NodeJs amazon-cognito identity-js signUp成功但不返回结果

Question

我已经从npm导入了node-fetch amazon-cognito-identitiy-js，并且正在尝试部署一个自定义的注册lambda函数。

global.fetch = require('node-fetch');
const AmazonCognitoIdentity = require('amazon-cognito-identity-js');

const poolData = {
  UserPoolId: "ap-southeast-1_******",
  ClientId: "***********"
}

module.exports.router = (event, context, callback) => {
  return createUser(event, context, callback);
};

function createUser(event, context, callback) {

  let postBody = JSON.parse(event.body);

  /*cognito test*/
  const userPool = new AmazonCognitoIdentity.CognitoUserPool(poolData);
  var attributeList = [];
  attributeList.push(new AmazonCognitoIdentity.CognitoUserAttribute({Name:"email",Value:postBody.email}));

  var cognitoResult = null;

  userPool.signUp(postBody.email, 'ke$2kelmDj123', attributeList, null, function(err, result){
      if (err) {
        cognitoResult = err;
      } else {
        cognitoResult = result;
      }
  });

  const response = {
    statusCode: 201,
    headers: {
      "Access-Control-Allow-Origin" : "*",
      "Access-Control-Allow-Credentials" : true
    },
    body: JSON.stringify({ message: "register account", special: postBody["name"], cognito: cognitoResult })
  };

  callback(null, response);
}

由于某些原因，即使用户是在我的用户池中创建的，cognitoResult也只会返回null。

Answer 1

这是因为这段代码

userPool.signUp(postBody.email, 'ke$2kelmDj123', attributeList, null, function(err, result){
      if (err) {
        cognitoResult = err;
      } else {
        cognitoResult = result;
      }
  });

是异步的，并且您不需要等待结果。您只需在此问题尚未解决时返回响应即可。它最终会解析(您可以通过正在创建的用户观察到)，但此时您已经从Lambda函数返回。

您可以通过在else块中嵌入响应来解决此问题。

userPool.signUp(postBody.email, 'ke$2kelmDj123', attributeList, null, function(err, result){
      if (err) {
        cognitoResult = err;
        // place error response here
      } else {
        cognitoResult = result;

        const response = {
          statusCode: 201,
          headers: {
            "Access-Control-Allow-Origin" : "*",
            "Access-Control-Allow-Credentials" : true
          },
          body: JSON.stringify({ message: "register account", special: postBody["name"], cognito: cognitoResult })
        };

        callback(null, response);
      }
  });

请注意，您还应该创建一个错误响应。