Entity state selector

An entity state selector can be:

• an object which contains selectors {collection: selector, id: selector}
• a function that returns EntityState<T> like in NGRX
• an instance of EntityCollectionService<T> like in NGRX
• an instance of EntityCollectionServiceBase<T> like in NGRX

The first case is useful when the id key of an entity is not id, but another one: Id, uuid, etc. Then you can define here the key name, or a function which returns its value from an entity.

const selector1 = {
  collection: createFeatureSelector('users'),
  id: 'Id',
};
const selector2 = {
  collection: state => state.companies,
  id: 'uuid',
};
const selector3 = {
  collection: stateKeys(
    createFeatureSelector('addresses'),
    'byIds',
    'existingIds',
  ),
  id: entity => entity.uuid,
};