`KeyValueTemplate` assumes a map only and tries to assign ID [DATAKV-127]

[spring-projects-issues]

Wallace Wadge opened DATAKV-127 and commented

Apologies for the length of this post but before I explain my issue, a little discussion is in order (I think this would be a great example project actually). I like Spring Data Rest, but I don't want to expose my DB objects as my api to allow me to modify my DB without affecting my api. My DB code also lives in a separate isolated module.

I have 2 modules, a web front-end and a core; so for eg I have a Client class for my DB and ApiClient for my api. Now Spring Data KeyValue allows me to treat a map as a repository -- Great! So on web module I define my repositories + API entities and on backend I have completely different repositories, and because I have a common interface my backend mapping code is very simple, for eg:

class Foo implements KeyValueAdapter { ....
    @Override
    public boolean contains(Serializable id, Serializable keyspace) {
        boolean result = false;
        try {
            Repository repo = getRepositoryFor(keyspace.toString());

            Class<?> modelClass = apiToModelClass(keyspace); // just a naming convention

           Path<Number> idPath = path(Number.class, path(modelClass, (String)keyspace), "id");
            Predicate mainPredicate = predicate(Ops.EQ, idPath, Expressions.constant(id));

            result = ((QueryDslPredicateExecutor)repo).exists(allOf(mainPredicate, securityContextPredicate(modelClass)));
        } catch (ClassNotFoundException e) {
            log.error("Unable to invoke repo invoker for contains", e);
        }

        return result;
    }

I even map querydsl predicates between the two worlds which is very nice too, everything based on my single Api->DB model mapper (orika in my case).

Now for the problem:

KeyValueTemplate assumes I will always need to generate an ID to store in some map so IdentifierGenerator is hard-coded to DefaultIdentifierGenerator.INSTANCE; but in my case I want to send null to the other side because it will be filled later on by the db layer. Can you please:

• Allow us to override KeyValueTemplate identifierGenerator property
• Remove the assert in insert(...)
• Pass more meta-data/call an alternate adapter method since both insert and update call the same .put(..) method

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No further details from DATAKV-127