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变更

与查询不同，突变通常用于创建/更新/删除数据或执行服务器端副作用。为此，TanStack Query 导出了一个 useMutation 钩子。

这是一个将新待办事项添加到服务器的突变示例

tsx
function App() {
  const mutation = useMutation({
    mutationFn: (newTodo) => {
      return axios.post('/todos', newTodo)
    },
  })

  return (
    <div>
      {mutation.isPending ? (
        'Adding todo...'
      ) : (
        <>
          {mutation.isError ? (
            <div>An error occurred: {mutation.error.message}</div>
          ) : null}

          {mutation.isSuccess ? <div>Todo added!</div> : null}

          <button
            onClick={() => {
              mutation.mutate({ id: new Date(), title: 'Do Laundry' })
            }}
          >
            Create Todo
          </button>
        </>
      )}
    </div>
  )
}

function App() {
  const mutation = useMutation({
    mutationFn: (newTodo) => {
      return axios.post('/todos', newTodo)
    },
  })

  return (
    <div>
      {mutation.isPending ? (
        'Adding todo...'
      ) : (
        <>
          {mutation.isError ? (
            <div>An error occurred: {mutation.error.message}</div>
          ) : null}

          {mutation.isSuccess ? <div>Todo added!</div> : null}

          <button
            onClick={() => {
              mutation.mutate({ id: new Date(), title: 'Do Laundry' })
            }}
          >
            Create Todo
          </button>
        </>
      )}
    </div>
  )
}

突变在任何给定时刻只能处于以下状态之一

  • isIdle 或 status === 'idle' - 突变当前处于空闲或全新/重置状态
  • isPending 或 status === 'pending' - 突变当前正在运行
  • isError 或 status === 'error' - 突变遇到错误
  • isSuccess 或 status === 'success' - 突变成功，突变数据可用

除了这些主要状态之外，根据突变的状态，还可以获得更多信息

  • error - 如果突变处于 error 状态，则可以通过 error 属性获取错误。
  • data - 如果突变处于 success 状态，则可以通过 data 属性获取数据。

在上面的示例中，您还看到可以通过调用 mutate 函数并传入**单个变量或对象**来将变量传递给您的突变函数。

即使只有变量，突变也不是那么特殊，但当与 onSuccess 选项、Query Client 的 invalidateQueries 方法 和 Query Client 的 setQueryData 方法 结合使用时，突变会成为一个非常强大的工具。

重要提示：mutate 函数是一个异步函数，这意味着您不能在 **React 16 及更早版本**的事件回调中直接使用它。如果您需要在 onSubmit 中访问事件，则需要将 mutate 包装在另一个函数中。这是由于 React 事件池化。

tsx
// This will not work in React 16 and earlier
const CreateTodo = () => {
  const mutation = useMutation({
    mutationFn: (event) => {
      event.preventDefault()
      return fetch('/api', new FormData(event.target))
    },
  })

  return <form onSubmit={mutation.mutate}>...</form>
}

// This will work
const CreateTodo = () => {
  const mutation = useMutation({
    mutationFn: (formData) => {
      return fetch('/api', formData)
    },
  })
  const onSubmit = (event) => {
    event.preventDefault()
    mutation.mutate(new FormData(event.target))
  }

  return <form onSubmit={onSubmit}>...</form>
}

// This will not work in React 16 and earlier
const CreateTodo = () => {
  const mutation = useMutation({
    mutationFn: (event) => {
      event.preventDefault()
      return fetch('/api', new FormData(event.target))
    },
  })

  return <form onSubmit={mutation.mutate}>...</form>
}

// This will work
const CreateTodo = () => {
  const mutation = useMutation({
    mutationFn: (formData) => {
      return fetch('/api', formData)
    },
  })
  const onSubmit = (event) => {
    event.preventDefault()
    mutation.mutate(new FormData(event.target))
  }

  return <form onSubmit={onSubmit}>...</form>
}

重置突变状态

有时您需要清除突变请求的 error 或 data。为此，您可以使用 reset 函数来处理此问题

tsx
const CreateTodo = () => {
  const [title, setTitle] = useState('')
  const mutation = useMutation({ mutationFn: createTodo })

  const onCreateTodo = (e) => {
    e.preventDefault()
    mutation.mutate({ title })
  }

