nodejs async/await 嵌套 API 进度

Question

我有一个 API 用于搜索用户提供的术语，returns 一组结果，然后针对每个结果触发异步请求并获取其中每一秒的结果一批请求。我希望 API 报告进度，而不仅仅是最终结果。所以，如果我执行以下请求，我应该得到这样的更新

$ curl 'http://server/?q=foobar'
searching for ${q}…
found 76… now getting images…
found 30 images… done
{
    result
}

大部分相关代码如下所示。首先，我正在为我的应用程序使用 hapijs。

let imagesOfRecords = {};

const getImages = async function (q) {

    console.log(`searching for ${q}…`);
    const uri = `http://remoteserver/?q=${q}`;
    const {res, payload} =  await Wreck.get(uri);
    const result = JSON.parse(payload.toString()).hits;
    const numOfFoundRecords = result.total;

    if (result.total) {

        console.log(`found ${result.total}… now getting images…`);
        const foundRecords = result.hits.map(getBuckets);
        Promise.all(foundRecords).then(function() {

            console.log(`found ${Object.keys(imagesOfRecords).length} images… done`);
            reply(imagesOfRecords).headers = res.headers;
        }).catch(error => { 
            console.log(error)
        });
    }
    else {
        console.log('nothing found');
        reply(0).headers = res.headers;
    }
};

const getBuckets = async function(record) {

    const { res, payload } = await Wreck.get(record.links.self);
    const bucket = JSON.parse(payload.toString()).links.bucket;
    await getImageFiles(bucket, record.links.self);
};

const getImageFiles = async function(uri, record) {

    const { res, payload } = await Wreck.get(uri);
    const contents = JSON.parse(payload.toString()).contents;
    imagesOfRecords[record] = contents.map(function(el) {
        return el.links.self; 
    });
};

一旦我可以实现它，我的下一个任务就是在使用上述 API.

的 Web 应用程序中实现这个渐进式更新

Answer 1

要显示后端请求的每个步骤的结果，您可以使用 EventEmitter，它将在每个进度步骤上发出事件。您可以阅读有关事件 here.
简单实现：

const events = require('events');
const eventEmitter = new events.EventEmitter();

//your request code
Promise.all(foundRecords).then(function() {
  console.log(`found ${Object.keys(imagesOfRecords).length} images… done`);
  eventEmitter.emit('progress');
  reply(imagesOfRecords).headers = res.headers;
})

const eventReaction = (e) => {
  // do something with event, console log for example.
}
eventEmitter.on('progress', eventReaction);

您可以找到更多示例 here and here。
要向客户端显示事件，您可以使用库 socket.io. I think you can find pretty straightforward explanations how socket.io works in documentation.
如果你想在服务器或进程之间发送事件并且想走得更远，你可以阅读更多关于 0MQ（零 mq）和它的节点 implementation

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hapijs