呈现两个单独的async.each方法的结果

Question

我是nodejs和async的新手。无法理解如何包装两个单独的async.each方法以具有一个res.render ...我试图在前端显示有效帐户ID和有效用户ID的列表。两个单独的async.each方法是：

async.each(account_ids, function(accountId, callback) {
        console.log('Processing accountId ' + accountId);

        callingExternalApi(accountId, callback, function(err, response){
          if(err){
            console.log("error account");
          }
          console.log("account response is: ", response);
        });

      }, function(err) {
        if( err ) {
          console.log('An account failed to process');
        } else {
          console.log('All accounts have been processed successfully');
        }
      });

和

async.each(email_ids, function(emailId, callback) {
        console.log('Processing email id ' + emailId);
        request({
          url: emailIdlookupUrl,
          method: 'POST',
          json: {
            email_address: emailId
          }
        }, function (err, response, body) {
          if (err) {
            logger.error(err);
            req.flash('error', err.message);
            return res.redirect('?');
          }
          if (response.statusCode !== 200) {
            const msg = 'Unable to verify user';
            req.flash('error', msg);
            return res.redirect('?');
          }
          console.log("user id is: ", body.user.id);
          callback();
        });

      }, function(err) {
        if( err ) {
          console.log('An email failed to process');
        } else {
          console.log('All user emails have been processed successfully');
        }
      });

非常感谢您的帮助。请原谅任何多余的回调或错误记录。仍在学习nodejs。

谢谢！

Answer 1

主要问题不是您同时调用了这两个async.each调用。问题在于它们将并行运行，而调用req。*函数或回调函数的最快的函数将返回对连接的响应。

如果忽略了它们的回调参数，这两个函数都将返回promise。

我建议一般同时阅读异步库和JS async / await：

• https://javascript.info/async-await
• https://caolan.github.io/async/v3/docs.html#each
• https://zellwk.com/blog/async-await-express/

请注意，异步还接受本机异步功能，许多查找程序使这些功能更加简洁易懂。

这是我想从上面的代码中得到的，包括将结果编译成列表：

var request = require("request-promise");

async function checkAccounts(account_ids) {
  const valid_accounts = [];
  await async.each(account_ids, async function(accountId) {
    console.log("Processing accountId " + accountId);
    const extAPIresult = await callingExternalApi(accountId);
    console.log("account response is: ", extAPIresult);
  });
  valid_accounts.push(extAPIresult);
  console.log("All accounts have been processed successfully");
  return valid_accounts;
}

async function checkEmails(email_ids) {
  const valid_emails = [];
  await async.each(email_ids, async function(emailId) {
    console.log("Processing email id " + emailId);
    const reqresult = await request({
      url: emailIdlookupUrl,
      method: "POST",
      json: {
        email_address: emailId
      }
    });
    if (reqresult.statusCode !== 200) {
      throw new Error("Unable to verify user");
    }
    valid_emails.push(reqresult.body.user.id);
    console.log("user id is: ", reqresult.body.user.id);
  });
  console.log("All emails have been processed successfully");
  return valid_emails;
}

async function doChecks() {
  const accounts = checkAccounts(account_ids);
  const emails = checkEmails(email_ids);
  const responses = await Promises.all([accounts, emails]);
  console.log("All checks have been proccessed successfully");
  return responses;
}

function get(req, res) {
  doChecks()
    .then(responses => {
      res.send("All checks have been proccessed successfully");
      res.send(String(responses));
    })
    .catch(err => {
      req.flash("error", err.message);
      res.redirect("?");
    });
}