<Mongodb query returns null for nested queries (KM...

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Mongodb query returns null for nested queries (KMongo)
I'm new to ktor and am writing an application using it. I'm trying to add authors and their book titles and retrieve them from the database. My schema is given below.
(authors is my collection name)
authors = [
{

name: "Author1",
books: [

{title:"Book1"},
{title:"Book2"}

]
}
]

I'm trying to check whether a book title has already been added under a particular author. So I wrote a findBookitemBytitle function as shown below. My issue is that every time I'm getting a null result. Even...