Resolvers

QuerySearchResolver classes are designed to enrich QueryFilter POJOs by incorporating data from external components before processing in the QuerySearch class. This is essential due to constraints where each component might be persisted in a different database, preventing direct cross-component queries as they are blocked by the persistence provider.

Example

Imagine you have the email address of a user in the account::User element, but you need their username in a query for an element in a different component. You would need to take the following steps in the QuerySearchResolver class:

1. Retrieve email: Retrieve the user's email address from the QueryFilter object.
2. Resolve user: Use the finder for the User element to find the user based on the email address.
3. Enrich filter: If the user was found, add their username to the QueryFilter object.

public CrudsResult<MyElementQueryFilter> resolve(
    ParameterContext<MyElementQueryFilter> queryFilterParameter) {
  final Context context = queryFilterParameter.getContext();
  final MyElementQueryFilter queryFilter = queryFilterParameter.getValue();

  // @anchor:resolve:start
  // @anchor:resolve:end
  // anchor:custom-resolve:start
  /* 1. Retrieve email */
  String email = queryFilter.getEmail();

  if (email != null) {
    /* 2. Resolve user */
    UserFindByEmailEqDetails finder = new UserFindByEmailEqDetails();
    finder.setEmail(email);

    SearchDetails<UserFindByEmailEqDetails> searchDetails =
      SearchDetails.fetchNDetails(finder, 1);
    UserAgent userAgent = UserAgent.getUserAgent(context);

    SearchResult<UserDetails> userSearchResult = userAgent.find(searchDetails);
    if (userSearchResult.isError()) {
      return CrudsResult.error(userSearchResult.getDiagnostics());
    }

    /* 3. Enrich filter */
    userSearchResult.getFirstResult().ifPresent(
        searchResult -> queryFilter.setUsername(searchResult.getName()));
  }
  // anchor:custom-resolve:end

  return CrudsResult.success(queryFilter);
}