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RxJS relationships pipe operator

relationships is a RxJS pipe operator which is useful when we already have a stream of existing entities and would like to extend them with relationships.

For that we need:

  • the store object
  • a root selector with relationships we want to apply
  • an observable stream of entities

Let's pretend that we have a user$ stream which emits a user entity time to time. Then, we could extend the emitted entity in the next way in order to get it with relationships.

const userWithRelationships$ = user$.pipe(
  // a user w/o relationships.
  relationships(store, selectUser),
  // now a user w/ relationships.
);

The same can be done for a stream which emits an array of users. In this case, the root selector for arrays should be used.

const usersWithRelationships$ = users$.pipe(
  // users w/o relationships.
  relationships(store, selectUsers),
  // now users w/ relationships.
);