使用 Node.js 构建 Restful CRUD API

CRUD API 是什么意思？

CRUD 范式代表四种原始数据库操作，即CREATE、、和。READUPDATEDELETE

所以，我们所说的“API”指的CRUD API是能够从数据库中获取、和实体的 API create。read在update本delete例中，实体是员工。

让我们开始吧

API 端点如下

方法	网址	描述
得到	API/员工	获取所有员工
得到	api/员工/id	获取特定员工
邮政	API/员工	创建新员工
放	api/员工/id	更新现有员工
删除	api/员工/id	删除现有员工

我们创建存储库并安装依赖项。
入口点是 server.js 文件。

 mkdir express-api
 cd express-api
 npm init
 npm install express helmet morgan body-parser monk joi dotenv --save 
 npm install nodemon --save-dev

关于套餐

express：它是一个最小且灵活的 Node.js Web 应用程序框架。helmet
：它有助于保护 express 应用程序中的 HTTP 标头。morgan
：它是 Node 的 HTTP 请求记录器中间件。js
body-parser：它负责解析传入的请求主体。monk
：一个微小的层，为 MongoDB 的使用提供了实质性的可用性改进。joi
：它是一种对象模式描述语言和对象验证器。dotenv
：它从 .env 文件加载环境变量。nodemon
：当检测到目录中的文件更改时，它会自动重新启动节点应用程序。

设置 Express Web 服务器
./src/server.js

const express = require('express');
const morgan = require('morgan');
const helmet = require('helmet');
const bodyParser = require('body-parser');

require('dotenv').config();

const app = express();
const monk = require('monk');

app.use(helmet());
app.use(morgan('dev'));
app.use(bodyParser.json());

const port = process.env.PORT || 8080;
app.listen(port, () => {
  console.log(`Listening on port ${port}`);
});

创建并配置 .env 文件
。./.env
包含我们使用的所有环境变量。
TEST_DB_URL变量用于测试用例，以防止测试数据插入数据库。此外，您还可以指定所需的端口号。

DB_URL = localhost/my-employees
TEST_DB_URL = localhost/test-my-employees
PORT = 5000

./src/db/schema.js创建数据模式并定义属性必须遵循的
验证规则。namejob

const Joi = require('joi');

const schema = Joi.object({
    name: Joi.string()
        .min(3)
        .max(30)
        .required(),
    job: Joi.string()
        .min(3)
        .max(30)
        .required(),
})

module.exports = schema;

./src/db/connection.js
连接数据库

const monk = require('monk');

let dbUrl = process.env.DB_URL;

if (process.env.NODE_ENV === 'test') {
  dbUrl = process.env.TEST_DB_URL;
}

const db = monk(dbUrl);

module.exports = db;

./src/middlewares/index.js
创建错误中间件来处理错误并给出正确的响应。

function notFound(req, res, next) {
    res.status(404);
    const error = new Error('Not Found', req.originalUrl);
    next(error);
}

function errorHandler(err, req, res, next){
    res.status(res.statusCode || 500);
    res.json({
        message: err.message,
        stack: err.stack
    });
}

module.exports = {
    notFound,
    errorHandler
}

我们导入./src/db/connection.js，./src/db/schema.js并将./src/middlewares/index.js文件放入./src/server.js

const express = require('express');
const morgan = require('morgan');
const helmet = require('helmet');
const bodyParser = require('body-parser');

const { notFound, errorHandler } = require('./middlewares');

require('dotenv').config();

const schema = require('./db/schema');
const db = require('./db/connection');
const employees = db.get('employees');

const app = express();

app.use(helmet());
app.use(morgan('dev'));
app.use(bodyParser.json());

app.use(notFound);
app.use(errorHandler);

const port = process.env.PORT || 8080;
app.listen(port, () => {
  console.log(`Listening on port ${port}`);
});

现在，我们对 API 端点进行编码

const express = require('express');
const morgan = require('morgan');
const helmet = require('helmet');
const bodyParser = require('body-parser');

const { notFound, errorHandler } = require('./middlewares');

require('dotenv').config();

const schema = require('./db/schema');
const db = require('./db/connection');
const employees = db.get('employees');

const app = express();

app.use(helmet());
app.use(morgan('dev'));
app.use(bodyParser.json());

