javascript - 在 Lambda 中的 node8.10 中获取 API 调用导致 Promise和未定义

Question

我有一个用 Node8.1 编写的 Lambda 函数，我试图在其中获取一组对象（来自 Unsplash API 的服务器照片），然后将它们写入 DynamoDB。现在我无法得到我的 API 调用的结果，尽管链接承诺。任何帮助将不胜感激。

我已经尝试在我的函数中链接承诺以及异步/等待，但不断收到以下错误：

Promise {
  <pending>,
...

和

TypeError: Cannot read property 'results' of undefined
    at unsplash.search.photos.then.then.photos (/Users/stackery/Code/dynamodb-to-ses/src/writeToTable/index.js:19:12)
    at process._tickCallback (internal/process/next_tick.js:68:7)

这是我的功能：

function getPhotos () {
  // get items from the unsplash api
  return unsplash.search.photos('servers')
  .then( photos => {
    toJson(photos)
  })
  .then( photos => {
    // filter out restaurant servers - that's not what we're going for
    photos.results.filter( photo => {
      return photo.description.includes('computer') || photo.alt_description.includes('computer') || photo.description.includes('data') || photo.alt_description.includes('data');
    }).then( photos => {
      return photos;
    });
  }).catch ( error => {
    console.log('Error getting photos');
    console.log(error);
  });
}

exports.handler = async () => {
  const results = await getPhotos();

  (other function logic)

  const response = {
    statusCode: 200,
    headers: {
      'Content-Type': 'application/json'
    },
    body: JSON.stringify(results)
  };

  return response;
};

我期望来自 Unsplash API 的一组对象（我的凭据未显示，但它们是正确的，我可以访问 API）。

* *****编辑：***** *

这是我的相同功能的版本，带有 async/await （我更喜欢使用）：

async function getPhotos () {
  // get items from the unsplash api
  try {
    const photos = await unsplash.search.photos('servers', 1, 500); // get all 300+ photos
    const json = await toJson(photos);
    console.log(json); // this is working now, but filtering is not
    const serverPhotos = json;
    // filter out restaurant servers - that's not what we're going for
    return serverPhotos.results.filter(photo => {
      return photo.description.toLowerCase().includes('computer') || photo.alt_description.toLowerCase().includes('computer') || photo.description.toLowerCase().includes('data') || photo.alt_description.toLowerCase().includes('data') || photo.description.toLowerCase().includes('network');
    });
  }
  catch (error) {
    console.log('Error getting photos');
    console.log(error);
  }
}

exports.handler = async () => {
  const results = await getPhotos();
  ...
  return response;
};

它也不起作用，并且失败并出现以下错误：

Error getting photos
TypeError: Cannot read property 'filter' of undefined
    at getPhotos (/Users/stackery/Code/dynamodb-to-ses/src/writeToTable/index.js:18:18)
    at process._tickCallback (internal/process/next_tick.js:68:7)

这就是我所期待的——一组像这样的对象：

     [{ id: '6vA8GCbbtL0',
       created_at: '2019-03-14T13:39:20-04:00',
       updated_at: '2019-03-19T15:01:00-04:00',
       width: 3422,
       height: 4278,
       color: '#F8F7F7',
       description: 'Computer interior',
       alt_description: 'black and white computer tower',
       urls: [Object],
       links: [Object],
       categories: [],
       sponsored: false,
       sponsored_by: null,
       sponsored_impressions_id: null,
       likes: 35,
       liked_by_user: false,
       current_user_collections: [],
       user: [Object],
       tags: [Array],
       photo_tags: [Array] },
     ...
     ]

标签： javascriptnode.jslambdaasync-awaites6-promise

Answer 1

这部分函数链不会返回Promise对象，因为没有return：

  .then( photos => {
    toJson(photos)
  })

尝试将其更改为

  .then( photos => {
    return toJson(photos)
  })

或者即使.then(toJson)你感到雄心勃勃（：

否则，photos.results不定义