Updating nested List in mongoDB Query working sometimes but with large data set it fails [duplicate] - mongodb

Question

This question already has answers here:
Updating a Nested Array with MongoDB
(2 answers)
Closed 5 years ago.
Following is a MongoDB document:
{
"_id" : 2,
"mem_id" : M002,
"email" : "xyz#gmail.com",
"event_type" : [
{
"name" : "MT",
"count" : 1,
"language" : [
{
"name" : "English",
"count" : 1,
"genre" : [
{
"name" : "Action",
"count" : 6
},
{
"name" : "Sci-Fi",
"count" : 3
}
],
"cast" : [
{
"name" : "Sam Wortington",
"count" : 2
},
{
"name" : "Bruce Willis",
"count" : 4
},
{
"name" : "Will Smith",
"count" : 7
},
{
"name" : "Irfan Khan",
"count" : 1
}
]
}
]
}
]
}
I'm not able to update fields that is of type array, specially event_type, language, genre and cast because of nesting. Basically, I wanted to update all the four mentioned fields along with count field for each and subdocuments. The update statement should insert a value to the tree if the value is new else should increment the count for that value.
What can be the query in mongo shell?
Thanks

Answer 1

You are directly hitting one of the current limitations of MongoDB.
The problem is that the engine does not support several positional operators.
See this Multiple use of the positional `$` operator to update nested arrays
There is an open ticket for this: https://jira.mongodb.org/browse/SERVER-831 (mentioned also there)
You can also read this one on how to change your data model: Updating nested arrays in mongodb
If it is feasible for you, you can do:
db.collection.update({_id:2,"event_type.name":'MT' ,"event_type.language.name":'English'},{$set:{"event_type.0.language.$.count":<number>}})
db.collection.update({_id:2,"event_type.name":'MT' ,"event_type.language.name":'English'},{$set:{"event_type.$.language.0.count":<number>}})
But you cannot do:
db.collection.update({_id:2,"event_type.name":'MT' ,"event_type.language.name":'English'},{$set:{"event_type.$.language.$.count":<number>}})

Answer 2

Let's take case by case:
To update the field name in event_type array:
db.testnested.update({"event_type.name" : "MT"}, {$set : {"event_type.name" : "GMT"}})
This command will update the name for an object inside the event_type list, to GMT from MT:
BEFORE:
db.testnested.find({}, {"event_type.name" : 1})
{ "_id" : 2, "event_type" : [ { "name" : "MT" } ] }
AFTER:
db.testnested.find({}, {"event_type.name" : 1})
{ "_id" : 2, "event_type" : [ { "name" : "GMT" } ] }
2.To update fields inside event_type, such as language, genre that are intern list:
There is no direct query for this. You need to read the document, update that document using the JavaScript or language of your choice, and then save() the same. I dont think there is any other way available till mongo 2.4
For further documentation, you can refer to save().
Thanks!