问题描述
您需要异步库。
例如,
for(var i = 0; i < listObj.result.length; i++) {
varBody.index = i;
varBody.memberID = listObj.result[i].program_member.id;
request(
...
, function () {
// Do more Stuff
});
}
可以这样写:
async.forEachOf(listObj.result, function (result, i, callback) {
varBody.index = i;
varBody.memberID = result.program_member.id;
request(
...
, function () {
// Do more Stuff
// The next iteration WON'T START until callback is called
callback();
});
}, function () {
// We're done looping in this function!
});
异步中有很多方便的实用程序函数,这些函数使回调的使用变得更加容易。
解决方法
我正在制作一个经常刷新数据的函数,而我的请求链存在问题。问题是我有一个运行异步请求的for循环,并且for循环将在请求完成之前完成。
setInterval(function(){ // this updates the total hours of all members every 10 seconds
request({ // this gets all of the loyalty program members
url: "",//omitted
method: "GET"
},function(listError,listResponse,listBody) {
if(listError == null && listResponse.statusCode == 200) {
var varBody = {};
var listObj = JSON.parse(listBody);
for(var i = 0; i < listObj.result.length; i++) { // parses through all of the members to update their hours
console.log(i);//****PRINT STATEMENT
varBody.index = i;
varBody.memberID = listObj.result[i].program_member.id;
request({ //we do this request to get the steam ID of the program member
url: "",//omitted
method: "GET"
},function(fanError,fanResponse,fanBody) {
var fan = JSON.parse(fanBody);
if(fanError == null && fanResponse.statusCode == 200 && fan.result.profiles.length != 0) { // make sure that the profile isn't empty
request({
url:"",//omitted
method: "GET"
},function(hourError,hourResponse,hourBody) {
if (hourError == null && hourResponse.statusCode == 200) {
var gameList = JSON.parse(hourBody);
var minutes = 0;
for (var j = 0; j < gameList.response.games.length; j++) { // for loop to calculate the minutes each user has on steam
minutes += gameList.response.games[j].playtime_forever;
}
var deltaHours = 1;
if(deltaHours != 0) {
var transaction = { // updated member object to be inserted
pointsearned: deltaHours,pointsused: 0,loyaltyprogram_id: loyaltyID,programmember_id: memberID
};
request({ // POST request to update the member
url: "",//omitted
method: "POST",body: JSON.stringify(transaction),headers: {
"Content-Type": "application/json"
}
},function(updateError,updateRes,updateBody) {
if(updateError == null && updateRes.statusCode == 200) {
console.log("Success");//****PRINT STATEMENT
}
}
);
}
}
}
);
}
}
);
}
}
console.log("Users Updated"); //****PRINT STATEMENT
}
);
},10000);
如果我要运行此代码,它将显示:
0
1
2
3
Success
Success
Success
Success
我知道是什么问题。事实上,for循环不会等待请求完成。我不知道这是一种解决方法。有人有什么想法吗?