in mongoDB i want to update an object depending upon object's other elements value - mongodb

Question

I have a collection in MongoDB.
{
"_id" : ObjectId("5aaf51369d8bdfe288d1cb71"),
"companyName" : "ABC",
"name" : "BCD",
"buildInfo" : [
{
"Branch" : "IT",
"Subjects" : [
"Math",
"English",
"Computer",
]
}
],
"currentDate" : ISODate("2018-03-14T14:09:24.374Z"),
"lastModifiedBy" : "ABC.com"
}
I want to insert a new object into "buildInfo" if that branch won't be there. If the branch exists I want to update "Subjects".
I am passing Branch and Subjects to this method.
myDb.collection('ABCDEF').findAndModify(
{'name':'BCD', 'companyName': 'ABC'},
[['_id','asc']],
{
$addToSet: {
'buildInfo.$[i].Subjects': Subjects
}
},
{ upsert: true, arrayFilters: [{ 'i.Branch': Branch }] }
But it's updating if the branch is there, but it's not creating a new object if a branch is not there.

Answer 1

Upsert works on document level only, not for embedded documents.
The simplest way is to issue 3 consecutive updates:
myDb.collection('ABCDEF').findAndModify(
{'name':'BCD', 'companyName': 'ABC', '$or': [{'buildInfo':{'$exists': false}}, {'buildInfo': {'$not':{ '$type': 'array' }}}]},
[['_id','asc']],
{
$set: { 'buildInfo': [] }
},
{ upsert: true}
)
followed by
myDb.collection('ABCDEF').findAndModify(
{'name':'BCD', 'companyName': 'ABC', 'buildInfo.Branch': {$nin: [Branch]}},
[['_id','asc']],
{
$push: {
{ buildInfo: { Branch: Branch, Subjects: [] } }
}
}
)
followed by
myDb.collection('ABCDEF').findAndModify(
{'name':'BCD', 'companyName': 'ABC', 'buildInfo.Branch': Branch},
[['_id','asc']],
{
$addToSet: {
'buildInfo.$[].Subjects': Subject
}
}
)
The first one adds empty buildInfo array to documents that does not have one. The second update adds a subdocument with specific Branch and empty Subjects to documents that don't have the branch. The last query adds Subject to the set.