javascript - 链式承诺 - 返回的承诺解析不会导致调用 then 方法

Question

我正在尝试链接承诺，但由于某种原因，我的 then 方法没有被调用 - 找不到原因，非常感谢您的帮助。then - .then((decodedTokenData) 没有被调用，而是返回了整个承诺。

let handler = async (event) => {
let accessToken = undefined;
let targetGroup = undefined;
const promise = new Promise(() => {
    accessToken = event.header.authorization;
    targetGroup = event.body.targetGroup;

    let promise = decodeAndVerifyToken(accessToken);
    return promise;
}).then((decodedTokenData) => {
    let isNotGroupMemberResult = isNotGroupMember(decodedTokenData.userGroups);
    return setUserGroup(result.userGroups, targetGroup, userPoolId);
}).then(() => {
    return true;
});
return promise;
}


let decodeAndVerifyToken = (jwtToken) => {
return new Promise((resolve, reject) => {
    jwt.verify(jwtToken, pem, function (err, dToken) {
        if (err) {
            reject(err);
        }

        let userGroups = dToken && dToken["cognito:groups"] ? dToken["cognito:groups"] : [];
        let username = dToken && dToken.username ? dToken.username : null;

        let retval = {
            userGroups,
            username,
            decodedToken: dToken
        }
        resolve(retval);
    })
});
}

let isNotGroupMember = (userGroups) => {
let groupIndex = userGroups.findIndex(groupName => groupName.include(reviewersGroup) || groupName.include(ownersGroup));
let isNotGroupMemberRetval = groupIndex == -1;
return isNotGroupMemberRetval;
}

let setUserGroup = (username, groupname, userPoolId) => {
return new Prmoise((resove, reject) => {
    var params = {
        GroupName: groupname,
        UserPoolId: userPoolId,
        Username: username
    };

    cognitoidentityserviceprovider.adminAddUserToGroup(params, function (err, data) {
        if (err) {
            reject(err);
        } else
            resolve(data);
    });
});
};

编辑：我理解我的问题......我阅读了有关 Mozilla 承诺的以下文档：一旦承诺被履行或拒绝，相应的处理程序函数（onFulfilled 或 onRejected）将被异步调用（在当前线程循环中调度）。处理函数的行为遵循一组特定的规则。如果处理函数：

returns a value, the promise returned by then gets resolved with the returned value as its value.

而且我认为它适用于承诺和 then 方法 - 但它仅适用于 then 方法......

标签： javascriptecmascript-6es6-promise

Answer 1

new Promise传递resolve并传递reject给回调，但您没有在这里使用它：

const promise = new Promise(() => {
    accessToken = event.header.authorization;
    targetGroup = event.body.targetGroup;

    let promise = decodeAndVerifyToken(accessToken);
    return promise;
})

这会创建一个永远不会解决的承诺。这里没有必要new Promise。直接调用decodeAndVerifyToken即可：

decodeAndVerifyToken(event.header.authorization)
  .then((decodedTokenData) => { ... })
  ...