Skip to content
Studio 3T - The professional GUI, IDE and client for MongoDB
  • Tools
    • Aggregation Editor
    • IntelliShell
    • Visual Query Builder
    • Export Wizard
    • Import Wizard
    • Query Code
    • SQL Query
    • Connect
    • Schema Explorer
    • Compare
    • SQL ⇔ MongoDB Migration
    • Data Masking
    • Task Scheduler
    • Reschema
    • More Tools and Features
  • Solutions
  • Resources
    • Knowledge Base
    • MongoDB Tutorials & Courses
    • Tool/Feature Documentation
    • Reports
    • Case Studies
    • Whitepapers
    • Blog
    • Testimonials
    • Community
  • Contact us
    • Contact
    • Sales Support
    • Feedback and Support
    • Career
    • About Us
  • Store
    • Buy Now
    • Preferred Resellers
    • Team Pricing
  • My License
  • Download
search

Academy 3T

  • MongoDB 101: Getting Started
  • MongoDB 201: Querying MongoDB Data
  • MongoDB 301: Aggregation

Lesson 3, Exercise 4: Changing the field order in the aggregation pipeline

MongoDB 201: Querying MongoDB Data Working with the MongoDB Aggregation Pipeline Lesson 3, Exercise 4: Changing the field order in the aggregation pipeline

In this exercise, you will add the fourth stage to the pipeline. The stage is based on the $replaceRoot aggregate operator, which replaces input documents with output documents.

In this way, you can reorder the fields as they appear in the pipeline.

To change the field order in the aggregation pipeline

1. On the Pipeline tab of the Aggregation Editor, ensure that the Stage 3 row is selected (the $project row), click the small down arrow to the right of the Add button, and click Add New Stage After Selected Stage. 

The Aggregation Editor adds the Stage 4 tab to the right of the Stage 3 tab and makes the new tab active.

2. On the Stage 4 tab, select the $replaceRoot option from the Filter drop-down.

The $replaceRoot operator lets you change the order of the fields in the pipeline.

When you select the $replaceRoot option, the Aggregation Editor adds an expression that starts with the newRoot operator, followed by a placeholder.

You must precede your expression with the newRoot operator, along with a trailing colon. The expression itself should be enclosed in curly braces.

3. In the editor window, delete the placeholder and type the following expression after the newRoot operator and its trailing colon:

{city: "$city", total: "$total"}

The new code includes two elements, one for the city field and one for the total field.

The value assigned to each field is the original field, with the name preceded by the dollar sign. This ensures that the city field appears first, followed by the total field.

The complete expression should now look like the following code:

{
  newRoot: {city: "$city", total: "$total"}
}

4. In the Stage Output pane in the bottom section, click the Execute button. This will execute the pipeline up to and including the fourth stage.

The following figure shows part of the results, with the city field listed first, followed by the total field.

Execute output

5. Go to the Query Code tab. Verify that the code includes the $replaceRoot operator and its expression.

6. Go to the Pipeline tab. Verify that the pipeline includes the Stage 4 row and that the row contains the $replaceRoot operator and its expression.

Leave the Aggregation tab and aggregate statement in place for the next exercise.

