Vue DB

This skill builds on db-core. Read it first for collection setup, query builder, and mutation patterns.

TanStack DB — Vue

Setup

<script setup lang="ts">
import { useLiveQuery, eq, not } from '@tanstack/vue-db'

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

<template>
  <div v-if="isLoading">Loading...</div>
  <ul v-else>
    <li v-for="todo in todos" :key="todo.id">{{ todo.text }}</li>
  </ul>
</template>

@tanstack/vue-db re-exports everything from @tanstack/db.

Hook

useLiveQuery

All return values are ComputedRef:

// Query function with reactive deps
const minPriority = ref(5)
const { data, isLoading, isReady, status } = useLiveQuery(
  (q) =>
    q
      .from({ todo: todoCollection })
      .where(({ todo }) => gt(todo.priority, minPriority.value)),
  [minPriority],
)

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

// Pre-created collection (reactive via ref)
const { data } = useLiveQuery(preloadedCollection)

// Conditional query
const userId = ref<number | null>(null)
const { data, status } = useLiveQuery(
  (q) => {
    if (!userId.value) return undefined
    return q
      .from({ todo: todoCollection })
      .where(({ todo }) => eq(todo.userId, userId.value))
  },
  [userId],
)

Vue-Specific Patterns

Reactive dependencies with refs

const filter = ref('active')
const { data } = useLiveQuery(
  (q) =>
    q
      .from({ todo: todoCollection })
      .where(({ todo }) => eq(todo.status, filter.value)),
  [filter],
)
// Query re-runs when filter.value changes

Mutations in event handlers

const handleToggle = (id: number) => {
  todoCollection.update(id, (draft) => {
    draft.completed = !draft.completed
  })
}

Includes (Hierarchical Data)

When a query uses includes (subqueries in select), each child field is a live Collection by default. Subscribe to it with useLiveQuery in a subcomponent:

<!-- ProjectList.vue -->
<script setup lang="ts">
import { useLiveQuery, eq } from '@tanstack/vue-db'

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 })),
  })),
)
</script>

<template>
  <div v-for="project in projects" :key="project.id">
    {{ project.name }}
    <IssueList :issues-collection="project.issues" />
  </div>
</template>

<!-- IssueList.vue — subscribes to the child Collection -->
<script setup lang="ts">
import { useLiveQuery } from '@tanstack/vue-db'
import type { Collection } from '@tanstack/db'

const props = defineProps<{ issuesCollection: Collection }>()
const { data: issues } = useLiveQuery(() => props.issuesCollection)
</script>

<template>
  <ul>
    <li v-for="issue in issues" :key="issue.id">{{ issue.title }}</li>
  </ul>
</template>

With toArray(), child results are plain arrays and the parent re-emits on child changes:

import { toArray, eq } from '@tanstack/vue-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 a plain array — no subcomponent needed

See db-core/live-queries/SKILL.md for full includes rules (correlation conditions, nested includes, aggregates).

Common Mistakes

CRITICAL Missing reactive deps in dependency array

Wrong:

const userId = ref(1)
const { data } = useLiveQuery((q) =>
  q
    .from({ todo: todoCollection })
    .where(({ todo }) => eq(todo.userId, userId.value)),
)

Correct:

const userId = ref(1)
const { data } = useLiveQuery(
  (q) =>
    q
      .from({ todo: todoCollection })
      .where(({ todo }) => eq(todo.userId, userId.value)),
  [userId],
)

Reactive refs used in the query must be included in the deps array for the query to re-run on changes.

Source: docs/framework/vue/overview.md

See also: db-core/live-queries/SKILL.md — for query builder API.

See also: db-core/mutations-optimistic/SKILL.md — for mutation patterns.