Bluebird Promise.map無法正常工作

Question

我試圖在問題和答案之間建立關聯。我正在使用Bluebird的API .map來確保僅在所有question.addAnswers(answer)承諾完成後發生重定向。因此，在我的終端，我看到這樣的事情：

done adding a answer to the question 
done adding a answer to the question 
finished 

不過，我看到的是：

finished 
done adding a answer to the question 
done adding a answer to the question 

因此，我假設Promise.map是不工作的。我錯過了什麼？我怎樣才能使它工作？

這裏是我的代碼：

router.post('/create', function(req, res) { 
    models.Question.create({ 
    content: req.body.question 
    }) 
    .then(function(question) { 
    if (!question) { 
     res.render('questions/new', { 
      error: "Question \"#{req.body.question}\" fails to be created" 
     }); 
    } else { 
     // Update the new question to each user 
     models.User.findAll() 
     .then(function(users) { 
     users.forEach(function(user) { 
      user.addQuestion(question) 
     }); 
     }); 
     Promise.map(req.body.answers, function(answer){ 
     return createAndAddToQuestion(question, answer, res) 
     }) 
     .then(function(){ 
     console.log('finished') 
     res.redirect("https://stackoverflow.com/questions/success/?question_id=" + question.id); 
     }); 
    }; 
    }) 
}) 

var createAndAddToQuestion = function(question, answer, res) { 
    models.Answer.create({ 
    content: answer 
    }) 
    .then(function(ans) { 
    if (ans) { 
     var promise = question.addAnswer(ans) 
     promise.then(function(){ 
     console.log("done adding a answer to the question") 
     }); 
     return question.addAnswer(ans); 
    } else { 
     res.render('questions/new', { 
     error: "Answer \"#{answer}\" fails to be created" 
     }); 
    }; 
    }); 
} 

UPDATE 我剛剛更新createAndAddToQuestion，所以它會返回一個承諾來代替。結果保持不變。 Promise.map不起作用。

var createAndAddToQuestion = function(question, answer, res) { 
    models.Answer.create({ 
    content: answer 
    }) 
    .then(function(ans) { 
    if (ans) { 
     return question.addAnswer(ans).then(function() { 
     console.log('done') 
     }) 
    } else { 
     res.render('questions/new', { 
     error: "Answer \"#{answer}\" fails to be created" 
     }); 
    }; 
    }); 
} 

Answer 1

你最突出的問題是，createAndAddToQuestion不返回一個承諾，所以map不知道等待什麼。

此外，您不等models.User.findAll，調用question.addAnswer(ans);兩次，可能會嘗試多次呈現錯誤消息，如果答案未能創建，並且沒有通用錯誤處理程序。你應該做的

router.post('/create', function(req, res) { 
    createQuestion(req.body).then(function(question) { 
    console.log('finished') 
    res.redirect("https://stackoverflow.com/questions/success/?question_id=" + question.id); 
    }, function(err) { 
    res.render('questions/new', { 
     error: err.message 
    }); 
    }).catch(function(err) { 
    console.error(err); 
    res.status(500); 
    }); 
}); 

function createQuestion(opts) { 
    return models.Question.create({ 
    content: opts.question 
    }) 
    .then(function(question) { 
    if (!question) { 
     throw new Error("Question \"#{opts.question}\" fails to be created"); 
    } 
    // Update the new question to each user 
    return Promise.all([ 
     models.User.findAll() 
     .then(function(users) { 
     users.forEach(function(user) { 
      user.addQuestion(question) 
     }) 
     }), 
     Promise.map(opts.answers, function(answer){ 
     return createAndAddToQuestion(question, answer) 
     }) 
    ]).return(question); 
    }); 
} 

function createAndAddToQuestion(question, answer) { 
    return models.Answer.create({ 
    content: answer 
    }) 
    .then(function(ans) { 
    if (!ans) { 
     throw new Error("Answer \"#{answer}\" fails to be created"); 
    } 
    return question.addAnswer(ans); 
    }) 
    .then(function(){ 
    console.log("done adding a answer to the question") 
    }); 
}