  return (
    <form onSubmit={onCreateTodo}>
      {mutation.error && (
        <h5 onClick={() => mutation.reset()}>{mutation.error}</h5>
      )}
      <input
        type="text"
        value={title}
        onChange={(e) => setTitle(e.target.value)}
      />
      <br />
      <button type="submit">Create Todo</button>
    </form>
  )
}

const CreateTodo = () => {
  const [title, setTitle] = useState('')
  const mutation = useMutation({ mutationFn: createTodo })

  const onCreateTodo = (e) => {
    e.preventDefault()
    mutation.mutate({ title })
  }

  return (
    <form onSubmit={onCreateTodo}>
      {mutation.error && (
        <h5 onClick={() => mutation.reset()}>{mutation.error}</h5>
      )}
      <input
        type="text"
        value={title}
        onChange={(e) => setTitle(e.target.value)}
      />
      <br />
      <button type="submit">Create Todo</button>
    </form>
  )
}

突变副作用

useMutation 附带了一些辅助选项，可以在突变生命周期的任何阶段快速轻松地产生副作用。这些对于 突变后使查询失效和重新获取 甚至 乐观更新 都很有用

tsx
useMutation({
  mutationFn: addTodo,
  onMutate: (variables) => {
    // A mutation is about to happen!

    // Optionally return a context containing data to use when for example rolling back
    return { id: 1 }
  },
  onError: (error, variables, context) => {
    // An error happened!
    console.log(`rolling back optimistic update with id ${context.id}`)
  },
  onSuccess: (data, variables, context) => {
    // Boom baby!
  },
  onSettled: (data, error, variables, context) => {
    // Error or success... doesn't matter!
  },
})

useMutation({
  mutationFn: addTodo,
  onMutate: (variables) => {
    // A mutation is about to happen!

    // Optionally return a context containing data to use when for example rolling back
    return { id: 1 }
  },
  onError: (error, variables, context) => {
    // An error happened!
    console.log(`rolling back optimistic update with id ${context.id}`)
  },
  onSuccess: (data, variables, context) => {
    // Boom baby!
  },
  onSettled: (data, error, variables, context) => {
    // Error or success... doesn't matter!
  },
})

当在任何回调函数中返回一个 promise 时，它将首先被 await，然后才会调用下一个回调。

tsx
useMutation({
  mutationFn: addTodo,
  onSuccess: async () => {
    console.log("I'm first!")
  },
  onSettled: async () => {
    console.log("I'm second!")
  },
})

useMutation({
  mutationFn: addTodo,
  onSuccess: async () => {
    console.log("I'm first!")
  },
  onSettled: async () => {
    console.log("I'm second!")
  },
})

您可能会发现在调用 mutate 时，您希望**触发附加回调**，而不仅仅是 useMutation 上定义的回调。这可用于触发特定于组件的副作用。为此，您可以在突变变量之后向 mutate 函数提供任何相同的回调选项。支持的选项包括：onSuccess、onError 和 onSettled。请记住，如果您的组件在突变完成**之前**卸载，则这些附加回调将不会运行。

tsx
useMutation({
  mutationFn: addTodo,
  onSuccess: (data, variables, context) => {
    // I will fire first
  },
  onError: (error, variables, context) => {
    // I will fire first
  },
  onSettled: (data, error, variables, context) => {
    // I will fire first
  },
})

mutate(todo, {
  onSuccess: (data, variables, context) => {
    // I will fire second!
  },
  onError: (error, variables, context) => {
    // I will fire second!
  },
  onSettled: (data, error, variables, context) => {
    // I will fire second!
  },
})

useMutation({
  mutationFn: addTodo,
  onSuccess: (data, variables, context) => {
    // I will fire first
  },
  onError: (error, variables, context) => {
    // I will fire first
  },
  onSettled: (data, error, variables, context) => {
    // I will fire first
  },
})

mutate(todo, {
  onSuccess: (data, variables, context) => {
    // I will fire second!
  },
  onError: (error, variables, context) => {
    // I will fire second!
  },
  onSettled: (data, error, variables, context) => {
    // I will fire second!
  },
})

连续突变

当涉及连续突变时，处理 onSuccess、onError 和 onSettled 回调略有不同。当它们传递给 mutate 函数时，它们只会**运行一次**，并且只有在组件仍然挂载的情况下才会运行。这是因为每当调用 mutate 函数时，都会删除并重新订阅突变观察者。相反，useMutation 处理程序会为每个 mutate 调用执行。

