Sorting according to time in string in mongodb - mongodb

Question

How can i sort if my time(time_required) is saved in this format ?
quiz_customer_record
{
"_id" : ObjectId("5f16eb4a5007bd5395c76ed9"),
"quiz_id" : "5f05bbd10cf3166085be68fc",
"user_id" : "5f06e0ddf718c04de30ea47f",
"name" : "ABC",
"time_required" : "0:6 Mins",
"questions_attempted" : 0,
"total_quiz_questions" : 1,
"attempt_date" : "2020-07-21T13:19:08.025Z"
},
{
"_id" : ObjectId("5f16eb5f5007bd5395c76edb"),
"quiz_id" : "5f05bbd10cf3166085be68fc",
"user_id" : "5f06e0ddf718c04de30ea47f",
"name" : "ABC",
"time_required" : "0:8 Mins",
"questions_attempted" : 0,
"total_quiz_questions" : 1,
"attempt_date" : "2020-07-21T13:19:29.377Z"
}
I want to sort it according to time_required but its in string and is in format of Mins:Seconds. Yes its a pretty messed up. But do we have a solution? I want to use mongo query for that as there are so many records and i sort of need to use limit(for pagination). That is why it is necessary for using mongo query.
Expected Result- Sort type- descending()
{
"_id" : ObjectId("5f16eb5f5007bd5395c76edb"),
"quiz_id" : "5f05bbd10cf3166085be68fc",
"user_id" : "5f06e0ddf718c04de30ea47f",
"name" : "ABC",
"time_required" : "0:8 Mins",
"questions_attempted" : 0,
"total_quiz_questions" : 1,
"attempt_date" : "2020-07-21T13:19:29.377Z"
},
{
"_id" : ObjectId("5f16eb4a5007bd5395c76ed9"),
"quiz_id" : "5f05bbd10cf3166085be68fc",
"user_id" : "5f06e0ddf718c04de30ea47f",
"name" : "ABC",
"time_required" : "0:6 Mins",
"questions_attempted" : 0,
"total_quiz_questions" : 1,
"attempt_date" : "2020-07-21T13:19:08.025Z"
}
The query i'm using is
db.quiz_customer_record.aggregate([{ $match: { quiz_id:quiz_id}},
{
$sort: { attempt_date: -1 }
},
{
$group: {
_id: "$user_id",
result1: { $first: "$attempt_date" },
quiz_id: { $first: "$quiz_id" },
time_required: { $first: "$time_required" },
o_id: { $first: "$_id" }
}
},
{
$project: {
_id: "$o_id",
user_id: "$_id",
quiz_id:"$quiz_id",
time_required:"$time_required",
result1: 1
}
}
]).sort({time_required:-1})

Answer 1

Answer for mongo version less than 4.2
$set was added in 4.2 version. For earlier version $addFields can be used.
db.collection.aggregate([
{
"$addFields": {
"time_required_split": {
$substr: [
"$time_required",
0,
3
]
}
}
},
{
"$addFields": {
"time_required_split": {
$split: [
"$time_required_split",
":"
]
}
}
},
{
"$addFields": {
"time_seconds": {
$sum: [
{
"$multiply": [
{
$toInt: {
$arrayElemAt: [
"$time_required_split",
0
]
}
},
60
]
},
{
$toInt: {
$arrayElemAt: [
"$time_required_split",
1
]
}
}
]
}
}
},
{
"$sort": {
time_seconds: -1
}
},
{
"$project": {
"time_required_split": 0,
"time_seconds": 0
}
}
])
Mongo Playground

Answer 2

Try this query -
db.collection.aggregate([
{
"$set": {
"time_required_split": {
$substr: [
"$time_required",
0,
3
]
}
}
},
{
"$set": {
"time_required_split": {
$split: [
"$time_required_split",
":"
]
}
}
},
{
"$set": {
"time_seconds": {
$sum: [
{
"$multiply": [
{
$toInt: {
$arrayElemAt: [
"$time_required_split",
0
]
}
},
60
]
},
{
$toInt: {
$arrayElemAt: [
"$time_required_split",
1
]
}
}
]
}
}
},
{
"$sort": {
time_seconds: -1
}
},
{
"$project": {
"time_required_split": 0,
"time_seconds": 0
}
}
])
Mongo Playground
Let me know if don't understand any stage.