Koa封装Mongodb数据库

忘是亡心i 2022-11-30 05:48 188阅读 0赞

//DB库
    const {  MongoClient } = require('mongodb');
    
    const app = { 
        dbUrl: "mongodb://localhost:27017/",
        dbName: "book"
    }
    
    let client = new MongoClient(Config.dbUrl, {  useUnifiedTopology: true });
    
    class Db { 
    
        static getInstance() {    /*1、单例 多次实例化实例不共享的问题*/
    
            if (!Db.instance) { 
                Db.instance = new Db();
            }
            return Db.instance;
        }
    
        constructor() { 
    
            this.dbClient = ''; /*属性 放db对象*/
            this.connect();   /*实例化的时候就连接数据库*/
    
        }
    
        connect() {   /*连接数据库*/
            let _that = this;
            return new Promise((resolve, reject) => { 
                if (!_that.dbClient) {          /*1、解决数据库多次连接的问题*/
                    client.connect((error) => { 
                        if (error) { 
                            reject(error)
                            return;
                        }
                        console.log('数据库连接成功！！！');
                        _that.dbClient = client.db(Config.dbName);
                        resolve(_that.dbClient)
                    })
                } else { 
                    resolve(_that.dbClient);
                }
    
            })
    
        }
    
        find(collectionName, json) { 
    
            return new Promise((resolve, reject) => { 
    
                this.connect().then((db) => { 
    
                    var result = db.collection(collectionName).find(json);
    
                    result.toArray(function (err, docs) { 
    
                        if (err) { 
                            reject(err);
                            return;
                        }
                        resolve(docs);
                    })
    
                })
            })
        }
        update() { 
    
        }
        insert() { 
    
    
        }
    }
    //测试查询数据
    let myDB = new Db();
    myDB.find("users", { }).then((data) => { 
        console.log(data)
    })
    
    module.exports = Db.getInstance();