/* Get all employees */
app.get('/', async (req, res, next) => {
    try {
        const allEmployees = await employees.find({});
        res.json(allEmployees);
    } catch(error) {
        next(error);
    }
});

/* Get a specific employee */
app.get('/:id', async (req, res, next) => {
    try {
        const { id } = req.params;
        const employee = await employees.findOne({
            _id: id
        });

        if(!employee) {
            const error = new Error('Employee does not exist');
            return next(error);
        }

    res.json(employee);
    } catch(error) {
        next(error);
    }
});

/* Create a new employee */
app.post('/', async (req, res, next) => {
    try {
        const { name, job } = req.body;
        const result = await schema.validateAsync({ name, job });

        const employee = await employees.findOne({
            name,
        })

        // Employee already exists
        if (employee) {
            res.status(409); // conflict error
            const error = new Error('Employee already exists');
            return next(error);
        } 

        const newuser = await employees.insert({
            name,
            job,
        });

        console.log('New employee has been created');
        res.status(201).json(newuser);
    } catch(error) {
        next(error);
    }
});

/* Update a specific employee */
app.put('/:id', async (req, res, next) => {
    try {
        const { id } = req.params;
        const { name, job } = req.body;
        const result = await schema.validateAsync({ name, job });
        const employee = await employees.findOne({
            _id: id
        });

        // Employee does not exist
        if(!employee) {
            return next();
        }

        const updatedEmployee = await employees.update({
            _id: id,
            }, {  
            $set: result},
            { upsert: true }
        );

        res.json(updatedEmployee);
    } catch(error) {
        next(error);
    }
});

/* Delete a specific employee */
app.delete('/:id', async (req, res, next) => {
    try {
        const { id } = req.params;
        const employee = await employees.findOne({
            _id: id
        });

        // Employee does not exist
        if(!employee) {
            return next();
        }
        await employees.remove({
            _id: id
        });

        res.json({
            message: 'Success'
        });

    } catch(error) {
        next(error);
    }
});

app.use(notFound);
app.use(errorHandler);

const port = process.env.PORT || 8080;
app.listen(port, () => {
  console.log(`Listening on port ${port}`);
});

我们进入package.json文件并用以下内容替换脚本部分

"scripts": {
    "start": "node src/server.js",
    "dev": "nodemon src/server.js"
  },

该命令npm start启动 Node.js 应用程序，该命令npm run dev启动 Node.js 应用程序，唯一的区别是我们所做的任何更改都将自动由 nodemon 监控。

我们“分割”./src/server.js并创建./src/app.js文件。

./src/app.js

const express = require('express');
const morgan = require('morgan');
const helmet = require('helmet');
const bodyParser = require('body-parser');

const { notFound, errorHandler } = require('./middlewares');

require('dotenv').config();

const schema = require('./db/schema');
const db = require('./db/connection');
const employees = db.get('employees');

const app = express();

app.use(helmet());
app.use(morgan('dev'));
app.use(bodyParser.json());

/* Get all employees */
app.get('/', async (req, res, next) => {
    try {
        const allEmployees = await employees.find({});
        res.json(allEmployees);
    } catch(error) {
        next(error);
    }
});

/* Get a specific employee */
app.get('/:id', async (req, res, next) => {
    try {
        const { id } = req.params;
        const employee = await employees.findOne({
            _id: id
        });

        if(!employee) {
            const error = new Error('Employee does not exist');
            return next(error);
        }

    res.json(employee);
    } catch(error) {
        next(error);
    }
});

/* Create a new employee */
app.post('/', async (req, res, next) => {
    try {
        const { name, job } = req.body;
        const result = await schema.validateAsync({ name, job });

        const employee = await employees.findOne({
            name,
        })

        // Employee already exists
        if (employee) {
            res.status(409); // conflict error
            const error = new Error('Employee already exists');
            return next(error);
        } 

        const newuser = await employees.insert({
            name,
            job,
        });

        console.log('New employee has been created');
        res.status(201).json(newuser);
    } catch(error) {
        next(error);
    }
});

