MongoDB find, lt and gt Examples

find, lt and gt ExamplesUse the MongoDB find method with lt and gt queries to find ranges of documents.

This page was last reviewed on Oct 11, 2023.

Find, MongoDB. A real estate database might have a price for each house. We want to find just properties that have a field within a range of values (like a certain price).

With special range queries, used with the find() method, we can find documents with fields in a certain range. The $lt and $gt terms are useful here.

A program. Here we have a real estate database with 3 houses in it. Each house has a different price. We use find() to get matching houses with prices less than, or greater than, a value.

Note We use the string "$lt" in a nested dictionary argument to find a range of prices less than a value.

Note 2 The "$gt" operator works the same way as less than, but means greater than.

from pymongo import MongoClient client = MongoClient("mongodb://127.0.0.1:27017") db = client.real_estate # Reset. db.houses.delete_many({}) # Insert houses. db.houses.insert_many([ {"address": "100 Main St.", "price": 45000}, {"address": "110 Main St.", "price": 50000}, {"address": "1400 Rich Ave.", "price": 200000}, ]) # Find inexpensive houses. print("FIND PRICE LT 60000") cursor = db.houses.find({"price": {"$lt": 60000}}) for doc in cursor: print(doc) # Find expensive houses. print("FIND PRICE GT 60000") cursor = db.houses.find({"price": {"$gt": 60000}}) for doc in cursor: print(doc)

FIND PRICE LT 60000 {'address': '100 Main St.', '_id': ObjectId('59f122302514972194e7e975'), 'price': 45000} {'address': '110 Main St.', '_id': ObjectId('59f122302514972194e7e976'), 'price': 50000} FIND PRICE GT 60000 {'address': '1400 Rich Ave.', '_id': ObjectId('59f122302514972194e7e977'), 'price': 200000}

Notes, comparison operators. For small groups of documents, getting all documents and then checking them in an if-statement in Python is possible.

However For large amounts of data, this because impossible. Using MongoDB to query for ranges (with lt and gt) is faster.

A review. Find() can be used with ranges. A dictionary argument with a special term (lt or gt) enables a range query. For large databases, this is essential.

Dot Net Perls is a collection of tested code examples. Pages are continually updated to stay current, with code correctness a top priority.

Sam Allen is passionate about computer languages. In the past, his work has been recommended by Apple and Microsoft and he has studied computers at a selective university in the United States.

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