Initial Query Data

const todosQuery = useQuery(() => ({
  queryKey: ['todos'],
  queryFn: () => fetch('/todos'),
  initialData: initialTodos,
}))

// Will show initialTodos immediately, but also immediately refetch todos after mount
const todosQuery = useQuery(() => ({
  queryKey: ['todos'],
  queryFn: () => fetch('/todos'),
  initialData: initialTodos,
}))

// Show initialTodos immediately, but won't refetch until another interaction event is encountered after 1000 ms
const todosQuery = useQuery(() => ({
  queryKey: ['todos'],
  queryFn: () => fetch('/todos'),
  initialData: initialTodos,
  staleTime: 1000,
}))

// Show initialTodos immediately, but won't refetch until another interaction event is encountered after 1000 ms
const todosQuery = useQuery(() => ({
  queryKey: ['todos'],
  queryFn: () => fetch('/todos'),
  initialData: initialTodos,
  staleTime: 60 * 1000, // 1 minute
  // This could be 10 seconds ago or 10 minutes ago
  initialDataUpdatedAt: initialTodosUpdatedTimestamp, // eg. 1608412420052
}))

const todosQuery = useQuery(() => ({
  queryKey: ['todos'],
  queryFn: () => fetch('/todos'),
  initialData: () => getExpensiveTodos(),
}))

const todoQuery = useQuery(() => ({
  queryKey: ['todo', todoId],
  queryFn: () => fetch('/todos'),
  initialData: () => {
    // Use a todo from the 'todos' query as the initial data for this todo query
    return queryClient.getQueryData(['todos'])?.find((d) => d.id === todoId)
  },
}))

const todoQuery = useQuery(() => ({
  queryKey: ['todos', todoId],
  queryFn: () => fetch(`/todos/${todoId}`),
  initialData: () =>
    queryClient.getQueryData(['todos'])?.find((d) => d.id === todoId),
  initialDataUpdatedAt: () =>
    queryClient.getQueryState(['todos'])?.dataUpdatedAt,
}))

const todoQuery = useQuery(() => ({
  queryKey: ['todo', todoId],
  queryFn: () => fetch(`/todos/${todoId}`),
  initialData: () => {
    // Get the query state
    const state = queryClient.getQueryState(['todos'])

    // If the query exists and has data that is no older than 10 seconds...
    if (state && Date.now() - state.dataUpdatedAt <= 10 * 1000) {
      // return the individual todo
      return state.data.find((d) => d.id === todoId)
    }

    // Otherwise, return undefined and let it fetch from a hard loading state!
  },
}))