Aggregates, Entities & Value Objects | Modeling Rules of Thumb + Modeling Steps

[@liordagan5098]

Thanks!

[@amantinband]

OMG thank you so much! I really really appreciate it, I want you to know that your donation means the word to me. I love you, and I'll see you at dinner 😘

[@amantinband]

Hey everyone! Just wanted to apologize in advance for the sound quality, had it misconfigured ☹. It should improve significantly next Monday 🤞

[@MilanJovanovicTech]

I was about to send you a PM, but you hear it 😁

[@PhantomAxxaxxin]

Was gonna say, lol. For having such a nice mic it sure sounds like a potato.

[@ChrisAthanas]

Yes this video deserves to be remade with improved audio bc the content is valuable

[@adamv5219]

Nice video. The way you listed the modelling steps and “questions to ask” are so helpful. ❤

[@silvertek]

I cant wait to get back into the code! The last few videos have been great to step back and look at processes from a higher level. I'm hungry for more BuberDinner.

[@amantinband]

Same here. Next week we are coming back to the code in full force 💪🏼

[@sushilb7994]

Couldn't agree more... Last few videos have set the stage to deep dive into DDD 💪

[@MilanJovanovicTech]

Excellent high level explanation of these concepts. When are you going to show us the code? 🔥

[@amantinband]

Next week 🤙🏼

[@MilanJovanovicTech]

@@amantinband Awesome, can't wait

[@amanamudoaka8020]

The saviour is here. I completely get it. But we need a video for a full usage of most of the concepts. Well done teacher.

[@amantinband]

No worries we’ll cover everything with practical examples

[@amantinband]

Curious to hear what you think! Do you have experience with modeling a domain? Do you have a different approach? Do you have different rules of thumb? Are you new to DDD? Do you have any questions regarding any of concepts?

[@danil3700]

Just today I was looking for information about aggregates, thanks! Can't wait next video

[@amantinband]

Awesome to hear. Are you modeling a domain or onboarding to an existing project?

[@danil3700]

@@amantinband I have a project at the university and I want to model it using DDD. I've looked at a lot of information about this, but your videos are awesome. Structured, useful information, and even with project examples

[@amantinband]

Oh cool! Next Monday’s video is going to be a practical example I think you’ll find useful as well

[@alexkovanev1425]

Great and simple explanation

[@amantinband]

Thanks Alex 🙏🏼

[@manuelknorle1457]

Once again an extremely good video. Didactically on world class level, even with bad sound. 😛

[@amantinband]

Haha thanks Manuel 😅

[@Manolete919]

Excellent explanation!!

[@זוהרפפר]

Awesome stuff! Keep the DDD concepts coming :)

[@davidjiang7929]

Is there a full walkthrough tutorial on Buber Dinner? Would love to code along to understand the thought process better!

[@adrianvdhouten]

I've watched this video about 5 times now :)

[@alfonsdeda8912]

Great video! I have one question: In repository pattern if i have for example an aggregate root Post and one entity Comment that can't exist without a post, the only repository that i should create is PostRepository? Does this repository handle all operations on comments too? Does it make sense to have a method that only retrieve comment informations or have at least the postName or postId without other post's informationt, or should i return always the aggregate? CommentRepository doesn't make sense right? Thanks in advance.

[@davemasters]

Great video, curious to see how you combine DDD aggregates/entities/value objects with EF

[@amantinband]

I struggled and learned a lot bending EF for DDD. There is a lot to talk about and practically no advanced examples available so you can expect some deep dives 👍🏼

[@davemasters]

@@amantinband That is the same as my experience, and yes, there really is not much material out there for it. But EF core has come along way in recent years allowing for constructors, automatic mapping to encapsulated backing fields, 'OwnsOne/OwnsMany' etc. Before these features the only way was to have a separate data model from the domain model which adds massive overhead.

[@amantinband]

Yeah exactly. It’s still not perfect IMO but definitely something we can work with!

[@pilotboba]

Vladimir Khorikov has a great course on Pluralsight about this topic.

[@davemasters]

@@pilotboba thanks, will check that out!

[@lilililliilil]

ty for the video man!!! Wish u best of luck ❤

[@amantinband]

Glad you liked it 😁

[@tiagorodrigues6284]

stupid question, if we only have private setters does that means that mappers and deserializers wont work directly?

[@siemen3539]

Would love to see a video covering DDD with a framework like Spring Boot! I would be curious in particular as to how you would handle the separation of domain logic from persistence/framework code.

