查询取消

查询取消

TanStack Query 为每个查询函数提供一个 AbortSignal 实例。当查询过时或变为非活动状态时，此信号将变为中止状态。这意味着所有查询都是可取消的，如果需要，您可以在查询函数内部响应取消操作。最好的部分是，这允许您继续使用正常的 async/await 语法，同时获得自动取消的所有好处。

AbortController API 在大多数运行时环境中都可用，但如果您的运行时环境不支持它，您将需要提供一个 polyfill。有几个可用的 polyfill。

默认行为

默认情况下，在 Promise 解析之前卸载或变为未使用的查询不会被取消。这意味着在 Promise 解析后，结果数据将在缓存中可用。如果您已开始接收查询，但在完成之前卸载了组件，这将非常有用。如果您再次挂载组件且查询尚未被垃圾回收，则数据将可用。

但是，如果您使用 AbortSignal，Promise 将被取消（例如，中止 fetch），因此，Query 也必须被取消。取消查询将导致其状态恢复到之前的状态。

使用 fetch

tsx

const query = useQuery({
  queryKey: ['todos'],
  queryFn: async ({ signal }) => {
    const todosResponse = await fetch('/todos', {
      // Pass the signal to one fetch
      signal,
    })
    const todos = await todosResponse.json()

    const todoDetails = todos.map(async ({ details }) => {
      const response = await fetch(details, {
        // Or pass it to several
        signal,
      })
      return response.json()
    })

    return Promise.all(todoDetails)
  },
})

const query = useQuery({
  queryKey: ['todos'],
  queryFn: async ({ signal }) => {
    const todosResponse = await fetch('/todos', {
      // Pass the signal to one fetch
      signal,
    })
    const todos = await todosResponse.json()

    const todoDetails = todos.map(async ({ details }) => {
      const response = await fetch(details, {
        // Or pass it to several
        signal,
      })
      return response.json()
    })

    return Promise.all(todoDetails)
  },
})

使用 axios v0.22.0+

tsx

import axios from 'axios'

const query = useQuery({
  queryKey: ['todos'],
  queryFn: ({ signal }) =>
    axios.get('/todos', {
      // Pass the signal to `axios`
      signal,
    }),
})

import axios from 'axios'

const query = useQuery({
  queryKey: ['todos'],
  queryFn: ({ signal }) =>
    axios.get('/todos', {
      // Pass the signal to `axios`
      signal,
    }),
})

使用 axios with version lower than v0.22.0

tsx

import axios from 'axios'

const query = useQuery({
  queryKey: ['todos'],
  queryFn: ({ signal }) => {
    // Create a new CancelToken source for this request
    const CancelToken = axios.CancelToken
    const source = CancelToken.source()

    const promise = axios.get('/todos', {
      // Pass the source token to your request
      cancelToken: source.token,
    })

    // Cancel the request if TanStack Query signals to abort
    signal?.addEventListener('abort', () => {
      source.cancel('Query was cancelled by TanStack Query')
    })

    return promise
  },
})

import axios from 'axios'

const query = useQuery({
  queryKey: ['todos'],
  queryFn: ({ signal }) => {
    // Create a new CancelToken source for this request
    const CancelToken = axios.CancelToken
    const source = CancelToken.source()

    const promise = axios.get('/todos', {
      // Pass the source token to your request
      cancelToken: source.token,
    })

    // Cancel the request if TanStack Query signals to abort
    signal?.addEventListener('abort', () => {
      source.cancel('Query was cancelled by TanStack Query')
    })

    return promise
  },
})

使用 XMLHttpRequest

tsx

const query = useQuery({
  queryKey: ['todos'],
  queryFn: ({ signal }) => {
    return new Promise((resolve, reject) => {
      var oReq = new XMLHttpRequest()
      oReq.addEventListener('load', () => {
        resolve(JSON.parse(oReq.responseText))
      })
      signal?.addEventListener('abort', () => {
        oReq.abort()
        reject()
      })
      oReq.open('GET', '/todos')
      oReq.send()
    })
  },
})

const query = useQuery({
  queryKey: ['todos'],
  queryFn: ({ signal }) => {
    return new Promise((resolve, reject) => {
      var oReq = new XMLHttpRequest()
      oReq.addEventListener('load', () => {
        resolve(JSON.parse(oReq.responseText))
      })
      signal?.addEventListener('abort', () => {
        oReq.abort()
        reject()
      })
      oReq.open('GET', '/todos')
      oReq.send()
    })
  },
})

使用 graphql-request

可以在客户端 request 方法中设置 AbortSignal。

tsx

const client = new GraphQLClient(endpoint)

const query = useQuery({
  queryKey: ['todos'],
  queryFn: ({ signal }) => {
    client.request({ document: query, signal })
  },
})

const client = new GraphQLClient(endpoint)

const query = useQuery({
  queryKey: ['todos'],
  queryFn: ({ signal }) => {
    client.request({ document: query, signal })
  },
})

使用 graphql-request with version lower than v4.0.0

可以在 GraphQLClient 构造函数中设置 AbortSignal。

tsx

const query = useQuery({
  queryKey: ['todos'],
  queryFn: ({ signal }) => {
    const client = new GraphQLClient(endpoint, {
      signal,
    })
    return client.request(query, variables)
  },
})

const query = useQuery({
  queryKey: ['todos'],
  queryFn: ({ signal }) => {
    const client = new GraphQLClient(endpoint, {
      signal,
    })
    return client.request(query, variables)
  },
})

手动取消

您可能想要手动取消查询。例如，如果请求需要很长时间才能完成，您可以允许用户单击取消按钮来停止请求。为此，您只需调用 queryClient.cancelQueries({ queryKey })，这将取消查询并将其恢复到之前的状态。如果您使用了传递给查询函数的 signal，TanStack Query 还会额外取消 Promise。

tsx

const query = useQuery({
  queryKey: ['todos'],
  queryFn: async ({ signal }) => {
    const resp = await fetch('/todos', { signal })
    return resp.json()
  },
})

const queryClient = useQueryClient()

return (
  <button
    onClick={(e) => {
      e.preventDefault()
      queryClient.cancelQueries({ queryKey: ['todos'] })
    }}
  >
    Cancel
  </button>
)

const query = useQuery({
  queryKey: ['todos'],
  queryFn: async ({ signal }) => {
    const resp = await fetch('/todos', { signal })
    return resp.json()
  },
})

const queryClient = useQueryClient()

return (
  <button
    onClick={(e) => {
      e.preventDefault()
      queryClient.cancelQueries({ queryKey: ['todos'] })
    }}
  >
    Cancel
  </button>
)

局限性

当使用 Suspense hooks 时，取消操作不起作用：useSuspenseQuery、useSuspenseQueries 和 useSuspenseInfiniteQuery。