Handling missing entry in related entity state

[nbitouze]

Let's say I have a Book entity like

interface Book {
 authorId: string;
 author: Author;
 // ...
}

I can use relatedEntitySelector and combine it with rootEntity to get a selector that returns books where the authorId field has been automatically looked up in my Author state to hydrate the author field.

Now let's say that' I have too many authors to load them all upfront. The authorId will most likely not find an entity matching authorId. It would be great to have a way to detect these misses.

I think that what currently happens in the callback defined in relatedEntity is that simply ignore the issue:

        // Line ~120 in relatedEntity.ts
        const valueEntities = [];
        for (const id of ids) {
            if (!featureState.entities[id]) {
                continue; // Ignore related ids that don't appear in the matching feature state
            }

            // ...

            entityValue = {...featureState.entities[id]} as RELATED_ENTITY;

            // ...

            valueEntities.push(entityValue);
        }

Is there any suggestion or best practice to do that? If I haven't missed any build-in functionality, I guess my options are:

• Put all of this logic further down the line once the selectors have returned my entities. Unfortunately at that point I need to define my relationships again, I can't just build upon what I've defined with relatedEntitySelector.
• Re-define relatedEntity and before the above continue statement, do something interesting (most likely call a user-defined function).

Thank you.