information is as follows:

const resolvers = {
  Query: {
    getAllUsers: async () => {
      const users = await User.find();
      return users;
    },
  },
};

4. Run the project

Finally, run the GraphQL service. You can start the service with the following command ：

const { GraphQLServer } = require('graphql-yoga');

const server = new GraphQLServer({ typeDefs, resolvers });
server.start({ port: 4000 }, () =>
  console.log(`Server is running on localhost:4000`)
);

By accessing 'http://localhost:4000/graphql', you can use the GraphQL Playground tool to test the API.

Conclusion

This article introduced how to build an API using PHP and GraphQL. In PHP, you can use the Laravel framework to create APIs, and in GraphQL, you can use graphql-yoga. By studying the content of this article, I believe that readers have a certain understanding of how to use PHP and GraphQL to build APIs, and can try to apply them in actual projects.

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