[@amantinband]

I’m not familiar with spring boot, but the application we’re building out uses ASP.NET, and the principles we’ll use for separating logic between the layers should stay true regardless of the framework. There might be specific Java/persistence framework limitations, of course, but generally speaking, you should be able to apply what we’ll cover regardless of the framework 🙂

[@Huholoman]

What if i make DinnerAggregateRoot and DinnerReservationsAggregateRoot with same id or with relation by having DinnerReservationsId in DinnerAggregateRoot?

[@jodainemoore8300]

Could you do a Video with DDD Domain + Strategy Pattern please?

[@picious]

Thank you for your videos,, I just wanted to share with you that your voice is distorted - also in your previous video was the same. You changed something?

[@amantinband]

Yeah sorry about that, had it misconfigured. Next video should be fixed 🤞

[@camcommute]

can u have a one to many from one aggregates to another? or many to many

[@amantinband]

Yes, but aggregates only reference other aggregates by ID

[@rededu5356]

Good day sir, why is the Price an object? And when to decide if it should be an object or primitive type for properties? more power to you sir. thanks

[@PaulSebastianM]

You can reference other aggregates by a reference to the aggregate root, not just its ID (in the storage model you can store just the other aggregate's ID). I think most examples use IDs but technically, isn't holding a memory reference to the AR safe? Because you're just holding a reference to the transaction boundary of that AR, and you can only modify it through its public interface. Right?

[@amantinband]

Can you? Yes. Is it recommended? No. Check out this article by vaughn vernon where he talks about this issue: www.dddcommunity.org/wp-content/uploads/files/pdf_articles/Vernon_2011_2.pdf

[@PaulSebastianM]

The aggregate modeling steps are misleading and/or confusing. Not all entities have to be defined as aggregates. Why merge different aggregates into one aggregate? Aggregates have their own invariants, so do entities, but using these terms interchangeably leads to confusion. What does merging them achieve? Did you mean merge different *entities* to form aggregates in order to enforce a new aggregate's invariants (e.g. move Reservation *entity* inside the Dinner entity to form a Dinner aggregate that enforces invariants that use both these entities)?

[@amantinband]

Perhaps I could have been clearer on this topic. The steps I suggest in the video are: 1. Treat each entity as if it is an Aggregate Root 2. Merge Aggregates when there are constraints. Constraints can be: 1. Invariants 2. Eventual consistency cannot be tolerated Does that make sense?

[@botyironcastle]

what if you have huge data like 100000000comments in Post object. I don't think you can init a domain object with that much... looks useless to me when dealing with large chunks of data. Thoughts?

[@ibrahimkoz1983]

You're amazing.

[@OmprakashYadavIIT]

Awesome

[@amantinband]

Thanks Omprakash 🤙🏼

[@kenrazo2533]

learn a lot mate! woohooo

[@amantinband]

Thanks, Ken 🫶

[@janhendrikschreier]

hi Amichai, I assume you made a bunch of videos where the clipping of your audio happend and you publish this videos now on a weekly basis. If this is the case, please ignore this comment. If not: you're still clipping :/

[@amantinband]

Yeah, too bad I didn’t notice before. Sorry for that 🙏🏼 Next week the audio should improve

[@PaulSebastianM]

When panning, try being less "instant". It's OK when you do it because you anticipate it, but for an audience it's jarring and unexpected and makes you loose your focus for a second while you readjust. It's worse when the image is highly zoomed in and the main content that you should be focused on is basically covering the full screen.

[@amantinband]

That’s great feedback. Thanks Paul 🙏🏼

[@PaulSebastianM]

@@amantinband Thanks for listening. Keep improving!

[@Petoj87]

Love the video but the sound is off

[@MohamedAbdulRaouf]

I stand with Palstine

[@gretavanskeet2974]

Ive never seen someone with such a nice mic have such horrible audio.

[@clashclan4739]

The more I learn about DDD, the more it don't make much sense. Only theoretically it is good

[@felipemfrudeli]

Make sense only if you have a large system with multiple languages between the contexts. Imagine two types of Costumer, but the meaning is different for each context, if you only put them all together it will become more complex to handle with. For me, the most useful thing it's about the separation of concern and purity in domains, if you want to switch the technology like ORM or API, it's easier to change without modify the domain. The more complex types can also help the validation and discovery hidden business logic.

[@clashclan4739]

@felipemfrudeli how often did u change orm and database in .net?