Function registerEntityForDerievedChanges

core/queryIndex.ts:183–202

(entity: TargetEntity)

  const entityDerievationWatching = new WeakMap<TargetEntity, () => void>();

  function registerEntityForDerievedChanges(entity: TargetEntity) {
    updateItemIndex(entity);
    if (entityDerievationWatching.has(entity)) {
      // Should not happen, but if does - could cause big bottlenecks
      console.warn("Bad state");
      return;
    }

    // Observe entity key using mobx
    // Note - this is lazy so will not be called initially until actual change happens
    const stop = observe(entity, key, (change) => {
      // We can use updateItemIndexWithValue as we know new value in change mobx event. This saves us computing the value twice if it is not cached.
      updateItemIndexWithValue(entity, change.newValue as TargetValue);
    });

    cleanup.next = stop;

    // Save cleanup and mark entity as already observed
    entityDerievationWatching.set(entity, stop);
  }

  function stopWatchingEntityForDerievedChange(entity: TargetEntity) {
    removeItemFromIndex(entity);