使用gin Golang框架配置mongo

I'm trying to configure mongo in my Go app. I'm using the Gin framework. I'm also using the mgo V2 driver for mongo. I want to connect to mongo as a middlware. Here's what I got:

func Run(cfg common.Config) error {

doWorkResource := &DoWorkResource{db: dbmap}

r := gin.New()

r.Use(middleware.DB())


r.POST("/register", doWorkResource.Register)
r.POST("/login", doWorkResource.Login)

r.Run(cfg.SvcHost)

return nil
}

This is the DB function:

func DB() gin.HandlerFunc {
   session, err := mgo.Dial("localhost:27017")
   if err != nil {
       panic(err)
   }

   defer session.Close()

   return func(c *gin.Context) {
        s := session.Clone()

        db := s.DB("testing").C("testData")
        err = db.Insert(&Person{"Ale", "+55 53 8116 9639"},
            &Person{"Cla", "+55 53 8402 8510"})
        if err != nil {
            log.Fatal(err)
        }

        c.Next()
   }
}

type Person struct {
  Name  string
  Phone string
}

The insertion is executed if I run it directly from the main function, but not if it's run from the DB() function. In fact, I logged from within the return statement in the DB() function and nothing in there is being executed. I have a feeling I need to call it as an argument to one of my endpoints, but when I do that I get

cannot use middleware.DB (type func() gin.HandlerFunc) as type gin.HandlerFunc in argument to r.RouterGroup.POST