Nodejs operation mongodb third (about the use of schema)

1. `schema`Default parameters

Many times we will set default parameters, and default this value when not inserting data

1. Packaged connection database module

// 第一步
const mongoose = require('mongoose');

// 第二步连接数据库
mongoose.connect('mongodb://root:123456@localhost/nest_cms', {
      
       useNewUrlParser: true }, (err) => {
      
      
    if (err) {
      
      
        console.log('连接错误');
        return;
    }
    console.log('mongodb连接成功');
});

module.exports = mongoose;

2. Define the usermodel

const mongoose = require('./db');

const UserSchema = mongoose.Schema({
      
      
    name: String,
    age: Number,
    status: {
      
       // 默认参数
        type: Number,
        default: 1,
    }
})

module.exports=mongoose.model('User',UserSchema,'user');

3. Use a defined model

const UserModel = require('./model/user');

var user = new UserModel({
      
      
    name: '李四',
    age: 20
});
user.save((err) => {
      
      
    if (err) {
      
      
        console.log('保存数据错误')
    }
    console.log('保存数据成功');
});

4. Query data returned

[ {
      
       status: 1,
    _id: 5e0fdb9d6e124d1f3096d9f3,
    name: '张三',
    age: 20,
    __v: 0 },
  {
      
       status: 1, // 默认插入的是1
    _id: 5e0fdbca98ff701f9006afcd,
    name: '李四',
    age: 20,
    __v: 0 } ]

Two, the `mongoose`predefined pattern decorator

1. The mongoosebuilt-in predefined modifiers mainly include
- lowercase
- uppercase
- trim

2. schemaUsed in

const mongoose = require('./db');

const UserSchema = mongoose.Schema({
      
      
    name: {
      
      
        type: String,
        trim: true,
    },
    age: Number,
    message1: {
      
      
        type: String,
        lowercase: true,
    },
    message2: {
      
      
        type: String,
        uppercase: true,
    },
    status: {
      
      
        type: Number,
        default: 1,
    }
})

module.exports=mongoose.model('User',UserSchema,'user');

Three, `mogoose`the predefined `set`and `get`modifiers

We can also use set(recommended) modifiers to format the data when adding data. You can also use get(not recommended) to format the data when the instance gets the data, not when querying the data.

1. Definitionschema

const mongoose = require('./db');

const NewSchema = mongoose.Schema({
      
      
    title: {
      
      
        type: String,
        trim: true,
    },
    author: String,
    avatar: {
      
      
        type: String,
        set(url) {
      
      
            if (!url) {
      
      
                return '';
            }
            if (url.indexOf('http://') !=0 && url.indexOf('https://') !=0) {
      
      
                url = 'http://' + url;
            }
            return url;
        }
    }
})

module.exports = mongoose.model('New', NewSchema, 'new');

2. Insert a piece of data

const NewModel = require('./model/new');

const news = new NewModel({
      
      
    title: '文章一',
    author: '张三',
    avatar: 'xx.png'
})

news.save();

3. Query results

{
      
      
    "_id" : ObjectId("5e0fe0b971428227107241c1"),
    "title" : "文章一",
    "author" : "张三",
    "avatar" : "http://xx.png",
    "__v" : 0
}

Four, `mongodb`the index in

1. The role of index

An index is a structure that sorts the values of one or more columns in a database table, which allows us to query the database
faster. MongoDBThe index is almost exactly the same as the traditional relational database, which also includes some basic
query optimization techniques.

2. Create an index

db.user.ensureIndex({
      
      字段:1}) // 普通索引

3. Get the index
```
db.user.getIndexes()
```

4. Delete the index

db.user.dropIndex({
      
      字段:1})

5. Composite index

// 数字 1 表示 username 键的索引按升序存储，-1 表示 age 键的索引按照降序方式存储
db.user.ensureIndex({
      
      "username":1, "age":-1})

6. Unique index

db.user.ensureIndex({
      
      "userid":1},{
      
      "unique":true})

Five `mongoose`of `schema`creating an index

1. Define schemaa unique index when defining

const mongoose = require('./db');

const UserSchema = mongoose.Schema({
      
      
    name: {
      
      
        type: String,
        trim: true,
        unique: true, // 创建唯一索引
    },
    age: Number,
    message1: {
      
      
        type: String,
        lowercase: true,
    },
    message2: {
      
      
        type: String,
        uppercase: true,
    },
    status: {
      
      
        type: Number,
        default: 1,
    }
})

module.exports=mongoose.model('User',UserSchema,'user');

Six, the use of time

1. schemaUse timestampsattributes in the definition

var mongoose = require('./db.js');

var UserSchema = new mongoose.Schema({
      
      
  name: String,
  age: Number,
  mobile: Number,
  status: {
      
      
    type: Number,
    default: 1
  }
}, {
      
      
  //设置时间戳
  timestamps: true
});

module.exports = mongoose.model('User', UserSchema, 'user');

2. Create data

const UserModel = require('./model/user');

const user = new UserModel({
      
      
  name: '王五',
  age: 20,
  mobile: 100,
  status: 0
});

user.save();

3. Query the data after creation

{
      
      
    "_id" : ObjectId("5e12a7f6c63086a54eed0a47"),
    "status" : 0,
    "name" : "王五",
    "age" : 20,
    "mobile" : 100,
    "createdAt" : ISODate("2020-01-06T03:22:30.336Z"), // 与系统默认时间相差8小时
    "updatedAt" : ISODate("2020-01-06T03:22:30.336Z"),
    "__v" : 0
}

4. Modify createdAtand updatedAtdisplay

var mongoose = require('./db.js');


var UserSchema = new mongoose.Schema({
      
      
  name: String,
  age: Number,
  mobile: Number,
  status: {
      
      
    type: Number,
    default: 1
  }
}, {
      
      
  //设置时间戳
  timestamps: {
      
      
    createdAt: 'created_at',
    updatedAt: "updated_at"
  }
});

module.exports = mongoose.model('User', UserSchema, 'user');

5. The created data

{
      
      
    "_id" : ObjectId("5e12ac19a1b9cfab59fbd913"),
    "status" : 0,
    "name" : "马六",
    "age" : 20,
    "mobile" : 100,
    "created_at" : ISODate("2020-01-06T03:40:09.560Z"),
    "updated_at" : ISODate("2020-01-06T03:40:09.560Z"),
    "__v" : 0
}

6. Modify the data

UserModel.updateOne({
      
       _id: '5e12ac19a1b9cfab59fbd913' }, {
      
       name: '王小二' }, (err, docs) => {
      
      
  if (err) {
      
      
    console.log('修改数据错误', err);
    return;
  }
  console.log(docs)
})

7. Modified data

{
      
      
    "_id" : ObjectId("5e12ac19a1b9cfab59fbd913"),
    "status" : 0,
    "name" : "王小二",
    "age" : 20,
    "mobile" : 100,
    "created_at" : ISODate("2020-01-06T03:40:09.560Z"),
    "updated_at" : ISODate("2020-01-06T03:42:51.022Z"),
    "__v" : 0
}

Seven, the use of plug-ins

1. Plug-in search address

2. Custom plug-ins

// 定义一个插件
const lastModified = (schema, option) => {
      
      
  schema.add({
      
       updated_at: Date });
  schema.pre('updateOne', (next) => {
      
      
    this.updated_at = moment(new Date()).format('YYYY-MM-DD HH:mm:ss');
    next();
  })
}

// 使用插入
UserSchema.plugin(lastModified);