如何在Go中正确使用MongoDB会话？

Question

I'm using MongoDB (gopkg.in/mgo.v2 package) as a database in my go app. According to MongoDB best practices I should to open connection when application starting and close it when application is terminating. To verify that connection will be closed I can use defer construction:

session, err := mgo.Dial(mongodbURL)
if err != nil {
    panic(err)
}
defer session.Close()

All will be good if I execute this code in main function. But I want to have this code in separate go file. If I do this session will be closed after method will be executed.What is the best way to open and close session in Golang according MongoDB best practices?

Answer 1

You can do something like this. Create a package which does the Db initialization

    package common

    import "gopkg.in/mgo.v2"

    var mgoSession   *mgo.Session

    // Creates a new session if mgoSession is nil i.e there is no active mongo session. 
   //If there is an active mongo session it will return a Clone
    func GetMongoSession() *mgo.Session {
        if mgoSession == nil {
            var err error
            mgoSession, err = mgo.Dial(mongo_conn_str)
            if err != nil {
                log.Fatal("Failed to start the Mongo session")
            }
        }
        return mgoSession.Clone()
    }

Clone reuses the same socket as the original session.

Now in other packages you can call this method:

package main

session := common.GetMongoSession()
defer session.Close()