javascript - async/await 不会将构建的数组返回给父 array.map()

Question

在下面的代码中，expiringContentsAllBU填充在 async/await 函数getOnlyContentWhatsNewReport中，该函数位于 内部array.map()，但expiringContentsAllBU在函数外部访问它时变为空businessUnits.map()。

const getExpiringContents = async () => {
  let businessUnits = Object.keys(contentFulSpaces);  
  let expiringContentsAllBU = [];
  businessUnits.map( async (bu) => {
      await getOnlyContentWhatsNewReport(bu, (err, result) => { 
        if(result) {
          let expiringContentsByBU = {};
          expiringContentsByBU['businessUnit'] = bu;
          expiringContentsByBU['expiringContents'] = result;
          expiringContentsAllBU.push(JSON.parse(JSON.stringify(expiringContentsByBU)));
        } else console.log('No expiring contents found for WhatsNewSection');
      })
    });
    console.log('result', expiringContentsAllBU);
}

标签： javascriptnode.jsecmascript-6promiseasync-await

Answer 1

var getOnlyContentWhatsNewReport = Promise.resolve(123);

const getExpiringContents = async () => {
  let businessUnits = [{ id: 1 }, { id: 2 }, { id: 3 }];  
  const expiringContentsAllBU = await Promise.all(businessUnits.map(async (bu) => {
      return getOnlyContentWhatsNewReport.then(respBu => {
        bu.businessUnit = respBu;
        return bu;
      }).catch((err) => {
        console.log('No expiring contents found for WhatsNewSection');
        return null;
      });
   }));
   console.log('result', expiringContentsAllBU);
}

getExpiringContents();

您必须等到地图完成并完成所有回调。和随后的console.log代码块将在你的地图完成之前执行，所以

const getExpiringContents = async () => {
  let businessUnits = Object.keys(contentFulSpaces);  
  const expiringContentsAllBU = await Promise.all(businessUnits.map(async (bu) => {
      return getOnlyContentWhatsNewReport(bu, (err, result) => { 
        if(result) {
          let expiringContentsByBU = {};
          expiringContentsByBU['businessUnit'] = bu;
          expiringContentsByBU['expiringContents'] = result;
          return JSON.parse(JSON.stringify(expiringContentsByBU);
        } else {
          console.log('No expiring contents found for WhatsNewSection');
          return null;
        }
      })
   }));
   console.log('result', expiringContentsAllBU);
}