Next – Lesson 3, Exercise 5: Sorting the documents in the aggregation pipeline
Previous Topic
Back to Lesson
Next Topic
  • Course Home Expand All
    Performing MongoDB CRUD Operations
    4 Topics | 1 Quiz
    Lesson 1, Exercise 1: Adding a document to a collection
    Lesson 1, Exercise 2: Viewing a document in a collection
    Lesson 1, Exercise 3: Updating a document in a collection
    Lesson 1, Exercise 4: Deleting a document from a collection
    Test your skills: Performing CRUD Operations
    Building MongoDB find() Queries
    4 Topics | 1 Quiz
    Lesson 2: The MongoDB find method
    Lesson 2, Exercise 1: Using IntelliShell to build and run find statements
    Lesson 2, Exercise 2: Using Visual Query Builder to build and run find statements
    Lesson 2, Exercise 3: Using Query Code and IntelliShell to modify and run a find statement
    Test your skills: Building MongoDB find() Queries
    Working with the MongoDB Aggregation Pipeline
    6 Topics | 1 Quiz
    Lesson 3: Introducing the MongoDB aggregate method
    Lesson 3, Exercise 1: Filtering the documents in the aggregation pipeline
    Lesson 3, Exercise 2: Grouping the documents in the aggregation pipeline
    Lesson 3, Exercise 3: Adding and removing fields in the aggregation pipeline
    Lesson 3, Exercise 4: Changing the field order in the aggregation pipeline
    Lesson 3, Exercise 5: Sorting the documents in the aggregation pipeline
    Test your skills: Working with the MongoDB Aggregation Pipeline
    Querying Arrays Using MongoDB $elemMatch
    3 Topics | 1 Quiz
    Lesson 4, Exercise 1: Using IntelliShell to query single and multiple values in an array
    Lesson 4, Exercise 2: Using Visual Query Builder to query a single array value
    Lesson 4, Exercise 3: Using Visual Query Builder to query multiple array values
    Test your skills: Querying Arrays Using MongoDB $elemMatch
    Querying Embedded Documents in MongoDB Arrays
    3 Topics | 1 Quiz
    Lesson 5, Exercise 1: Using the $elemMatch operator to query embedded documents
    Lesson 5, Exercise 2: Using conditional operators to query embedded documents
    Lesson 5, Exercise 3: Using Visual Query Builder to query embedded documents
    Test your skills: Querying Embedded Documents in Arrays
    Querying MongoDB with SQL SELECT Statements
    2 Topics | 1 Quiz
    Lesson 6, Exercise 1: Using the SQL Query tool to run SQL statements
    Lesson 6, Exercise 2: Using the SQL Query tool to aggregate collection data
    Test your skills: Querying MongoDB with SQL
    Working with MongoDB Views
    3 Topics | 1 Quiz
    Lesson 7, Exercise 1: Creating a MongoDB view
    Lesson 7, Exercise 2: Querying a MongoDB view
    Lesson 7, Exercise 3: Modifying and deleting a MongoDB view
    Test your skills: Working with MongoDB Views
    Course Extras
    Return to MongoDB 201: Querying MongoDB Data
  • Studio 3T

    MongoDB Enterprise Certified Technology PartnerSince 2014, 3T has been helping thousands of MongoDB developers and administrators with their everyday jobs by providing the finest MongoDB tools on the market. We guarantee the best compatibility with current and legacy releases of MongoDB, continue to deliver new features with every new software release, and provide high quality support.

    Find us on FacebookFind us on TwitterFind us on YouTubeFind us on LinkedIn

    Education

    • Free MongoDB Tutorials
    • Connect to MongoDB
    • Connect to MongoDB Atlas
    • Import Data to MongoDB
    • Export MongoDB Data
    • Build Aggregation Queries
    • Query MongoDB with SQL
    • Migrate from SQL to MongoDB

    Resources

    • Feedback and Support
    • Sales Support
    • Knowledge Base
    • FAQ
    • Reports
    • Case Studies
    • White Papers
    • Testimonials
    • Discounts

    Company

    • About Us
    • Blog
    • Careers
    • Legal
    • Press
    • Privacy Policy
    • EULA

    © 2022 3T Software Labs GmbH. All rights reserved.

    • Privacy Policy
    • Cookie settings
    • Impressum
    When you click "Accept", you are agreeing to cookies being on your device. They may improve site navigation, site usage analysis, or the relevance of messages. It is up to you which cookies are enabled. Read our Privacy Policy.
    Manage cookies
    Accept
    ✕

    Privacy Preference Center

    A cookie is a small file of letters and numbers that is downloaded on to your computer when you visit a website. Cookies are used by many websites and can do a number of things, eg remembering your preferences, recording what you have put in your shopping basket, and counting the number of people looking at a website. In the form below you can choose which cookies, except for essential cookies, to allow or disable.

    Accept all cookies

    Manage consent preferences

    Essential cookies are strictly necessary to provide an online service such as our website or a service on our website which you have requested. The website or service will not work without them.

    Performance cookies allow us to collect information such as number of visits and sources of traffic. This information is used in aggregate form to help us understand how our websites are being used, allowing us to improve both our website’s performance and your experience.

    Functional cookies collect information about your preferences and choices and make using the website a lot easier and more relevant. Without these cookies, some of the site functionality may not work as intended.

    Social media cookies are cookies used to share user behaviour information with a third-party social media platform. They may consequently effect how social media sites present you with information in the future.

    Accept selected