Gain insights into MongoDB's core concepts, including queries, CRUD operations, aggregation, and more. Discover how to build applications with hands-on experience and interactive widgets.

mongo.tar.gz

MongoDB is an open-source NoSQL database and stores data in the form of documents. It can be used as an alternative to traditional relational databases. NoSQL databases are schema-less and useful for working with large sets of distributed data. 

In this course, you will learn the core concepts of MongoDB including queries, documents, embedded documents, and operators with advanced features like CRUD operations, bulk write operations, GridFS, indexing, aggregation pipeline, authorization, and more.

You will have plenty of hands-on experience with the help of interactive widgets, and by the end you will have a strong understanding of how to build MongoDB-based applications.

MongoDB: The Complete Guide

# Projection

The second argument to the `find` and `findOne` functions is a projection. It is a way to control what data the filter query returns.

## Return specific fields

First, let’s insert some documents.


db.tasks.insertMany([
{
  name: 'Task 1',
  priority: 1
},
{
  name: 'Task 2',
  priority: 2
}
]);

Next, we build a query to find documents and limit fields.

```
db.tasks.find({}, {name: 1});
```

This query returns the below output.

```
[
    { 
        _id: ObjectId("60fbf595b7b1ef7b709ecf28"), 
        name: 'Task 1' 
    },
    { 
        _id: ObjectId("60fbf595b7b1ef7b709ecf29"), 
        name: 'Task 2' 
    }
]
```
This returns only the `name` and  `_id` fields. 

## Return specific fields from embedded documents

First, let’s insert some embedded documents to use in our example. 


Learn and practice projection while reading MongoDB documents.

Introduction to Database and MongoDB

Create Database and Authorization

Performing CRUD Operations on MongoDB - Part 1

Performing CRUD Operations on MongoDB - Part 2

MongoDB Query and Database Performance

Learn Additional MongoDB Topics

Appendix

Read Documents: Part 7

Projection

Return specific fields