Can Domain Service Access Repositories?

[Muhammad Bilal]

Hello Everyone!

I'm new to DDD. I have a scenario that I have some validations and some business rules which I need to perform, so I'm making some validation service(which is a domain service) and the service needs to access data from repository. So my question is that can we inject Repositories in Domain Service? Or should I pass the specific entities/VO to domain service which are needed for validation from Application Service? Please suggest me which approach is better?


Thanks,
Bilal

[@yreynhout]

Yes, a domain service can access repositories.

[Vincent van Dijk]

Using CQRS? Don't think it's a good idea to use aggregates for query purposes. Right?

Vincent.

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[Muhammad Bilal]

Thanks for the reply,

But I'm not using CQRS right now.

[Muhammad Bilal]

Alright Thanks :)

[Greg Young]

If possible I would prefer to pass in the domain objects but there are some scenarios that doesn't make sense.

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[Muhammad Bilal]

Yeah it seems more logical.

Thanks for the reply :)

On Tuesday, January 6, 2015 5:21:39 PM UTC+5, Greg Young wrote:

If possible I would prefer to pass in the domain objects but there are some scenarios that doesn't make sense.

On Tuesday, January 6, 2015, Muhammad Bilal <bilal...@gmail.com> wrote:

Hello Everyone!

I'm new to DDD. I have a scenario that I have some validations and some business rules which I need to perform, so I'm making some validation service(which is a domain service) and the service needs to access data from repository. So my question is that can we inject Repositories in Domain Service? Or should I pass the specific entities/VO to domain service which are needed for validation from Application Service? Please suggest me which approach is better?


Thanks,
Bilal

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[Greg Young]

Easier to test as well.

On Tuesday, January 6, 2015, Muhammad Bilal <bilal...@gmail.com> wrote:

Yeah it seems more logical.

Thanks for the reply :)

On Tuesday, January 6, 2015 5:21:39 PM UTC+5, Greg Young wrote:

If possible I would prefer to pass in the domain objects but there are some scenarios that doesn't make sense.

On Tuesday, January 6, 2015, Muhammad Bilal <bilal...@gmail.com> wrote:

Hello Everyone!

I'm new to DDD. I have a scenario that I have some validations and some business rules which I need to perform, so I'm making some validation service(which is a domain service) and the service needs to access data from repository. So my question is that can we inject Repositories in Domain Service? Or should I pass the specific entities/VO to domain service which are needed for validation from Application Service? Please suggest me which approach is better?


Thanks,
Bilal

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Studying for the Turing test

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[Muhammad Bilal]

Yes, exactly.

Thanks

[Rasheed Amir]

Hi Greg,

Can you please list those scenarios in which it won't make sense?

I will always prefer to pass in the domain objects instead of injecting repository into the domain service.

Thanks,

/Rasheed

On Tuesday, January 6, 2015 1:21:39 PM UTC+1, Greg Young wrote:

If possible I would prefer to pass in the domain objects but there are some scenarios that doesn't make sense.

On Tuesday, January 6, 2015, Muhammad Bilal <bilal...@gmail.com> wrote:

Hello Everyone!

I'm new to DDD. I have a scenario that I have some validations and some business rules which I need to perform, so I'm making some validation service(which is a domain service) and the service needs to access data from repository. So my question is that can we inject Repositories in Domain Service? Or should I pass the specific entities/VO to domain service which are needed for validation from Application Service? Please suggest me which approach is better?


Thanks,
Bilal

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[Greg Young]

I need many of them or I need summary information that I query from the repository eg how many blue tickets are currently open (I don't want the 900 blue tickets, just the count)

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[Rasheed Amir]

Got it thanks!

[Greg Young]

Search the list for any case where you put a helper method on a repo and they are the scenarios I am referring to.

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[Gabriel Palacios Moulergues]

I advocate using Repositories only in the Application layer.

Wouldn't the helper method on a repo be a sign that a new aggregate is needed and that a modeling opportunity has been missed?

If the currently open blue tickets count is needed to enforce a business rule, maybe you should load that into an aggregate to enforce that given rule?

If on the contrary, it is just needed for your Query side, you could build some read-only DAOs.