当服务器关闭时 React-Apollo 捕获答案

【问题标题】：React-Apollo catch when server is down当服务器关闭时 React-Apollo 捕获
【发布时间】：2020-09-14 23:01:48
【问题描述】：

在我的带有节点服务器的 React ApolloGraphQL 应用程序中，我试图让它在我的节点服务器关闭时捕获错误。当节点服务器启动时，一切正常且正常... graphQL 错误被捕获并显示。但是当我停止节点服务器时，我会遇到无法避免的运行时错误。当节点服务器关闭时，服务器会以 503 Service Unavailable 响应和非 JSON 的 html 页面进行响应。

apollo 客户端是这样设置的：

const client = new ApolloClient({
  assumeImmutableResults: true,
  fetchOptions: {
    credentials: "include"
  },
  fetch: fetch,
  onError: ({ graphQLErrors, networkError }) => {
    if (graphQLErrors)
      graphQLErrors.map(({ message, locations, path }) =>
        console.log(`[GraphQL error]: Message: ${message}, Location: ${locations}, Path: ${path}`,),);
    if (networkError) {console.log(`[Network error]: ${networkError}`);}
    response = {errors:null};
  },
  cache: new InMemoryCache({
    freezeResults: true,
    dataIdFromObject: obj => {
      let dataId = null;
      switch (obj.__typename) {
        default:
          dataId = defaultDataIdFromObject(obj);
      }
      return dataId;
    },
    cacheRedirects: {
      Query: {
        productVariant: (_, args, { getCacheKey }) => {
          const cacheKey = getCacheKey({ __typename: "ProductVariant", ...args });
          return cacheKey;
        }
      }
    },
  }),
});

上面的onError 阻止响应此消息：

Error: Network error: JSON.parse: unexpected character at line 1 column 1 of the JSON data

我以这种方式设置了突变：

const [mutateVariant, {data, error, loading}] = useMutation(UPDATE_PRODUCT_META);

我这样称呼它：

mutateVariant({ variables: {inputM: {...buildMetaInput(editedData)} }, 
    errorPolicy: 'ignore', onError: (error) => Logger("Error:", error)});

您可以看到我已经尝试了不同的errorPolicy 设置并添加了onError 回调。

但我不断收到未处理的运行时错误，似乎无法捕捉和处理它们：

Unhandled Runtime Error

Error: Network error: JSON.parse: unexpected character at line 1 column 1 of the JSON data
Call Stack
ApolloError           webpack-internal:///./node_modules/apollo-client/bundle.esm.js (76:28)
error                 webpack-internal:///./node_modules/apollo-client/bundle.esm.js (1041:48)
notifySubscription    webpack-internal:///./node_modules/zen-observable/lib/Observable.js (140:18)
onNotify              webpack-internal:///./node_modules/zen-observable/lib/Observable.js (179:21)
error                 webpack-internal:///./node_modules/zen-observable/lib/Observable.js (240:15)
error/<               webpack-internal:///./node_modules/apollo-client/bundle.esm.js (880:76)
error                 webpack-internal:///./node_modules/apollo-client/bundle.esm.js (880:27)
notifySubscription    webpack-internal:///./node_modules/zen-observable/lib/Observable.js (140:18)
onNotify              webpack-internal:///./node_modules/zen-observable/lib/Observable.js (179:21)
error                 webpack-internal:///./node_modules/zen-observable/lib/Observable.js (240:15)
error                 webpack-internal:///./node_modules/apollo-link-error/lib/bundle.esm.js (53:34)
notifySubscription    webpack-internal:///./node_modules/zen-observable/lib/Observable.js (140:18)
onNotify              webpack-internal:///./node_modules/zen-observable/lib/Observable.js (179:21)
error                 webpack-internal:///./node_modules/zen-observable/lib/Observable.js (240:15)
createHttpLink/</</<  webpack-internal:///./node_modules/apollo-link-http/lib/bundle.esm.js (92:26)

useMutation 钩子返回的error 数据：

graphQLErrors: Array []
message: "Network error: JSON.parse: unexpected character at line 1 column 1 of the JSON data"
networkError: {…}
  bodyText: "<!DOCTYPE HTML PUBLIC \"-//IETF//DTD HTML 2.0//EN\">\n<html><head>\n<title>503 Service 
  Unavailable</title>\n</head><body>\n<h1>Service Unavailable</h1>\n<p>The server is temporarily unable 
  to service your\nrequest due to maintenance downtime or capacity\nproblems. Please try again later.  
  </p>\n<p>Additionally, a 503 Service Unavailable\nerror was encountered while trying to use an 
  ErrorDocument to handle the request.</p>\n</body></html>\n"
  name: "ServerParseError"
  response: Object {  }
  statusCode: 503

如何发现这个错误？

【问题讨论】：

我不确定这是否有意义（完全），但如果你没有找到更好的解决方案，你可以包装你传递给新的 ApolloClient 的 fetch 函数（例如const newFetch = (url, options) => {/* ... */}） .在您的包装器中，您可以检查您的错误并在这种情况下返回模拟的模拟响应????‍♀️。我会寻找比这更聪明的解决方案，尽管哈哈

标签： reactjs react-hooks react-apollo apollo-client

【解决方案1】：

mutateVariant 函数返回一个承诺。尝试在调用后添加一个 .catch()。

mutateVariant().catch(() => {...});

【讨论】：