请注意，传递给 useMutation 的 mutationFn 很可能是异步的。在这种情况下，突变完成的顺序可能与 mutate 函数调用的顺序不同。

tsx
useMutation({
  mutationFn: addTodo,
  onSuccess: (data, variables, context) => {
    // Will be called 3 times
  },
})

const todos = ['Todo 1', 'Todo 2', 'Todo 3']
todos.forEach((todo) => {
  mutate(todo, {
    onSuccess: (data, variables, context) => {
      // Will execute only once, for the last mutation (Todo 3),
      // regardless which mutation resolves first
    },
  })
})

useMutation({
  mutationFn: addTodo,
  onSuccess: (data, variables, context) => {
    // Will be called 3 times
  },
})

const todos = ['Todo 1', 'Todo 2', 'Todo 3']
todos.forEach((todo) => {
  mutate(todo, {
    onSuccess: (data, variables, context) => {
      // Will execute only once, for the last mutation (Todo 3),
      // regardless which mutation resolves first
    },
  })
})

Promises

使用 mutateAsync 而不是 mutate 来获取一个在成功时解析或在错误时抛出的 promise。例如，这可以用于组合副作用。

tsx
const mutation = useMutation({ mutationFn: addTodo })

try {
  const todo = await mutation.mutateAsync(todo)
  console.log(todo)
} catch (error) {
  console.error(error)
} finally {
  console.log('done')
}

const mutation = useMutation({ mutationFn: addTodo })

try {
  const todo = await mutation.mutateAsync(todo)
  console.log(todo)
} catch (error) {
  console.error(error)
} finally {
  console.log('done')
}

重试

默认情况下，TanStack Query 不会在错误时重试突变，但可以使用 retry 选项进行重试。

tsx
const mutation = useMutation({
  mutationFn: addTodo,
  retry: 3,
})

const mutation = useMutation({
  mutationFn: addTodo,
  retry: 3,
})

如果修改因设备离线而失败，它们将在设备重新连接时以相同的顺序重试。

持久化修改。

突变可以在需要时持久化到存储中，并在稍后恢复。这可以通过 hydration 函数完成。

tsx
const queryClient = new QueryClient()

// Define the "addTodo" mutation
queryClient.setMutationDefaults(['addTodo'], {
  mutationFn: addTodo,
  onMutate: async (variables) => {
    // Cancel current queries for the todos list
    await queryClient.cancelQueries({ queryKey: ['todos'] })

    // Create optimistic todo
    const optimisticTodo = { id: uuid(), title: variables.title }

    // Add optimistic todo to todos list
    queryClient.setQueryData(['todos'], (old) => [...old, optimisticTodo])

    // Return context with the optimistic todo
    return { optimisticTodo }
  },
  onSuccess: (result, variables, context) => {
    // Replace optimistic todo in the todos list with the result
    queryClient.setQueryData(['todos'], (old) =>
      old.map((todo) =>
        todo.id === context.optimisticTodo.id ? result : todo,
      ),
    )
  },
  onError: (error, variables, context) => {
    // Remove optimistic todo from the todos list
    queryClient.setQueryData(['todos'], (old) =>
      old.filter((todo) => todo.id !== context.optimisticTodo.id),
    )
  },
  retry: 3,
})

// Start mutation in some component:
const mutation = useMutation({ mutationKey: ['addTodo'] })
mutation.mutate({ title: 'title' })

// If the mutation has been paused because the device is for example offline,
// Then the paused mutation can be dehydrated when the application quits:
const state = dehydrate(queryClient)

// The mutation can then be hydrated again when the application is started:
hydrate(queryClient, state)

// Resume the paused mutations:
queryClient.resumePausedMutations()

const queryClient = new QueryClient()

// Define the "addTodo" mutation
queryClient.setMutationDefaults(['addTodo'], {
  mutationFn: addTodo,
  onMutate: async (variables) => {
    // Cancel current queries for the todos list
    await queryClient.cancelQueries({ queryKey: ['todos'] })

    // Create optimistic todo
    const optimisticTodo = { id: uuid(), title: variables.title }

