One of the key features of MongoDB is its ability to sort documents based on various criteria. In this blog post, we will explore how to sort documents in MongoDB and provide examples to demonstrate the sorting functionality.
Sorting Documents in MongoDB
MongoDB provides the sort() method to sort documents in a collection. This method takes one or more sorting criteria as input and returns a cu rsor pointing to the sorted documents. The sorting criteria can be specified using the sort() method in the following format:
db.collection.find().sort({ field1: 1, field2: -1 });
In the above example, collection represents the name of the collection where the documents are stored. The find() method is used to retrieve documents from the collection, and the sort() method is chained to it to specify the sorting criteria. In this case, the documents will be sorted in ascending order based on field1 and in descending order based on field2.
Sorting in Ascending Order
To sort documents in ascending order, you can specify the field to sort by with a value of 1. Let's consider an example where we have a collection named books with documents representing books and their corresponding publication years. To sort the books in ascending order based on their publication years, we can use the following query:
db.books.find().sort({ year: 1 });
This query will return a cursor pointing to the documents in the books collection, sorted in ascending order based on the year field.
Sorting in Descending Order
To sort documents in descending order, you can specify the field to sort by with a value of -1. Let's continue with our previous example and sort the books in descending order based on their publication years:
db.books.find().sort({ year: -1 });
This query will return a cursor pointing to the documents in the books collection, sorted in descending order based on the year field.
Sorting on Multiple Fields
MongoDB also allows sorting on multiple fields. When sorting on multiple fields, the sorting criteria are applied in the order they are specified. Let's consider the books collection again and assume that each document contains both a year field and a title field. To sort the books first by publication year in ascending order and then by title in descending order, we can use the following query:
db.books.find().sort({ year: 1, title: -1 });
This query will return a cursor pointing to the documents in the books collection, sorted first in ascending order based on the year field, and for documents with the same year, sorted in descending order based on the title field.