compare multiple value in same document in mongodb

Question

My question was, how to find all title of the releases contains the artist name Here is the 2 Documents for just an example:

`{"release" : {"title" : "DEF day",
            "artists" : {"artist" : {"role" : "1","name" : "DEF"}}}
    }

{   "release" : {"title" : "XYZ day",
             "artists" : {"artist" : {"role" : "1","name" : "KYC"}}}
    }`

when i run this following query:

`db.test.find({$where:
  "this.release.title.indexOf(this.release.artists.artist.name) > -1"

})`

I get the result "DEF day", so it works excellent!! BUT, once i run this query to my original data(same format like above) i get this:

`error: {
"$err" : "TypeError: Object 30 has no method 'indexOf'\n    at _funcs1 (_funcs1:1:49) near 'his.release.artists.a' ",
"code" : 16722

}`

My collection is big (8GB+). Just looking at the above error, can anyone tell what may be the problem with the above query? your answer is appreciated. please.

Answer 1

The problem is in the data itself. Somewhere you have a document, where the title field is not String, thus invoking indexOf on the whole data, on that particular document you get the error.

One thing you can do to solve this problem is first of all find that erroneous document. To do that you will need to run a simple query.

MongoDB has the $type operator, which matches fields by their type. And here is the list of all available BSON types a MongoDB document field can have.

The id of String BSON type is 2, thus you need all the documents that have type of title field not equal to 2.

find({field: {$not: {$type: <BSON type>}}}))

After finding the document(s), you may fix or remove them.