Find a value in multiple nested fields with the same name in MongoDB - mongodb

Question

In some documents I have a property with a complex structure like:
{
content: {
foo: {
id: 1,
name: 'First',
active: true
},
bar: {
id: 2,
name: 'Second',
active: false
},
baz: {
id: 3,
name: 'Third',
active: true
},
}
I'm trying to make a query that can find all documents with a given value in the field name across the different second level objects foo, bar, baz
I guess that a solution could be:
db.getCollection('mycollection').find({ $or: [
{'content.foo.name': 'First'},
{'content.bar.name': 'First'},
{'content.baz.name': 'First'}
]})
But a I want to do it dynamic, with no need to specify key names of nested fields, nether repeat the value to find in every line.
If some Regexp on field name were available , a solution could be:
db.getCollection('mycollection').find({'content.*.name': 'First'}) // Match
db.getCollection('mycollection').find({'content.*.name': 'Third'}) // Match
db.getCollection('mycollection').find({'content.*.name': 'Fourth'}) // Doesn't match
Is there any way to do it?

Answer 1

I would say this is a bad schema if you don't know your keys in advance. Personally I'd recommend to change this to an array structure.
Regardless what you can do is use the aggregation $objectToArray operator, then query that newly created object. Mind you this approach requires a collection scan each time you execute a query.
db.collection.aggregate([
{
$addFields: {
arr: {
"$objectToArray": "$content"
}
}
},
{
$match: {
"arr.v.name": "First"
}
},
{
$project: {
arr: 0
}
}
])
Mongo Playground
Another hacky approach you can take is potentially creating a wildcard text index and then you could execute a $text query to search for the name, obviously this comes with the text index/query limitations and might not be right for your usecase.