Hapi.js UnhandledPromiseRejectionWarning：错误：回复接口调用了两次？答案

【问题标题】：Hapi.js UnhandledPromiseRejectionWarning: Error: reply interface called twice?Hapi.js UnhandledPromiseRejectionWarning：错误：回复接口调用了两次？
【发布时间】：2018-05-21 23:08:27
【问题描述】：

当我运行我的项目时，我得到了错误：

(node:5795) UnhandledPromiseRejectionWarning: Error: reply interface called twice
    at Object.exports.assert (/Users/labikemmy/Downloads/React-Native-FriendChat/api/node_modules/hoek/lib/index.js:736:11)
    at Function.internals.response (/Users/labikemmy/Downloads/React-Native-FriendChat/api/node_modules/hapi/lib/reply.js:164:10)
    at bound (domain.js:301:14)
    at Function.runBound (domain.js:314:12)
    at reply (/Users/labikemmy/Downloads/React-Native-FriendChat/api/node_modules/hapi/lib/reply.js:72:22)
    at bound (domain.js:301:14)
    at runBound (domain.js:314:12)
    at result.then (/Users/labikemmy/Downloads/React-Native-FriendChat/api/node_modules/hapi/lib/handler.js:105:36)
    at <anonymous>
    at process._tickDomainCallback (internal/process/next_tick.js:228:7)
(node:5795) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)
(node:5795) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
null

我不知道这是错误还是我的代码错误？我是屏幕 hapi.js 问题，有人说错误是错误，另一个说'reply() times is limit in the same request'？如果是有限的，如何更改下面的代码？

```

export default async function (request, reply) {
    if (request.auth.credentials.email !== request.payload.email) {
        await User.findOne({ email: request.auth.credentials.email }).then(
            (user) => {
                if (user) {
                    User.findOne({ email: request.payload.email }).then(
                        (friend) => {
                            if (friend) {
                                const stringId = `${friend._id}`;
                                const friendExists = user.friends.filter(f => `${f}` === stringId).length > 0;
                                if (!friendExists) {
                                    user.friends.push(friend);
                                    user.save();
                                    reply({ friend: { fullName: friend.fullName, _id: friend._id } });
                                } else {
                                    reply(Boom.conflict('You have added already this friend'));
                                }
                             } else {
                                 reply(Boom.notFound(`Friend ${request.payload.email} doesn't exist`));
                             }
                        },
                   );
              } else {
                   reply(Boom.notFound('Cannot find user'));
              }
         },
     );
  } else {
      reply(Boom.conflict('Cannot add yourself as a friend'));
  }
}

Hapi@16.4.1

【问题讨论】：

与您的查询无关：您的代码需要一些清理，因为它不必要地复杂。示例：await promise.then 是模棱两可的。 const 变量 = await.promise 或 promise.then(variable=>{ ... })。为了展平嵌套的 if 并提高可读性，您可以使用带条件的 switch(true) 或仅使用查找错误并抛出的单数 if。此外，如果您从处理程序中抛出错误，则 hapi 将自动回复它，因此不要在整个过程中使用回复，而是尝试使用 throw Boom.notFound(...)。这是一个示例：jsfiddle.net/hoaobrook/qd43txzp

标签： javascript hapijs

【解决方案1】：

你有任何其他插件或生命周期钩子，比如 onPreHandler 之类的吗？也许您的代码在某些时候会引发此错误，因为您（或您的代码）在实际响应之前调用了回复接口。

另外，我重构了您的代码。你已经在使用 JavaScript 异步接口，所以你不需要在你的 Promise 中添加“then”调用。

试试这个，看看会发生什么：

export default async function (request, reply) {

    if (request.auth.credentials.email === request.payload.email) {
        return reply(Boom.conflict('Cannot add yourself as a friend'))
    }

    // I belive this is mongoose model
    const user = await User.findOne({email: request.auth.credentials.email}).exec();
    if (!user) {
        return reply(Boom.notFound('Cannot find user'));
    }

    const friend = await User.findOne({email: request.payload.email}).exec();

    if (!friend) {
        return reply(Boom.notFound(`Friend ${request.payload.email} doesn't exist`));
    }

    const stringId = `${friend._id}`;
    const friendExists = user.friends.filter(f => `${f}` === stringId).length > 0;
    if (!friendExists) {
        // hmmm shouldn't it be friend._id? user.friends.push(friend._id.toString());
        user.friends.push(friend);
        // better use this statement
        // ref: http://mongoosejs.com/docs/api.html#document_Document-markModified
        user.markModified('friends');
        await user.save();
        return reply({friend: {fullName: friend.fullName, _id: friend._id}});
    } else {
        return reply(Boom.conflict('You have added already this friend'));
    }
}

【讨论】：