/* Update a specific employee */
app.put('/:id', async (req, res, next) => {
    try {
        const { id } = req.params;
        const { name, job } = req.body;
        const result = await schema.validateAsync({ name, job });
        const employee = await employees.findOne({
            _id: id
        });

        // Employee does not exist
        if(!employee) {
            return next();
        }

        const updatedEmployee = await employees.update({
            _id: id,
            }, {  
            $set: result},
            { upsert: true }
        );

        res.json(updatedEmployee);
    } catch(error) {
        next(error);
    }
});

/* Delete a specific employee */
app.delete('/:id', async (req, res, next) => {
    try {
        const { id } = req.params;
        const employee = await employees.findOne({
            _id: id
        });

        // Employee does not exist
        if(!employee) {
            return next();
        }
        await employees.remove({
            _id: id
        });

        res.json({
            message: 'Success'
        });

    } catch(error) {
        next(error);
    }
});

app.use(notFound);
app.use(errorHandler);

module.exports = app;

./src/server.js

const app = require('./app');

const port = process.env.PORT || 8080;
app.listen(port, () => {
  console.log(`Listening on port ${port}`);
});

最后一步是重构我们的代码并创建./src/routes/employees。

./src/routes/employees.js

const express = require('express');
const schema = require('../db/schema');
const db = require('../db/connection');

const employees = db.get('employees');

const router = express.Router();

/* Get all employees */
router.get('/', async (req, res, next) => {
  try {
    const allEmployees = await employees.find({});
    res.json(allEmployees);
  } catch (error) {
    next(error);
  }
});

/* Get a specific employee */
router.get('/:id', async (req, res, next) => {
  try {
    const { id } = req.params;
    const employee = await employees.findOne({
      _id: id,
    });

    if (!employee) {
      const error = new Error('Employee does not exist');
      return next(error);
    }

    res.json(employee);
  } catch (error) {
    next(error);
  }
});

/* Create a new employee */
router.post('/', async (req, res, next) => {
  try {
    const { name, job } = req.body;
    const result = await schema.validateAsync({ name, job });

    const employee = await employees.findOne({
      name,
    });

    // Employee already exists
    if (employee) {
      const error = new Error('Employee already exists');
      res.status(409); // conflict error
      return next(error);
    }

    const newuser = await employees.insert({
        name,
        job,
    });

    res.status(201).json(newuser);
  } catch (error) {
    next(error);
  }
});

/* Update a specific employee */
router.put('/:id', async (req, res, next) => {
  try {
    const { id } = req.params;
    const { name, job } = req.body;
    const result = await schema.validateAsync({ name, job });
    const employee = await employees.findOne({
      _id: id,
    });

    // Employee does not exist
    if (!employee) {
      return next();
    }

    const updatedEmployee = await employees.update({
      _id: id,
    }, { $set: result },
    { upsert: true });

    res.json(updatedEmployee);
  } catch (error) {
    next(error);
  }
});

/* Delete a specific employee */
router.delete('/:id', async (req, res, next) => {
  try {
    const { id } = req.params;
    const employee = await employees.findOne({
      _id: id,
    });

    // Employee does not exist
    if (!employee) {
      return next();
    }
    await employees.remove({
      _id: id,
    });

    res.json({
      message: 'Employee has been deleted',
    });
  } catch (error) {
    next(error);
  }
});

module.exports = router;

./src/app.js文件如下所示

const express = require('express');
const morgan = require('morgan');
const helmet = require('helmet');
const bodyParser = require('body-parser');

const { notFound, errorHandler } = require('./middlewares');

const app = express();

require('dotenv').config();

app.use(helmet());
app.use(morgan('dev'));
app.use(bodyParser.json());

const employees = require('./routes/employees');

app.use('/api/employees', employees);

app.use(notFound);
app.use(errorHandler);

module.exports = app;

您可以在我的 GitHub 存储库express-api中查看整个项目

文章来源：https://dev.to/zagaris/build-a-restful-crud-api-with-node-js-2334

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使用 Node.js 构建 Restful CRUD API

使用 Node.js 构建 Restful CRUD API

目录

CRUD API 是什么意思？

让我们开始吧

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