mongoDB：检查文档中是否存在嵌套对象

Question

I need a find query, which is searching for an existing attribute in an array.

If this is the document...

document

{
    id: '123',
    attr: 'anything',
    author: [
        { id: '1' },
        { id: '2' }
    ]
}

... I want to check if there is a document with an author id existing:

find query

var id = '123';
var uid = '2';

Collection.find({ _id: id, author: { id: uid } })

This should give me one result.

If uid = '3' there would be no result.

Answer 1

Use "dot notation" to denote embedded fields:

Collection.find({ "_id": id, "author.id": uid })

Otherwise you are asking for a document that has "exactly" and only a single object with the requested value. This just asks "does one possible value match".