Query MongoDB with length criteria

Question

I have several documents in a MongoDB Collection, with a field \'name\' (which is a String).

How can I perform queries like 7 <= name.length <= 14

Answer 1

Mongo provides a few ways to perform a query with length criteria – $where or $regex are two great options however I would recommend using $regex due to better query performance.

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$where (slower)

Accepts either a JavaScript expression or function in queries

Example:

db.collection.find({ $where: 'this.name.length >= 7 && this.name.length <= 14' })

Note: The $where operator will not take advantage of your database indexes, resulting in a much slower query. - Source

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$regex (faster)

Provides regular expression capabilities for pattern matching strings in queries

Example:

db.collection.find({ name: { $regex: /^.{7,14}$/ } })

Note: The $regex operator will take advantage of your database indexes, resulting in a much faster query (if your collection is indexed properly). - Source