Data Client React

Rendering

// GET https://jsonplaceholder.typicode.com/todos/5
const todo = useSuspense(TodoResource.get, { id: 5 });
// GET https://jsonplaceholder.typicode.com/todos
const todoList = useSuspense(TodoResource.getList);
// GET https://jsonplaceholder.typicode.com/todos?userId=1
const todoListByUser = useSuspense(TodoResource.getList, { userId: 1 });
// subscriptions with polling, websockets or SSE
const todo = useLive(TodoResource.get, { id: 5 });
// without fetch
const todo = useCache(TodoResource.get, { id: 5 });
const todo = useQuery(Todo, { id: 5 });
// fetch without Suspense - returns { data, loading, error }
const { data, loading, error } = useDLE(TodoResource.get, { id: 5 });
// subscribe without Suspense (use with useSuspense or useDLE)
useSubscription(TodoResource.get, { id: 5 });
// parallel fetches with React.use()
const postPromise = useFetch(PostResource.get, { id });
const commentsPromise = useFetch(CommentResource.getList, { postId: id });
const post = use(postPromise);
const comments = use(commentsPromise);

For API definitions (like TodoResource), apply the skill "data-client-rest".

Mutations

const ctrl = useController();
// PUT https://jsonplaceholder.typicode.com/todos/5
const updateTodo = todo => ctrl.fetch(TodoResource.update, { id }, todo);
// PATCH https://jsonplaceholder.typicode.com/todos/5
const partialUpdateTodo = todo =>
  ctrl.fetch(TodoResource.partialUpdate, { id }, todo);
// POST https://jsonplaceholder.typicode.com/todos
const addTodoToBeginning = todo =>
  ctrl.fetch(TodoResource.getList.unshift, todo);
// POST https://jsonplaceholder.typicode.com/todos?userId=1
const addTodoToEnd = todo => ctrl.fetch(TodoResource.getList.push, { userId: 1 }, todo);
// DELETE https://jsonplaceholder.typicode.com/todos/5
const deleteTodo = id => ctrl.fetch(TodoResource.delete, { id });
// GET https://jsonplaceholder.typicode.com/todos?userId=1&page=2
const getNextPage = (page) => ctrl.fetch(TodoResource.getList.getPage, { userId: 1, page })

Helpful hooks

const [handleSubmit, loading, error] = useLoading(
  async data => {
    const post = await ctrl.fetch(PostResource.getList.push, data);
    navigateToPost(post.id);
  },
  [ctrl],
);

const [query, setQuery] = React.useState('');
const handleChange = e => setQuery(e.currentTarget.value);
const [debouncedQuery, isPending] = useDebounce(query, 200);

return (
  <AsyncBoundary fallback={<Loading />}>
    <IssueList query={debouncedQuery} owner="facebook" repo="react" />
  </AsyncBoundary>
)

Components

Prefer using AsyncBoundary for error handling and loading states unless the codebase has a custom AsyncBoundary that already combines Suspense and ErrorBoundary. Its props are fallback, errorComponent, and errorClassName and listen. It can be used to wrap any component that fetches data.

<AsyncBoundary listen={history.listen}>
  <TodoList />
</AsyncBoundary>

Type-safe imperative actions

Controller is returned from useController(). It has: ctrl.fetch(), ctrl.fetchIfStale(), ctrl.expireAll(), ctrl.invalidate(), ctrl.invalidateAll(), ctrl.setResponse(), ctrl.set(), ctrl.setError(), ctrl.resetEntireStore(), ctrl.subscribe(), ctrl.unsubscribe().

Programmatic queries

const queryRemainingTodos = new Query(
  TodoResource.getList.schema,
  entries => entries.filter(todo => !todo.completed).length,
);

const allRemainingTodos = useQuery(queryRemainingTodos);
const firstUserRemainingTodos = useQuery(queryRemainingTodos, { userId: 1 });

const groupTodoByUser = new Query(
  TodoResource.getList.schema,
  todos => Object.groupBy(todos, todo => todo.userId),
);
const todosByUser = useQuery(groupTodoByUser);

Browser Debugging (Chrome DevTools MCP)

To inspect store state, track dispatched actions, or invoke Controller methods from a browser MCP (user-chrome-devtools), see devtools-debugging. Uses globalThis.__DC_CONTROLLERS__ available in dev mode.

Managers

Custom Managers allow for global side effect handling. This is useful for webosckets, SSE, logging, etc. Always use the skill "data-client-manager" when writing managers.

Best Practices & Notes

• useDebounce(query, timeout) when rendering async data based on user field inputs
• [handleSubmit, loading, error] = useLoading() when tracking async mutations
• Prefer smaller React components that do one thing
• Co-locate data bindings: call useSuspense/useDLE/useCache/useQuery in the component that renders the data — don't prop drill
• Don't hide data bindings inside custom hooks: wrapping them obfuscates a component's data dependencies and couples data logic to view code, causing drift. Put tightly coupled data transformations in a Query schema (with the data model, e.g. src/resources/) so they stay reusable and evolve independently of views

References

For detailed API documentation, see the references directory:

• useSuspense;_pagination.md - Fetch with Suspense
• useFetch - Fetch for React.use() and parallel loading
• useQuery - Read from cache without fetch
• useCache - Read from cache (nullable)
• useLive;_useLive.md - Fetch + subscribe to updates
• useDLE - Fetch without Suspense (returns data/loading/error)
• useSubscription - Subscribe to updates (polling/websocket/SSE)
• useController - Access Controller
• Controller - Imperative actions
• AsyncBoundary;_AsyncBoundary.md - Error/loading boundary
• useLoading;_useLoading.md - Track async mutation state
• useDebounce - Debounce values
• DataProvider - Root provider
• data-dependency - Rendering guide
• mutations;_VoteDemo.md - Mutations guide
• Actions - Store action types (FETCH, SET, etc.)
• devtools-debugging - Debug with Chrome DevTools MCP

ALWAYS follow these patterns and refer to the official docs for edge cases. Prioritize code generation that is idiomatic, type-safe, and leverages automatic normalization/caching via skill "data-client-schema" definitions.