How to update a nested array value in mongodb? - json

Question

I want update a array value that is nested within an array value: i.e. set
status = enabled
where alerts.id = 2
{
"_id" : ObjectId("5496a8ed49847b6cd7c7b350"),
"name" : "joe",
"locations" : [
{
"name": "my location",
"alerts" : [
{
"id" : 1,
"status" : null
},
{
"id" : 2,
"status" : null
}
]
}
]
}
I would have used the position $ character, but cannot use it twice in a statement - multi positional operators are not supported yet: https://jira.mongodb.org/browse/SERVER-831
How do I issue a statement to only update the status field of an alert matching an id of 2?
UPDATE
If I change the schema as follows:
{
"_id" : ObjectId("5496ab2149847b6cd7c7b352"),
"name" : "joe",
"locations" : {
"my location" : {
"alerts" : [
{
"id" : 1,
"status" : "enabled"
},
{
"id" : 2,
"status" : "enabled"
}
]
},
"my other location" : {
"alerts" : [
{
"id" : 3,
"status" : null
},
{
"id" : 4,
"status" : null
}
]
}
}
}
I can then use:
update({"locations.my location.alerts.id":1},{$set: {"locations.my location.alerts.$.status": "enabled"}});
Problem is I cannot create indexes on the alert id :-(

Answer 1

it may be better of modelled as such, specially if an index on location and,or alerts.id is needed.
{
"_id" : ObjectId("5496a8ed49847b6cd7c7b350"),
"name" : "joe",
"location" : "myLocation",
"alerts" : [{
"id" : 1,
"status" : null
},
{
"id" : 2,
"status" : null
}
]
}
{
"_id" : ObjectId("5496a8ed49847b6cd7c7b350"),
"name" : "joe",
"location" : "otherLocation",
"alerts" : [{
"id" : 1,
"status" : null
},
{
"id" : 2,
"status" : null
}
]
}

Answer 2

I think you are having a wrong tool for the job. What you have in your example is relational data and it's much easier to handle with relational database. So I would suggest to use SQL-database instead of mongo.
But if you really want to do it with mongo, then I guess the only option is to fetch the document and modify it and put it back.