How to Search for an Object by its ObjectId in the Mongo Console?

In MongoDB, every document has a its unique ObjectId that acts as its primary key. ObjectId helps to search for an object using its ObjectId can be incredibly useful when managing and interacting with your MongoDB databases.

In this article, we will explore How to search for an object by its ObjectId in the Mongo console By the end of this guide, you will be confident in your ability to search for and retrieve objects using their ObjectIds in the MongoDB console.

How to Search for an Object by its ObjectId?

When working with MongoDB process of searching for an object by its ObjectId in the MongoDB console. ObjectId is a unique identifier for every document in a MongoDB collection and knowing how to search for an object using its ObjectId can have multiple approaches. Below are the approaches that help us How to Search for an Object by its ObjectId:

1. Using the find() method
   
2. Using the findOne() method

Let's set up an Environment:

To understand How to search for an object by its ObjectId we need a collection and some documents on which we will perform various queries. Here we will consider a collection called courses which contains information like course name, Instructor name, fees, and duration. of the courses in various documents.

1. Using the find() method

The find() method in MongoDB is used to retrieve documents from a collection. It is one of the most commonly used methods in MongoDB.

Syntax:

db.collection.find(query, projection)

• query: is an optional parameter that specifies the query filter.
• projection: is an optional parameter that specifies which fields to include in the returned documents.

Example 1: Get the Java Course Details

Query:

var objectId= ObjectId("6616b9f157bac1647326e11d")
db.courses.find({_id: objectId})

Output:

The above query creates a variable objectId and assigns it the value of a MongoDB ObjectId "6616b9f157bac1647326e11d", and then it uses the find() method to retrieve a document from the courses collection where the _id field matches the objectId value.

Example 2: Get the Python Course Details

Query:

var objectId= ObjectId("6616b9f157bac1647326e11e")
db.courses.find({_id: objectId})

Output:

The above query creates a variable objectId and assigns it the value of a MongoDB ObjectId "6616b9f157bac1647326e11e", and then it uses the find() method to retrieve a document from the courses collection where the _id field matches the objectId value.

2. Using the findOne() method

The findOne() method in MongoDB is used to retrieve a single document from a collection that matches the specified query. It returns the first document that matches the query filter or null if no documents match the filter.

Syntax:

db.collection.findOne(query, projection)

• query: is an optional parameter that specifies the query filter.
• projection: is an optional parameter that specifies which fields to include in the returned document.

Example 1: Get the Java Course Details

Query:

var objectId= ObjectId("6616b9f157bac1647326e11d")
db.courses.findOne({_id: objectId})

Output:

The above query creates a variable objectId with the value of a MongoDB ObjectId "6616b9f157bac1647326e11d", and then uses the findOne() method to retrieve the first document from the courses collection where the _id field matches the objectId value.

Example 2: Get the Python Course Details

Query:

var objectId= ObjectId("6616b9f157bac1647326e11e")
db.courses.findOne({_id: objectId})

Output:

The above query creates a variable objectId with the value of a MongoDB ObjectId "6616b9f157bac1647326e11e", and then uses the findOne() method to retrieve the first document from the courses collection where the _id field matches the objectId value.

Conclusion

Overall in summary , findOne() returns a single document, while find() returns a cursor object that can be used to iterate over multiple documents. The findOne() method is useful when you know that only one document matches the specified query, or when you only need to retrieve a single document. Suppose if there are multiple documents in the collection that match the query filter, the findOne() method returns only the first one. If you want to retrieve all the documents that match the filter, you should use the find() method instead.