craftEffect

An effect that can resolve craft dependencies with yield*.

Use it when a side effect needs a service. Not as a way to sync state — if a value is a function of another, derive it with computed instead of writing it from an effect.

Import

import { craftEffect } from '@craft-ng/core';

craftEffect('myEffect', function* () {
  const counter = yield* Counter();
  // do some stuff
});

Resource triggers

In generator code, primitive triggers are yieldable and must be consumed with yield*:

function* submit(term: string) {
  yield* searchQuery.call(term);
  yield* saveMutation.mutate({ term });
  yield* validateProcess.method(term);
}

Imperative triggers from ordinary UI callbacks remain valid:

button({ click: () => saveMutation.mutate({ term: input() }) }, 'Save');

Do not use those triggers as dependencies of a craftEffect. Prefer a declarative params signal, a source$, or a mutation/query insertion. The craft-ng/no-imperative-craft-resource-trigger rule also follows a craftGen, so wrapping the call does not bypass the restriction:

const triggerSearch = craftGen(function* (term: string) {
  yield* searchQuery.call(term);
});

craftEffect('load', function* () {
  yield* triggerSearch(input()); // forbidden: indirect imperative trigger
});

Use a reactive query instead when the data depends on a signal:

const user = yield* query('user', {
    params: userId,
    loader: ({ params }) => fetchUser(params),
  });

See Also

• craftComputed
• craftMethod
• Local state — deriving instead of writing from an effect