Insert a slice result JSON into MongoDB - json

Question

I'm using the mgo driver for MongoDB, with the Gin framework.
type Users struct {
User_id *string `json:"id user" bson:"id user"`
Images []string `json:"images" bson:"images"`
}
I have this function which tries to convert the slice into JSON.
The slice here is UsersTotal
func GetUsersApi(c *gin.Context) {
UsersTotal, err := GetUsers()
if err != nil {
fmt.Println("error:", err)
}
c.JSON(http.StatusOK, gin.H{
"Count Users": len(UsersTotal),
"Users Found ": UsersTotal,
})
session, err := mgo.Dial(URL)
if err == nil {
fmt.Println("Connection to mongodb established ok!!")
cc := session.DB("UsersDB").C("results")
err22 := cc.Insert(&UsersTotal)
if err22 != nil {
fmt.Println("error insertion ", err22)
}
}
session.Close()
}
Running it I get the following error:
error insertion Wrong type for documents[0]. Expected a object, got a array.

Answer 1

Inserting multiple documents is the same as inserting a single one because the Collection.Insert() method has a variadic parameter:
func (c *Collection) Insert(docs ...interface{}) error
One thing you should note is that it expects interface{} values. Value of any type qualifies "to be" an interface{}. Another thing you should note is that only the slice type []interface{} qualifies to be []interface{}, a user slice []User does not. For details, see Type converting slices of interfaces in go
So simply create a copy of your users slice where the copy has a type of []interface{}, and that you can directly pass to Collection.Insert():
docs := make([]interface{}, len(UsersTotal))
for i, u := range UsersTotal {
docs[i] = u
}
err := cc.Insert(docs...)
// Handle error
Also please do not connect to MongodB in your handler. Do it once, on app startup, store the global connection / session, and clone / copy it when needed. For details see mgo - query performance seems consistently slow (500-650ms); and too many open files in mgo go server.