Relationship between `UserRepository` and `TypeormRepositoryBase`

While working through your database implementation, I was wondering why UserRepository does not use TypeormRepositoryBase.findOne?

https://github.com/Sairyss/domain-driven-hexagon/blob/0b55c3c290f197c920cb563add62e04f83faae96/src/modules/user/database/user.repository.ts#L35-L43

Shouldn’t we do this instead:

const emailVO = new Email(email);
const user = await this.findOne({ email: emailVO });
return user;

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And a second question: It seems like UserRepository.prepareQuery removes all query parameters except for id? Why?

https://github.com/Sairyss/domain-driven-hexagon/blob/0b55c3c290f197c920cb563add62e04f83faae96/src/modules/user/database/user.repository.ts#L61-L70

[Sairyss]

That’s right, you have to adjust either a type to accept only the parameters specified in prepareQuery, or modify Repository to your liking. I’ll think how to improve it in the future so it’s less confusing.

[estrehle]

Ah, I see! Now I understand why one would want a more flexible way of preparing queries.

My worry, however, is that this implementation suggests a generality that is not there. The repository exposes a method

findOne(params: QueryParams<EntityProps>)

where

type QueryParams<EntityProps> = DeepPartial<BaseEntityProps & EntityProps>

To anyone who has not studied prepareQuery in detail, this looks like a method that allows one to search the repository using arbitrary combinations of entity properties.

But when I call, say, UserRepository.findOne({ country: 'Germany' }) then the country param will be silently deleted and the result will be the same as if I had called UserRepository.findOne({ }). That could lead to nasty bugs.

My “solution” was to remove the find... methods (except for findById, which works the same for every entity) from TypeormRepositoryBase and resort to custom implementations in each repository, in the spirit of UserRepository.findOneByCountry(country: string).