Dependent queries

When one request needs the result of another (fetch a character, then its origin location), connectQuery wires them: when the source succeeds it computes the target's params and starts it. No sample boilerplate, no effect in a component.

One source

import { createQuery, connectQuery } from 'effector-refetch';

const characterQuery = createQuery({ effect: fetchCharacterFx, cache: true });
const originQuery = createQuery({ effect: fetchLocationFx, cache: { staleAfter: 60_000 } });

connectQuery({
  source: characterQuery,
  fn: ({ result: character }) => ({ params: { url: character.origin.url } }),
  target: originQuery,
});

characterQuery.start(1); // originQuery starts automatically when the character resolves

fn receives { result, params } of the source (the result, plus the params it ran with) and returns { params } for the target. It re-runs every time the source succeeds, so the target stays in sync — and since both are plain queries, cache / retry / concurrency apply to each independently.

Several sources

Pass an object of queries — the target starts once all of them are done, then again whenever any of them produces a fresh result:

connectQuery({
  source: { user: userQuery, settings: settingsQuery },
  fn: ({ user, settings }) => ({ params: { id: user.result.id, theme: settings.result.theme } }),
  target: dashboardQuery,
});

Each key in fn's argument is { result, params } for that source.

Gating with filter

filter skips the target run when the source result isn't usable yet (same { result, params } shape, return false to skip):

connectQuery({
  source: characterQuery,
  filter: ({ result: character }) => character.origin.url !== '', // unknown origin -> don't fetch
  fn: ({ result: character }) => ({ params: { url: character.origin.url } }),
  target: originQuery,
});

connectQuery vs combineQueries

• connectQuery — chains: a source feeds the next query's params (request B depends on A's result).
• combineQueries — aggregates: read several independent queries as one combined $data / $pending / $errors (the effector-flavored useQueries), with no dependency between them.

Runnable: examples/rick-and-morty.ts.