在express js的不同文件中访问db连接的同一个实例

我有4个文件：

1) db.js - mongodb connection 2) socket.js - for all socket events 3) route.js - route for / 4) app.js - main start point for express app 

我想从db.js in socket.js and route.js共享相同的数据库实例，以便连接到数据库只有一次。

我已经尝试了2种方法：

 1) require db.js in both files, but this creates new connection every time require is called. 2) pass the collections in request object in db.js, but then how would I access the request object in socket.js in io.on("connection",function(socket){ // request ?? }) 

如何解决？

Answer 1

你可以移动到dependency injection设置，而不是在每个文件中显式地要求db.js ，这将允许你重用你现有的db连接：

main.js

 // require and setup db like normal var db = require('./db.js'); // require route, but now call it as a function and pass your db instance var route = require('./route.js)(db); 

route.js

 module.exports = function(db, maybeOtherSharedResources) { // existing code from route.js }