    // Add optimistic todo to todos list
    queryClient.setQueryData(['todos'], (old) => [...old, optimisticTodo])

    // Return context with the optimistic todo
    return { optimisticTodo }
  },
  onSuccess: (result, variables, context) => {
    // Replace optimistic todo in the todos list with the result
    queryClient.setQueryData(['todos'], (old) =>
      old.map((todo) =>
        todo.id === context.optimisticTodo.id ? result : todo,
      ),
    )
  },
  onError: (error, variables, context) => {
    // Remove optimistic todo from the todos list
    queryClient.setQueryData(['todos'], (old) =>
      old.filter((todo) => todo.id !== context.optimisticTodo.id),
    )
  },
  retry: 3,
})

// Start mutation in some component:
const mutation = useMutation({ mutationKey: ['addTodo'] })
mutation.mutate({ title: 'title' })

// If the mutation has been paused because the device is for example offline,
// Then the paused mutation can be dehydrated when the application quits:
const state = dehydrate(queryClient)

// The mutation can then be hydrated again when the application is started:
hydrate(queryClient, state)

// Resume the paused mutations:
queryClient.resumePausedMutations()

持久化离线突变

如果您使用 persistQueryClient 插件 持久化离线突变，那么除非您提供默认突变函数，否则页面重新加载时无法恢复突变。

这是一个技术限制。当持久化到外部存储时，只会持久化突变的状态，因为函数无法序列化。在 hydration 之后，触发突变的组件可能未挂载，因此调用 resumePausedMutations 可能会导致错误：No mutationFn found。

tsx
const persister = createSyncStoragePersister({
  storage: window.localStorage,
})
const queryClient = new QueryClient({
  defaultOptions: {
    queries: {
      gcTime: 1000 * 60 * 60 * 24, // 24 hours
    },
  },
})

// we need a default mutation function so that paused mutations can resume after a page reload
queryClient.setMutationDefaults(['todos'], {
  mutationFn: ({ id, data }) => {
    return api.updateTodo(id, data)
  },
})

export default function App() {
  return (
    <PersistQueryClientProvider
      client={queryClient}
      persistOptions={{ persister }}
      onSuccess={() => {
        // resume mutations after initial restore from localStorage was successful
        queryClient.resumePausedMutations()
      }}
    >
      <RestOfTheApp />
    </PersistQueryClientProvider>
  )
}

const persister = createSyncStoragePersister({
  storage: window.localStorage,
})
const queryClient = new QueryClient({
  defaultOptions: {
    queries: {
      gcTime: 1000 * 60 * 60 * 24, // 24 hours
    },
  },
})

// we need a default mutation function so that paused mutations can resume after a page reload
queryClient.setMutationDefaults(['todos'], {
  mutationFn: ({ id, data }) => {
    return api.updateTodo(id, data)
  },
})

export default function App() {
  return (
    <PersistQueryClientProvider
      client={queryClient}
      persistOptions={{ persister }}
      onSuccess={() => {
        // resume mutations after initial restore from localStorage was successful
        queryClient.resumePausedMutations()
      }}
    >
      <RestOfTheApp />
    </PersistQueryClientProvider>
  )
}

我们还有一个涵盖查询和突变的全面离线示例。

突变范围

默认情况下，所有突变并行运行——即使您多次调用同一突变的 .mutate()。突变可以给定一个带 id 的 scope 以避免这种情况。所有具有相同 scope.id 的突变将串行运行，这意味着当它们被触发时，如果该 scope 已经有一个突变正在进行中，它们将以 isPaused: true 状态开始。它们将被放入队列中，并在轮到它们时自动恢复。

tsx
const mutation = useMutation({
  mutationFn: addTodo,
  scope: {
    id: 'todo',
  },
})

const mutation = useMutation({
  mutationFn: addTodo,
  scope: {
    id: 'todo',
  },
})

延伸阅读

有关突变的更多信息，请参阅社区资源中的 #12：掌握 React Query 中的突变。

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Query.gg - The Official React Query Course - TanStack 中文
“如果你想*真正*理解 React Query，没有比 query.gg 更好的方法了。”—Tanner Linsley
想跳过文档吗？
Query.gg - The Official React Query Course - TanStack 中文
“如果你想*真正*理解 React Query，没有比 query.gg 更好的方法了。”—Tanner Linsley