Lookup in Mongodb aggregation

In MongoDB aggregation, the lookup stage is crucial for performing left joins between collections, much like SQL joins. This operator facilitates combining documents from different collections by matching fields. For example, in a scenario involving books and authors, you might use lookup to merge book documents with author details based on a common author ID. The lookup operation requires specifying the from collection, the localField (the field in the current collection), the foreignField (the matching field in the other collection), and the as field to store the results. After executing lookup, the resulting documents contain an array of matched documents. To simplify access to these details, the $addFields operator can be used to extract specific values. For instance, using arrayElement or first, you can streamline the data by selecting the first element from the array, thereby improving readability and usability of the results. This process helps integrate and query data efficiently in MongoDB aggregation pipelines, providing a powerful tool for complex data manipulations.

Welcome to a youtube channel dedicated to programming and coding related tutorials. We talk about tech, write code, discuss about cloud and devops. That’s what we do all day, all year. We roll out a lot of series and videos on our channel.

All the learning resources such as code files, documentations, articles and community discussions are available on our website:

You can find our discord link, github link etc on the above website.

[ragsbigfella]

Thanks for a wonder mini series!! appreciate it.

[AKSHATGANDHI-dipq]

I have completed both the series MongoDB basic to Advanced and Aggregation.
I don't think I have learned anything this much faster and with understanding of scenarios.
Thank You Sir 👍🏻🙇🏻‍♂.

[chandnijha]

Hey Sir, I have completed entire MERN with advanced MongoDB aggregation tutorial from your channels Chai aur code and this one. You have made the world of web development lot more simpler. When I would recall best teachers of my life, your name would surely be at top. In a world where people donot help or even help for some selfish reasons, you are working selflessly for us. I feel your spirit needs to be cherished more than your videos in youths globally. Tons of love and 🖖🙇🙇🙇🙇🙇🙇

[MegaVladikslavman]

The best explanation of aggregations in Mongo I've seen on Youtube. Thank you a lot for your work!

[amCoder]

and here i completed this series in a single day coz it was short upto point and most importantly the teaching of yours was really fun,
Thanks a lot for that sir!

[NHvines]

I work at a startup and my company uses mongodb queries extensively coupled with springboot. This series helped me a lot to understand mongodb aggregation pipeline in depth. Great Job Hitesh 👏👏👏

[prabhatdeshmukh]

Never seen a tutorial this comprehensive yet concise and understandable on an advanced topic like MongoDB aggregation, kudos to your effort and thanks a lot!

[ajaydeepsinghrajpoot]

Chai aur backend makes perfect sense after watching this series. Thankyou sir. I am building my Sass and if i'm able to make it work, the first payout will go to your channel.

[navneetverma]

This was a short set of video series but very easy to understand and able to relate it with some other similar scenarios.

Thanks for the wonderful series 🎉👏🏻👏🏻👏🏻

[annsabbasi]

Thanks It was such an interesting series and skyrocket my skills in MongoDB.
Since it was a little bit complicated but when I watched for the second time now everything is

[heeru]

I know you have other things to do but whenever you will have some time, please do upload videos in this playlist. We are very grateful to you that you bring this amazing series to us. Thank you.

[ridamsinghal]

Sir, best video for understanding the working of the $lookup operator in MongoDB. And at the same time the best series to understand MongoDB Aggregation Pipeline.

[techzone-lk-zone]

worked through each video . now its all clear, thanks mate

[Devlopsofar]

I really enjoyed the tutorial from start to the end I love the way you make your videos and the way you make the video so interactive and allow us to think for a solutions by our selves. I want to solve a problem with my aggregation but I wasn’t able to do so

[ravindupathum-ch]

i watched all the videos in this playlist. it is best

[piyushmishra]

finally completed !! Thanks a lot sir best content on Youtube..

[ayushpatel]

Thank u so much sir for this series. I just need to refresh my concepts and your videos r best

[tuhinghosh]

Thank you for this valuable series sir
Just completed now ❤
Happy teachers day ❤

[shankarraj]

I think we can use Unwind also, it also provides the same result " [
{
$lookup: {
from: "authors",
localField: "author_id",
foreignField: "_id",
as: "author_details"
}
},
{
$unwind: "$author_details"
}
]" response:"{
"_id": 1,
"title": "The Great Gatsby",
"author_id": 100,
"genre": "Classic",
"author_details": {
"_id": 100,
"name": "F. Scott Fitzgerald",
"birth_year": 1896
}
}",

[prateek]

Very helpful for me i am and frontend developer learning backend from somedays onto a live project getting insights from this aggregation pipeline is clear upto the point that i can work with it Thank you for such a beautiful series i loved it❤