问题
I have Author and Book models.
An Author has many embedded Books.
Can I query the embedded Books, or do I have to fetch Authors first to get Books?
回答1:
You can query embedded documents, just qualify the name. Now, this will return all Authors that have books that match your query.
If Author is defined as having many :books (and book is an embedded::document)
@authors_with_sewid = Author.where("books.name" => "sewid").all
You'd then need to iterate over the authors and extract the books.
来源：https://stackoverflow.com/questions/3954520/mongoid-mongodb-and-querying-embedded-documents