javascript - Node.js Q promise 多个参数

Question

尝试在我的 nodejs express 应用程序中使用 Q promise 库清理我的回调意大利面条代码，但我在翻译它的某些部分时遇到了问题。无法将多个参数传递给函数并处理范围。

这是一个简化的“同步”版本来展示我的逻辑:

function updateFacebook(req, res) {
    var user = getUserFromDB(userid);
    var profile = getUserProfileFromAPI(accessToken);

    var success = updateUserDB(user, profile);
    res.json({ result: success });
}

所以我将回调函数转换为返回 promise

function getUserFromDB(userid) {
    var deferred = Q.defer();
    // somewhere in here there's a deferred.resolve(user object);
    queryMongo()...
    return deferred.promise;
}

function getUserProfileFromAPI(accessToken) {
    var deferred = Q.defer();
    // somewhere in here there's a deferred.resolve(profile object);
    request()...
    return deferred.promise;
}

function updateUserDB(user, profile) {
    var deferred = Q.defer();
    // somewhere in here there's a deferred.resolve(updated user object);
    updateMongo()...
    return deferred.promise;
}

function handleResponse(res, user) {
    var deferred = Q.defer();

    // was thinking about putting the res.json here
    // i have no way of passing in the res
    // and res is out of scope...
    res.json({});

    return deferred.promise;
}

现在的问题是把它们联系起来，我试过了......

Q.when(getUserFromDB(userid), getUserProfileFromAPI(accessToken))
 .spread(updateUserDB)
 .done(handleResponse);

Q.all([getUserFromDB(userid), getUserProfileFromAPI(accessToken)])
 .spread(updateUserDB)
 .done(handleResponse);

super 困惑。任何方向将不胜感激。

Answer 1

看起来您的 handleResponse 需要两个参数，但是 updateUserDB 只解析一个对象。你可以这样做:

function getResponseHandler(res) {
    return function(user) {
        // your handleResponse code here
        // which now has access to res
    }
}

然后像这样调用它:

Q.all([getUserFromDB(userid), getUserProfileFromAPI(accessToken)])
 .spread(updateUserDB)
 .done(getResponseHandler(res));