Django Aggregation & Annotation / values() and values_list() functions

In this video, we look at aggregation and annotation in Django - how to summarize and aggregate data to get summary statistics and insights into your application data.

We look at how to annotate models with additional data, using the annotate() function, and how to pair this with the values() function to create specific groupings of data that can then be analysed and aggregated.

We also look at the values() and values_list() functions in general in this video.

📌 𝗖𝗵𝗮𝗽𝘁𝗲𝗿𝘀:
00:00 Intro
01:37 values function on Django QuerySets
06:41 Transforming values with database functions
08:25 Getting Foreign Key data with values() function
10:47 values_list() function on Django QuerySets
13:48 Aggregating values in Django with aggregate() method
24:18 Annotating models in Django with annotate() method

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#python #django #webdevelopment #database #sql

[rhysjesett]

These are genuinely some of the most helpful tutorials on the Internet.

No fluff, just constant gold.

[gigi-hp]

Never seen a tutorial so well explained...❤

[XzibiTP]

I have watched so many tutorials and yours is the best i have come across. Its detailed easy to understand and structured. Keep the good work up. Thanks

[hemrajkaliraman]

Best series on Django advance topics. I have improved the performance of my project a lot. you are doing a great job creating a lot of value.

[khunjohn]

As usual, great tutorial. I hope that in the next video you include OuterRef and Subquery. This is a more advanced topic, but it packs a ton of functionality. ie. Let's say you have a company with many offices and one of those offices is market as the HQ. With OuterRef and Subquery, you can annotate the company address from the specific office in the many to one related table marked as the HQ and also aggregate the total amount of employees as a Sum of each office.

[codedjango]

Very nice explanation on aggregate and you so much

[seydinaoumarsamabaly]

I just want to thank you Master 🙌🏾before I finish watching the tutorial !

[robhafemeister]

Great video! you explained in less than an hour what probably took me a week to learn on my own awhile back. Love it!

[Rinpower]

very helpful, that's exactly what I was looking for, thanks again bro !!

[farzadmf]

SUPER high quality video as always; great job!

[repotranstech]

Thanks 👍 for this tutorial.I have a microfinance project that will require this.

[DhavalAhir]

Amazing every concept clear.
Love from India bro. ✌️

[priyanshvatsal]

So much useful information in just one video. Thanks

[ShivaR-kb]

awesome content Mate!! I learned many new concepts in this video and will try to apply in my projects too 😁

[paulwanjohi]

Incredible. That was so helpful. Thank you man👊

[anatoliyloboda]

It's a very interesting and important part of working with DB. Thank you for sharing!!!

[Septumsempra]

Great tutorial.
Any caching vids coming?

[firstandlast]

A little recap:
Annotate by itself (without values()) doesn't do grouping even with use of aggregate functions (which just duplicate argumented field in such case);
We use annotate() with values() and we don't use it with only() (at least my tests proved last as useless);
We can start from both child and parent Model and get the same result
So this:
Books.objects.values_list("author__firstname", "author__lastname").annotate(
total=Count("id")
)
And that:
q = Author.objects.values_list("firstname", "lastname").annotate(
total=Count("books")
)
will do the same (p.s. "books" in the last statement refers to "related_query_name" specified in ForeignKey field of the "Books" model );

[abbasebadian]

In the Concat topic, what if a field's value were empty? Is there a way to pass a fallback value for it ?

[azhariqbal]

Is there any package you use for runscript this is very useful for testing queries