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
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
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
在上面的示例中,您还看到可以通过使用 mutate 函数并传递 **单个变量或对象** 来为突变函数传递变量。
即使只有变量,突变本身也不是特别之处,但当与 onSuccess 选项、Query Client 的 invalidateQueries 方法以及 Query Client 的 setQueryData 方法结合使用时,突变就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,这意味着您不能直接在 **Solid 16 及更早版本** 的事件回调中使用它。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 Solid 事件池。
// This will not work in Solid 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 Solid 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>
}
有时您需要清除突变请求的 error 或 data。要做到这一点,您可以使用 reset 函数来处理。
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>
)
}
useMutation 提供了一些辅助选项,可以在突变生命周期的任何阶段快速轻松地执行副作用。这些选项对于 在突变后使查询失效并重新获取 以及 乐观更新 都很有用。
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。
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,除了 useMutation 上定义的那些之外,还需要 **触发其他回调**。这可以用于触发特定组件的副作用。要做到这一点,您可以在突变变量之后,将任何相同的回调选项传递给 mutate 函数。支持的选项包括: onSuccess、onError 和 onSettled。请注意,如果您的组件在突变完成 **之前** unmount,这些附加回调将不会运行。
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!
},
})
关于连续突变,onSuccess、onError 和 onSettled 回调的处理方式略有不同。当传递给 mutate 函数时,它们只会触发 **一次**,并且仅在组件仍然挂载时触发。这是因为每次调用 mutate 函数时,突变观察者都会被移除并重新订阅。相反,useMutation 的处理程序会为每次 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。
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
},
})
})
使用 mutateAsync 而不是 mutate 来获取一个 Promise,该 Promise 在成功时解析或在错误时抛出。例如,这可用于组合副作用。
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')
}
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。
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。
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。
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()
如果您使用 persistQueryClient 插件 来持久化离线突变,则在页面重新加载时无法恢复突变,除非您提供默认的突变函数。
这是一个技术限制。当持久化到外部存储时,只能持久化突变的状态,因为函数无法被序列化。在水合之后,触发突变的组件可能没有挂载,因此调用 resumePausedMutations 可能会产生错误:未找到 mutationFn。
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>
)
}
我们还有一个广泛的 离线示例,涵盖了查询和突变。
默认情况下,所有突变都并行运行——即使您多次调用同一个突变的 .mutate()。可以通过提供 id 来为突变指定 scope 来避免这种情况。具有相同 scope.id 的所有突变将串行运行,这意味着当它们被触发时,如果该作用域已有突变正在进行中,它们将处于 isPaused: true 状态。它们将被放入队列,并在其队列中的时间到来时自动恢复。
const mutation = useMutation(() => {
mutationFn: addTodo,
scope: {
id: 'todo',
},
})
const mutation = useMutation(() => {
mutationFn: addTodo,
scope: {
id: 'todo',
},
})
有关突变的更多信息,请参阅社区资源中的 #12: Mastering Mutations in Solid Query。