Tanstack DB

import { useLiveQuery, eq, not } from '@octanejs/tanstack-db'

function TodoList() {
  const { data: todos, isLoading } = useLiveQuery((q) =>
    q
      .from({ todo: todoCollection })
      .where(({ todo }) => not(todo.completed))
      .orderBy(({ todo }) => todo.created_at, 'asc'),
  )

  if (isLoading) return <div>Loading...</div>

  return (
    <ul>
      {todos.map((todo) => (
        <li key={todo.id}>{todo.text}</li>
      ))}
    </ul>
  )
}

// Query function with dependency array
const {
  data,
  state,
  collection,
  status,
  isLoading,
  isReady,
  isError,
  isIdle,
  isCleanedUp,
} = useLiveQuery(
  (q) =>
    q
      .from({ todo: todoCollection })
      .where(({ todo }) => eq(todo.userId, userId)),
  [userId],
)

// Config object
const { data } = useLiveQuery({
  query: (q) => q.from({ todo: todoCollection }),
  gcTime: 60000,
})

// Pre-created collection (from route loader)
const { data } = useLiveQuery(preloadedCollection)

// Conditional query — return undefined/null to disable
const { data, status } = useLiveQuery(
  (q) => {
    if (!userId) return undefined
    return q
      .from({ todo: todoCollection })
      .where(({ todo }) => eq(todo.userId, userId))
  },
  [userId],
)
// When disabled: status='disabled', data=undefined

// data is ALWAYS defined — never undefined
// Must wrap in <Suspense> and <ErrorBoundary>
function TodoList() {
  const { data: todos } = useLiveSuspenseQuery((q) =>
    q.from({ todo: todoCollection }),
  )

  return (
    <ul>
      {todos.map((t) => (
        <li key={t.id}>{t.text}</li>
      ))}
    </ul>
  )
}

// With deps — re-suspends when deps change
const { data } = useLiveSuspenseQuery(
  (q) =>
    q
      .from({ todo: todoCollection })
      .where(({ todo }) => eq(todo.category, category)),
  [category],
)

const { data, fetchNextPage, hasNextPage, isFetchingNextPage } =
  useLiveInfiniteQuery(
    (q) =>
      q
        .from({ posts: postsCollection })
        .where(({ posts }) => eq(posts.category, category))
        .orderBy(({ posts }) => posts.createdAt, 'desc'),
    { pageSize: 20 },
    [category],
  )

// data is the flat array of all loaded pages
// fetchNextPage() loads the next page
// hasNextPage is true when more data is available

import { usePacedMutations, debounceStrategy } from "@octanejs/tanstack-db"

const mutate = usePacedMutations({
  onMutate: (value: string) => {
    noteCollection.update(noteId, (draft) => {
      draft.content = value
    })
  },
  mutationFn: async ({ transaction }) => {
    await api.notes.update(noteId, transaction.mutations[0].changes)
  },
  strategy: debounceStrategy({ wait: 500 }),
})

// In handler:
<textarea onChange={(e) => mutate(e.target.value)} />

import { useLiveQueryEffect, eq } from '@octanejs/tanstack-db'

// Fire side effects when rows enter, exit, or update a query result.
// No render output — the effect is created on mount, disposed on unmount,
// and recreated when deps change.
function ChatComponent() {
  useLiveQueryEffect(
    {
      query: (q) =>
        q.from({ msg: messages }).where(({ msg }) => eq(msg.role, 'user')),
      skipInitial: true,
      onEnter: async (event) => {
        await generateResponse(event.value)
      },
    },
    [],
  )

  return <div>...</div>
}

function ProjectList() {
  const { data: projects } = useLiveQuery((q) =>
    q.from({ p: projectsCollection }).select(({ p }) => ({
      id: p.id,
      name: p.name,
      issues: q
        .from({ i: issuesCollection })
        .where(({ i }) => eq(i.projectId, p.id))
        .select(({ i }) => ({ id: i.id, title: i.title })),
    })),
  )

  return (
    <ul>
      {projects.map((project) => (
        <li key={project.id}>
          {project.name}
          <IssueList issuesCollection={project.issues} />
        </li>
      ))}
    </ul>
  )
}

// Child component subscribes to the child Collection
function IssueList({ issuesCollection }) {
  const { data: issues } = useLiveQuery(issuesCollection)
  return (
    <ul>
      {issues.map((issue) => (
        <li key={issue.id}>{issue.title}</li>
      ))}
    </ul>
  )
}

import { toArray, eq } from '@octanejs/tanstack-db'

const { data: projects } = useLiveQuery((q) =>
  q.from({ p: projectsCollection }).select(({ p }) => ({
    id: p.id,
    name: p.name,
    issues: toArray(
      q
        .from({ i: issuesCollection })
        .where(({ i }) => eq(i.projectId, p.id))
        .select(({ i }) => ({ id: i.id, title: i.title })),
    ),
  })),
)
// project.issues is Array<{ id, title }> — no subcomponent needed

const { data } = useLiveQuery(
  (q) =>
    q
      .from({ todo: todoCollection })
      .where(({ todo }) => eq(todo.$synced, false)),
  [],
)
// Shows only optimistic (unconfirmed) todos

// Include ALL external reactive values
const { data } = useLiveQuery(
  (q) =>
    q
      .from({ todo: todoCollection })
      .where(({ todo }) =>
        and(eq(todo.userId, userId), eq(todo.status, filter)),
      ),
  [userId, filter],
)

// Empty array = static query, never re-runs
const { data } = useLiveQuery((q) => q.from({ todo: todoCollection }), [])

// No array = re-runs on every render (usually wrong)

<ErrorBoundary fallback={<div>Error</div>}>
  <Suspense fallback={<div>Loading...</div>}>
    <TodoList />
  </Suspense>
</ErrorBoundary>

// In route loader:
await todoCollection.preload()

// In component — data available immediately:
const { data } = useLiveQuery((q) => q.from({ todo: todoCollection }))

const { data } = useLiveQuery((q) =>
  q.from({ todo: todoCollection }).where(({ todo }) => eq(todo.userId, userId)),
)

const { data } = useLiveQuery(
  (q) =>
    q
      .from({ todo: todoCollection })
      .where(({ todo }) => eq(todo.userId, userId)),
  [userId],
)

<Suspense fallback={<div>Loading...</div>}>
  <TodoList /> {/* uses useLiveSuspenseQuery */}
</Suspense>

<ErrorBoundary fallback={<div>Error</div>}>
  <Suspense fallback={<div>Loading...</div>}>
    <TodoList />
  </Suspense>
</ErrorBoundary>