Use of mongodb and mongoose

* This paper is the third in this series, you can go directly to github want to see more projects: https://github.com/hellozhangran/happy-egg-server
more of the description can be seen: HTTPS: //www.cnblogs. com / zhangran / p / 11963616.html

mongodb

mongodb is a typical non-relational database, presentation about its background, strengths and weaknesses not go into details here, we speak directly to practical operation or most likely part used.

mongodb common commands

mongod --config /opt/mongodb/mongod.conf Start mongod service.
- If you want to start in the background, you need to modify mongod.conf, add fork = true, then start.
- Mongod want to turn off the service running in the background, first check all the services running in the background lsof -i, find the pid number mongod,kill yourpid
mongo Mongo into the environment
show dbs View all databases
use test Into the test database
db.createCollection('user')Create a usercollection
- Briefly outline the concept set, Mongo non-relational database, the concept does not exist in the table, and is set to correspond to the table. Of course, not a collection of tables, and the tables vary greatly, there is no table of ranks of the structure, you can simply put the collection as a list, and the list which will put one object. There are not found that like most of the json data format.
db.user.insert({name: 'zhangsan', age: 21, sex: 'male'}) Inserted in a data set
db.user.find() All data in the user view the collection
db.user.find().pretty() Display data in the format of a nice point
db.user.find({name: 'zhangsan'}) Find first parameter is the selection condition where the display data that meets the entire name = 'zhangsan' of
db.user.find({name: 'zhangsan'}, {name: 1}) The first parameter is specified find display to show qualified name, 1 is a 0 is not displayed.

Use mongoose

mongoose is a nodejs tool library, easy to use nodejs operation mongodb

1. First Use mongoose database connection mongodb

const mongoose = require('mongoose');

// 创建一个连接，并监听各种事件，在执行connect操作时，各事件会视具体情况而触发。
mongoose.connection
.on('error', function (err) {
    // 数据库连接失败时触发
    console.log('connect error: ', err);
})
.on('disconnected', function () {
    // 数据库断开时触发，断开重连的逻辑可以放在这里。
})
.once('open', function () {
    // 数据库连接成功时触发，express开启listen的逻辑可以放在这里。
});

// 启动mongod服务默认是运行在127.0.0.1上，所以下面路径是localhost
// test是数据库名，如果有则连接，如果无则创建
mongoose.connect('mongodb://localhost/test', {
    useNewUrlParser: true,
    useUnifiedTopology: true
});

2. Schema and Model

In the mongoose in Schema, Model is a very important concept. Model mongodb the corresponding set collection, and a set of corresponding structures Schema, which is the type field, fields are combined, if required, whether there is a default value and the like.

const UserSchema = mongoose.Schema({
    name: String,
    age: Number,
    sex: Boolean
});

// Schema的静态方法
UserSchema.statics.findUserByAge = function (age) {
    // 用then来拿到结果，如findUserByAge(21).then((res) => {})。
    // 也可以在find第二个参数传回调函数
    return this.find({'age': age});
}

// Schema的实例方法
UserSchema.methods.findUserByName = function(name) {
    return this.model('User').find({ name: name });
};

// 创建一个Model，第三参数指定mongodb中collection的名字，如果不传则默认为变为复数（即Users）
const User = mongoose.model('User', UserSchema, 'user');

// 创建一条数据
// 1. 直接用User创建
User.create({name: 'zhangsan', age: 27, sex: true}, function(err, info) {
    console.log(info);
});

// 2. 新创建一个对象再添加数据到数据库
// 再次说明下现在mongoose默认是支持promise方式的，可以使用then 或 回调函数的方式
var person = new User({name: 'lisi', age: 20, sex: false});
person.save().then(res => {
    console.log(res);
})

// 调用Schema中定义的静态方法，可以通过User直接调
User.findUserByAge(21);

// 调用Schema中定义的实例方法方法，先实例化再调
const user = new User();
user.findUserByName('zhangsan');

// 删除数据，删除符合条件的一条
User.deleteOne({name: 'lisi'}).then();

// 删除符合条件的所有数据
User.deleteMany({age: 20}).then();

// 注意：remove()方法已经被弃用了！

Finally, attach the mongoose api documentation, the use of other methods are not listed:

http://www.mongoosejs.net/docs/api.html

EVERYTHING

Mentioned above is the current project has been used, follow-up is likely to continue to expand:

docker and mongodb
mongodb automatically copied set of disaster recovery

[Re-learn Node.js mongodb first 3] and the use of mongoose