CODEWITHSUNDEEP
javaspringrestspring-mvcdomain-driven-design
Shem
Shem

Reputation: 565

Entity vs ValueObject

I'm creating a RESTful webservice, which retrieves repository details from github and returns them. My code looks like this:

@GetMapping(value = "/{owner}/{repositoryName}")
@ResponseStatus(HttpStatus.OK)
public RepositoryDetails getRepositoryDetails(@PathVariable String owner, @PathVariable String repositoryName) throws Exception {
    log.info("Github repository details request: owner: " + owner + ", repository name: " + repositoryName);
    checkParameters(owner, repositoryName);
    RepositoryDetailsInternal repositoryDetailsInternal = repoService.getRepositoryDetails(owner, repositoryName);
    RepositoryDetails repositoryDetailsOutput = new RepositoryDetails(repositoryDetailsInternal, LocaleContextHolder.getLocale());
    return repositoryDetailsOutput;
}

As you can see, there are two important objects: repositoryDetailsInternal and repositoryDetailsOutput. repositoryDetailsInternal is the parsed response data from Github and repositoryDetailsOutput is the output object returned by my webservice.
My question is: what is each of these objects - an entity or a value object?

I'm leaning towards calling repositoryDetailsInternal an entity and repositoryDetailsOutput a value object, but I'd like some second opinion on that.
On one hand, repositoryDetailsInternal is something that can be changed over time (stargazers count can increase or decrease), but on the other hand in my application this object is immutable.
EDIT: I should also mention that repositoryDetailsInternal is cached using owner and repository name, so it may be perceived as identity: 

@Cacheable(REPO_DETAILS_CACHE)
    public RepositoryDetailsInternal getRepositoryDetails(String owner, String repositoryName) throws TimeoutException  {...}



repositoryDetailsOutput is also immutable and seems like a value object, because it represents a kind of a snapshot of repository state.

Upvotes: 0

Views: 398

Answers (1)

Constantin Galbenu
Constantin Galbenu

Reputation: 17683

From what I can tell both objects are Value Objects even if the value returned by the web service can vary because they don't have an Identity.

I can imagine a more complex scenario in which they could become entities but I don't know if this is your case (i.e. you could store an evolution in time of the stars a project has).

Upvotes: 2

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