我试图建立一个允许随机玩家玩游戏的游戏。下面的代码应该为两个配对的玩家创建一个GameMessage对象。为了将这两个对象作为同一游戏的一部分进行关联，我决定保存为＃34; firstplayer＆＃34;制作的游戏的objectId。在现场＆＃34;其他人＆＃34; for＆＃34; secondplayer＆＃34;反之亦然。出于某种原因（也许第一个玩家和第二个玩家的第一次保存在代码尝试检索objectIds之前没有完成，这意味着没有objectIds可以获得？）。
简短版本：为什么＆＃34;其他人＆＃34;价值不节约？
Parse.Cloud.define("findpartner", function(request, response) {
var User = Parse.Object.extend("_User");
var user = new User();
var currentuser = Parse.User.current();
currentuser.set("searching", 0);
var query = new Parse.Query(User);
query.equalTo("searching", 1);
query.limit(50); //limit to at most 50 users
query.find({
success: function(objects) {
var amount = objects.length;
var indexNum = Math.floor((Math.random() * amount));
var newpartner = objects[indexNum];
if (amount > 0 && newpartner.id !=currentuser.id) {
newpartner.set("searching", 0);
var Firstplayer = Parse.Object.extend("GameMessages");
var firstplayer = new Firstplayer();
var Secondplayer = Parse.Object.extend("GameMessages");
var secondplayer = new Secondplayer();
firstplayer.set("sender", currentuser.id);
firstplayer.set("receiver", newpartner.id);
firstplayer.set("sent",0);
firstplayer.set("received",0);
firstplayer.set("receiverName", newpartner.getUsername());
secondplayer.set("sender", newpartner.id);
secondplayer.set("receiver", currentuser.id);
secondplayer.set("sent",0);
secondplayer.set("received",0);
secondplayer.set("receiverName", currentuser.getUsername());
firstplayer.save().then(function(secondplayer){ <<<
return secondplayer.save(); <<<
}).then(function(firstplayer_update) { <<<
return firstplayer.save({ otherside: secondplayer.id}); <<<
}).then(function(secondplayer_update){ <<<
return secondplayer.save({ otherside: firstplayer.id}); <<<
});
newpartner.save(null, {useMasterKey: true});
}
else {
currentuser.set("searching", 1);
}
currentuser.save();
response.success(amount);
},
error: function(error) {
alert("Error: " + error.code = " " + error.message);
}
});
});
我添加了箭头来显示＆＃34;其他的＆＃34;是。它们不在实际代码中。我不怀疑代码有错误，我不知道javascript。我只是通过研究parse.com文档来编写它。
答案 0 :(得分：0)
firstplayer.save();
secondplayer.save();
secondplayer.set("otherside",firstplayer.id); <<<
firstplayer.set("otherside",secondplayer.id); <<<
firstplayer.save();
secondplayer.save();
这是您说不起作用的代码部分。在解析文档中，您可以看到.save()是非阻塞操作。意味着行firstplayer.save()立即进入下一行（它不会阻止线程进行保存）。因此，当您设置ID secondplayer.set("otherside",firstplayer.id)时，firstplayer.id仍未定义。
所以如果你想要一个同步逻辑，比如save first_object，那么保存second_object， 你必须使用回电。
first_object.save({
success: function(saved_first_object) {
second_object.save({
success: function(saved_second_object) {
//process complete
},
failure: function(error){
}
})
},
failure: function(error) {
console.log(error);
}
})
你也可以使用promises来接近它。 http://blog.parse.com/2013/01/29/whats-so-great-about-javascript-promises/
更新：基于OP尝试承诺的问题编辑
试试这个
firstplayer.save()
.then(function(saved_firstPlayer){
firstplayer = saved_firstPlayer;
return secondplayer.save();
}).then(function(saved_secondplayer) {
secondplayer = saved_secondplayer;
return firstplayer.save({ otherside: secondplayer.id});
}).then(function(updated_firstplayer){
firstplayer = updated_firstplayer;
return secondplayer.save({ otherside: firstplayer.id});
}).then(function(updated_secondlayer){
secondplayer= update_secondplayer;
});
答案 1 :(得分：0)
我不相信创建这两条独立的消息并将它们链接在一起是有意义的，但我不会让这阻碍让这个工作起作用。这还没有经过测试，但我已经重构了你的代码，并认为你应该尝试从中收集一些东西。
// Set this up once, outside of your function, and use it everywhere
var GameMessage = Parse.Object.extend("GameMessages");
Parse.Cloud.define("findpartner", function(request, response) {
// Code defensively, make sure this function requires a user be logged in.
if (!request.user) {
console.log("non-user called findpartner");
return response.error("Unauthorized.");
}
// Get the user who called the function
var user = request.user;
// The end response is a number, apparently
var result = 0;
// The target player
var targetPlayer;
// The two messages that will be used if a match is found
var firstmsg = new GameMessage();
var secondmsg = new GameMessage();
// Create a Users query
var query = new Parse.Query(Parse.User);
query.equalTo("searching", 1);
query.notEqualTo("objectId", user.id);
query.limit(50);
// Remove public access to Find operations for Users in the Data Browser
// Use the master key to query, and use promise syntax.
query.find({ useMasterKey: true }).then(function(objects) {
result = objects.length;
// If no users were found searching, mark the user as searching and save
if (result == 0) {
user.set('searching', 1);
// Return the save promise
return user.save(null, { useMasterKey: true });
}
// Pick a random user out of the response
var indexNum = Math.floor((Math.random() * objects.length));
var targetPlayer = objects[indexNum];
// Set that user to no longer be searching and save
targetPlayer.set("searching", 0);
return targetPlayer.save(null, { useMasterKey: true }).then(function() {
firstmsg.set("sender", user.id);
firstmsg.set("receiver", targetPlayer.id);
firstmsg.set("sent", 0);
firstmsg.set("received", 0);
firstmsg.set("receiverName", targetPlayer.getUsername());
secondmsg.set("sender", targetPlayer.id);
secondmsg.set("receiver", user.id);
secondmsg.set("sent", 0);
secondmsg.set("received", 0);
secondmsg.set("receiverName", user.getUsername());
// Return the promise result of saving both messages
return Parse.Object.saveAll([firstmsg, secondmsg], { useMasterKey: true });
}).then(function(messages) {
// Set the pointers to reference each other
firstmsg.set("otherside", secondmsg.id);
secondmsg.set("otherside", firstmsg.id);
// Return the promise result of saving both messages, again
return Parse.Object.saveAll([firstmsg, secondmsg], { useMasterKey: true });
});
}).then(function() {
// All the stuff above has finished one way or the other, now we just need to
// send back the result. 0 if no match was made.
response.success(result);
}, function(error) {
response.error(error);
});
});