MongoDB

A basis,

1. Configure the environment

Start by installing MongoDB and Node.js

NPM install mongoose

elegant mongodb object modeling for node.js

Mongoose can be understood as a tool that can connect to mongoDB database in Node

npm install mongoose --save
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2. Easy to use

Introduce Mongoose in JS file and establish connection with database

// server.js
const mongoose = require('mongoose');
mongoose.connect('mongodb://localhost:27017/express-test')
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Suppose we have multiple products and want to record each product in the database, and each product has a Tittle attribute

// server.js 
// Define the product model
const Product = mongoose.model('Product'.new mongoose.Schema({
  title: String,}))Copy the code

To test, use the insertMany method to insert multiple pieces of data into the database. Note that the method needs to be commented out after it is executed only once

// server.js
// Product.insertMany([
// {title: 'product 1'},
// {title: 'product 2'},
// {title: 'product 3'},
// ])
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Use the find method to query all data in the database

// server.js
app.get('/products'.async function(req, res){
  res.send(await Product.find())
})
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The complete code is

const express = require('express');

const app = express();

const mongoose = require('mongoose');
mongoose.connect('mongodb://localhost:27017/express-test')
// Define the product model
const Product = mongoose.model('Product'.new mongoose.Schema({
  title: String,}))// Product.insertMany([
// {title: 'product 1'},
// {title: 'product 2'},
// {title: 'product 3'},
// ])


app.get('/'.function(req, res){
  res.send({ page: 'home' })
})

app.get('/about'.function(req, res){
  res.send({ page: 'About Us' })
})

app.get('/products'.async function(req, res){
  res.send(await Product.find())
})

app.listen(3000.() = > {
  console.log('App listening on port 3000! ');
})
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The results of

Second, the query

1. Product list page interface

Query all data

/** * find Find all data */
app.get('/products'.async function(req, res){
  const data = await Product.find();
  res.send(data)
})
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Paging scenarios

/** ** limit(num) limits the number of pieces of data returned * skip and limit can be used together for paging */
app.get('/products'.async function(req, res){
    const data = await Product.find().skip(1).limit(2);
    res.send(data)
})
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Specify search criteria

/** * where query criteria */
app.get('/products'.async function(req, res){
    const data = await Product.find().where({
        title: Products' 2 '
    });
    res.send(data)
})
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The sorting

/** * sort sort 1: sort -1: sort */
app.get('/products'.async function(req, res){
    const data = await Product.find().sort({_id: -1})
    res.send(data)
})
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2. Product details page interface

/** * findById is an object, not an array */
app.get('/products/:id'.async function(req, res){
  const data = await Product.findById(req.params.id);
  res.send(data);
})
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New and POST requests

Suppose we want to write a new entry of product data, how do we write an interface for entry of product data?

1. REST Client plug-in

Install the REST Client plug-in in Vscode, which can initiate various HTTP requests in code

Create a new file in the root directory with the suffix HTTP, such as test.http

• Write the Request code in the file, click Send Request, you can see the Request result on the right side
• Each request requires# # #separate
• You can use@Define variables{{}}Reference variables

2. A POST request

To the test. HTTP file

POST {{uri}}products
Content-Type: Application /json {"title": "product 4"}Copy the code

3. Product input interface

To the server.js file

app.post('/products'.async function(req, res){
  const data = req.body; // POST requests submitted data
  const product = await Product.create(data); // Create a product
  res.send(product); // Send out the product data
})
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Because the POST request sends JSON data, it needs to be written in the server.js file

// Allow Express to process submitted JSON data
app.use(express.json())
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Click Send Request for input product Request to obtain a piece of product dataClick Send Request of the product list Request and find that the product data has been successfully entered

Modify and PUT requests

If we want to modify a piece of product data, such as product title, how do we write a modify product data interface?

Server. The js file

/** * Modify the product data interface */
app.put('/products/:id'.async function(req, res){
  / / to find
  const product = await Product.findById(req.params.id);
  / / assignment
  product.title = res.body.title;
  / / save
  await product.save();
  / / return
  res.send(product);
})
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To the test. HTTP file

PUT {{uri}}products/61372a06cc69aac0beb6c606
Content-Type: Application /json {"title": "product 5_ modify"}Copy the code

Click Send Request to Send the product modification Request to product 5titleModify to “Product 5_ Modified”

DELETE and DELETE requests

Write/delete product data interface in server.js file

app.delete('/products/:id'.async function(req, res){
  / / to find
  const product = await Product.findById(req.params.id);
  / / delete
  await product.remove();
  // Returns a status indicating that the execution succeeded
  res.send({
    success: true
  });
})
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To the test. HTTP file

DELETE {{uri}}products/61372a06cc69aac0beb6c606
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Click Send Request to Send a Request to delete product 5