MongoDB and Python

Introduction to MongoDB Query Language

MongoDB queries are represented as a JSON-like structure, just like documents. To build a query, you specify a document with properties you wish the results to match. MongoDB treats each property as having an implicit boolean AND. It natively supports boolean OR queries, but you must use a special operator ($or) to achieve it. In addition to exact matches, MongoDB has operators for greater than, less than, etc.

Sample query document to match all documents in the users collection with firstname “jane”:

q  = {
    "firstname" : "jane"
}

If we wanted to retrieve all documents with firstname “jane” AND surname “doe”, we would write:

q = {
    "firstname" : "jane",
    "surname" : "doe"
}

If we wanted to retrieve all documents with a score value of greater than 0, we would write:

q = {
    "score" : { "$gt" : 0 }
}

Notice the use of the special “$gt” operator. The MongoDB query language provides a number of such operators, enabling you to build quite complex queries.

See the section on MongoDB Query Operators for details.