📄 tanstack/query/v4/docs/framework/react/guides/dependent-queries

Dependent (or serial) queries depend on previous ones to finish before they can execute. To achieve this, it's as easy as using the enabled option to tell a query when it is ready to run:

tsx

// Get the user
const { data: user } = useQuery({
  queryKey: ['user', email],
  queryFn: getUserByEmail,
})

const userId = user?.id

// Then get the user's projects
const {
  status,
  fetchStatus,
  data: projects,
} = useQuery({
  queryKey: ['projects', userId],
  queryFn: getProjectsByUser,
  // The query will not execute until the userId exists
  enabled: !!userId,
})


// Get the user
const { data: user } = useQuery({
  queryKey: ['user', email],
  queryFn: getUserByEmail,
})

const userId = user?.id

// Then get the user's projects
const {
  status,
  fetchStatus,
  data: projects,
} = useQuery({
  queryKey: ['projects', userId],
  queryFn: getProjectsByUser,
  // The query will not execute until the userId exists
  enabled: !!userId,
})

The projects query will start in:

tsx

status: 'loading'
fetchStatus: 'idle'


status: 'loading'
fetchStatus: 'idle'

As soon as the user is available, the projects query will be enabled and will then transition to:

tsx

status: 'loading'
fetchStatus: 'fetching'


status: 'loading'
fetchStatus: 'fetching'

Once we have the projects, it will go to:

tsx

status: 'success'
fetchStatus: 'idle'


status: 'success'
fetchStatus: 'idle'

useQueries dependent Query
--------------------------

Dynamic parallel query - useQueries can depend on a previous query also, here's how to achieve this:

tsx

// Get the users ids
const { data: userIds } = useQuery({
  queryKey: ['users'],
  queryFn: getUsersData,
  select: users => users.map(user => user.id),
})

// Then get the users messages
const usersMessages = useQueries({
  queries: userIds
    ? userIds.map(id => {
        return {
          queryKey: ['messages', id],
          queryFn: () => getMessagesByUsers(id),
        };
      })
  : [], // if users is undefined, an empty array will be returned
})


// Get the users ids
const { data: userIds } = useQuery({
  queryKey: ['users'],
  queryFn: getUsersData,
  select: users => users.map(user => user.id),
})

// Then get the users messages
const usersMessages = useQueries({
  queries: userIds
    ? userIds.map(id => {
        return {
          queryKey: ['messages', id],
          queryFn: () => getMessagesByUsers(id),
        };
      })
  : [], // if users is undefined, an empty array will be returned
})

Note that useQueries return an array of query results

Edit on GitHub

Parallel Queries

Background Fetching Indicators

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