在猫鼬中使用Promise的最佳实践

Question

I'm quite new with this promise concept. I'm not sure but looking at this, I belieave I'm just using promise as callbacks and I'm ending in a promise hell!

I've this function which is suppose to get user object from MongoUser database, update it and save it again. here's my code snippet:

var changePassword = function(data){
      return new Promise(function(fulfill, reject){
        MongoUser.findOne({username: data.username}).exec()
          .then(function(mongoUser){
            //mongoUser = new MongoUser();
            //mongoUser.username = data.username;
            mongoUser.password = data.password;
            mongoUser.save().then(function(){
              fulfill(data);
            }).catch(function(error){
              log.error("MongoDB Failed in updating data", {"error": error});
              reject(error);
            });
          })
          .catch(function(error){
            log.error("MongoDB Failed in updating data", {"error": error});
            reject(error);
          });
      });
};

Any Idea how to use returned promise from Mongoose without creating a new one?

Answer 1

Mongoose supports promises already, so I think that you can rewrite your code to this:

var changePassword = function(data) {
  return MongoUser.findOne({username: data.username}).then(function(mongoUser) {
    mongoUser = new MongoUser();
    mongoUser.username = data.username;
    mongoUser.password = data.password;
    return mongoUser.save();
  }).catch(function(error){
    log.error("MongoDB Failed in updating data", {"error": error});
    throw error;
  });
};

(although I'm not sure why you are creating a user that may already exists).

Answer 2

Rightly Said: Mongoose supports promises already. Also, I don't think so you need to create a new user with new credential instead you need to change password of current user. Also I have returned the data while calling "changePassword" function.

var changePassword = function(data){
  return MongoUser.findOne({username: data.username}).exec()
      .then(function(mongoUser){
        mongoUser.username = data.username;
        mongoUser.password = data.password;
         return mongoUser.save();
      })
     .then(function(newSavedData) {
                return newSavedData; // returns the new saved data
      })
     .catch(function(error){
          log.error("MongoDB Failed in updating data", {"error": error});
          reject(error);
      });
};