In the back end i m using go lang and for database i use mongoDB. I m trying to find the last document inserted in the embedded array so i can retrieve the document in the last array index without knowing its index.Right now i m getting all the documents of the employee and then find the last index.It is like overloading my RAM as i need to retrieve 1000 of record of employee and store it in ram before finding the last index of the array My struct is as follows
type (
Employee struct {
Name string
Password string
EmpId string
EmailAddress string
Position string
Gender string
Nationality string
Department string
MaritalStatus string
Approvedby string
JoinDate time.Time
ConfirmationDate time.Time
EndDate time.Time
Leave []*LeaveInfo
}
LeaveInfo struct {
Total float64
Id int
Days float64
From time.Time
To time.Time
Status string
Certificate []*CertificateInfo
}
CertificateInfo struct {
FileName string
FileType string
FileSize int
}
Here is how i do in my application
My code is follows
employee := Employee{}
err = c.Find(bson.M{
"empid": "1234"
}).One(&result)
if err != nil {
log.Fatal(err)
}
name:=result.Name
lastindex:= result.LeaveInfo[len(result.LeaveInfo)-1].Id
As you can see i retrive the whole employee data and then find the Id of the last document.Is there any better way to do this.Appreciate any help.Please ...Thanks..
Newly Added Codes
This code is based on your example
var result bson.M
query := bson.M{"empid": "1234"} // gets the employee you are interested in
match := bson.M{"$match": query} // Set up the match part of the pipeline
unwind := bson.M{"$unwind": "$leave"} // sets up the leave field to be unwound
pipeline := []bson.M{match, unwind,{
"$project":bson.M{
"ID":bson.M{
"$slice": []interface{}{"$leave.id", -1},
}
}
iter := postCollection.Pipe(pipeline).Iter()
for iter.Next(&result) {
fmt.Printf("%+v
", result)
}
iter.Close()
This code gives me lot of same document like 542 documents .But all these document are same...