Find document with array that contains a specific value

Question

If I have this schema...

person = {
    name : String,
    favoriteFoods : Array
}

... where the favoriteFoods array is popula

Answer 1

In case you need to find documents which contain NULL elements inside an array of sub-documents, I've found this query which works pretty well:

db.collection.find({"keyWithArray":{$elemMatch:{"$in":[null], "$exists":true}}})

This query is taken from this post: MongoDb query array with null values

It was a great find and it works much better than my own initial and wrong version (which turned out to work fine only for arrays with one element):

.find({
    'MyArrayOfSubDocuments': { $not: { $size: 0 } },
    'MyArrayOfSubDocuments._id': { $exists: false }
})