Increment a property value of an element in array object mongodb-node

Question

I am trying to increment a value of an element here's my array object

"options": [
 {
 "key": "banana",
 "votes": 0
 },
 {
 "key": "apple",
 "votes": 0
 },
 {
 "key": "mango",
 "votes": 0
 },
 {
 "key": "grapes",
 "votes": 0
 }
]

im trying to increment the votes value of the selected item while also matching the id of that data

 db().collection('polls').update( 
 { _id: id, "options.key": item },
 {$set: { $inc: { "options.$.votes" : 1 } }})

But it didn't work... the db() here is a function that returns the db.. im not getting any errors.

here is the full data

{
 "_id": {
 "$oid": "5aae26203ab1cc0f15e43dc6"
 },
 "author": "me",
 "title": "fruits you love the most",
 "options": [
 {
 "key": "banana",
 "votes": 0
 },
 {
 "key": "apple",
 "votes": 0
 },
 {
 "key": "mango",
 "votes": 0
 },
 {
 "key": "grapes",
 "votes": 0
 }
 ]
}

Answer 1

Remove $set and try. It should work then. Also, the db should be used without paranthesis like db and not db():

db.collection('polls').update( 
 { _id: id, "options.key": item },
 { $inc: { "options.$.votes" : 1 } }
)

If you are running this query directly in your mongodb shell then you need to specify _id: ObjectId(id) in your query so your query will be:

var id = '5aaf66812b0e3813178a8a14'
db.collection('polls').update( 
 { _id: ObjectId(id), "options.key": item },
 { $inc: { "options.$.votes" : 1 } }
)

• Ankit Agarwal: Are you running this script from mongoose or directly on mongodb?
• Ankit Agarwal: If its directly on mongodb then you should be using _id: ObjectId(id)

Answer 2

You are doing thing all correct but only one mistake is $inc should not be inside $set.

Following will fulfil your requirement.

 db.collection.update(
 {"options.key": "banana" },
 { $inc: { "options.$.votes" : 1 } }
 )

• JEEZSUSCRIZE: this works but i also want to match the data id so it just updates that particular data..
• krishnashu: then you can add data id field too in search filter. :)