Dan*_*ish 6 javascript asynchronous node.js async-await sails.js
我是nodejs的新手,它是回调地狱,我读到了节点8中的async/await简介,并有兴趣以这种方式实现它
我有一组特定的方法需要以trello API的方式一个接一个地以同步方式调用,例如
你可以想象在nodejs中,这需要相互嵌套的重要回调来访问前一个对象
createProjectBoard: function (project) {
t.post("1/board", {
name: project.name,
desc: project.description,
defaultLists: false
}, function (err, board) {
if (err) {
console.log(err);
throw err;
}
//get board id from data
let boardId = board.id
let backlogListId = "";
let highId = "", mediumId = "", lowId = "";
//create labels
t.post("1/labels", {
name: 'High',
color: 'red',
idBoard: boardId
}, function (err, label) {
console.log(err || 'High label created');
if (err) return;
highId = label.id;
});
t.post("1/labels", {
name: 'Medium',
color: 'orange',
idBoard: boardId
}, function (err, label) {
console.log(err || 'Medium label created');
if (err) return;
mediumId = label.id;
});
t.post("1/labels", {
name: 'Low',
color: 'yellow',
idBoard: boardId
}, function (err, label) {
console.log(err || 'Low label created');
if (err) return;
lowId = label.id;
});
//create rest of the lists
t.post("1/lists", { name: "Completed", idBoard: boardId }, function (e, l) {
if (e) {
console.log(e);
return;
}
console.log(l);
t.post("1/lists", { name: "Testing", idBoard: boardId }, function (e, l) {
if (e) {
console.log(e);
return;
}
console.log(l);
t.post("1/lists", { name: "In Progress", idBoard: boardId }, function (e, l) {
if (e) {
console.log(e);
return;
}
console.log(l);
//create backlog list
t.post("1/lists", { name: "Backlog", idBoard: boardId }, function (e, list) {
if (e) {
console.log(e);
return;
}
console.log(list);
backlogListId = list.id;
console.log("backlog card list id:" + backlogListId);
_.each(project.userStories, function (story) {
//assign labels
let labelId = "";
switch (story.complexity.toLowerCase()) {
case 'high':
labelId = highId;
break;
case 'medium':
labelId = mediumId;
break;
default:
labelId = lowId;
}
t.post("1/cards", {
name: story.title,
idLabels: labelId,
idList: backlogListId
}, function (e, card) {
if (e) {
console.log(e);
return;
}
let cardId = card.id;
console.log("created id:" + cardId + ";card:" + story.title);
t.post("1/cards/" + cardId + "/checklists", {
name: "Acceptance Criteria"
}, function (e, checklist) {
if (e) {
console.log(e);
return;
}
console.log('checklist created:');
var clId = checklist.id;
_.each(story.criterion, function (criteria) {
t.post("1/cards/" + cardId + "/checklist/" + clId + "/checkItem", {
name: criteria
}, function (e, checkItem) {
if (e) {
console.log(e);
return;
}
console.log('created check item:' + checkItem);
});
});
});
});
});
});
});
});
});
});
}
我仍然有与上面的代码,其中__问题每个循环受影响,则调用在循环异步所有功能(重新安排项目的顺序它们被认为是原) - 所以我想有必须是一种更好的同步调用方式
我有兴趣使用await/async来清理代码,但是在从异步回调中返回对象时遇到了一些麻烦
该解决方案基于sails.js,以下是我正在编写的TrelloService的摘录
考虑以下:
createProjectBoard: async function(project) {
//get board id from data
let board;
let boardId = "";
let backlogListId = "";
let highId = "",
mediumId = "",
lowId = "";
try {
await t.post("1/board", {
name: project.name,
desc: project.description,
defaultLists: false
},
function(err, b) {
if (err) {
console.log(err);
throw err;
}
console.log("board" + b);
board = b;
});
//create labels
await t.post("1/labels", {
name: 'High',
color: 'red',
idBoard: board.id
}, function(err, label) {
console.log(err || 'High label created');
if (err) return;
highId = label.id;
});
} catch (err) {
console.log(err);
}
}
我需要在标签请求调用中提供board值,到目前为止我无法检索board对象,虽然我设置了await关键字
我需要能够从回调函数中获取对象,并以同步方式将它们用于后续函数调用
我正在使用trello api包装器node-trello进行调用(t)
一种方法是使用回调将上面的函数包含在更多函数中,如下所示,但我认为这不是最佳实践,因为我必须在每个需要使用的对象上编写包装器回调
function foo(url,options,cb){
await t.post(url, options,
function(err, b) {
if (err) {
console.log(err);
throw err;
}
console.log("board" + b);
cb(b);
});
}
var url = "1/board";
var options = {
name: project.name,
desc: project.description,
defaultLists: false
};
foo(url,options,function(board){
console.log(board); //board object
});
任何建议表示赞赏
我有兴趣使用await/async来清除代码
这有两个步骤:promisification和async.您的代码变得混乱,因为它正在跳过第一步.
Promisification在回调函数周围创建了非常简单的promise-returns包装函数.例如,if t是Trello类的实例:
Trello.prototype.postAsync = (url, data) => new Promise((resolve, reject) => {
this.post(url, data, (err, result) => {
if (err) { reject(err); }
else { resolve(result); }
});
});
所述第二步骤是写async/ await逻辑,使用许返回功能和不回调.由于它们是承诺返回的,因此它们的代码更自然:
const board = await t.postAsync("1/board", {
name: project.name,
desc: project.description,
defaultLists: false
});
console.log("board" + board);
//create labels
let highId;
try {
highId = await t.postAsync("1/labels", {
name: 'High',
color: 'red',
idBoard: board.id
});
} catch (err) {
console.log(err || 'High label created');
return;
}
宣传步骤繁琐且重复.有些库可以自动回调承诺,最着名的是Bluebird.
| 归档时间： |
|
| 查看次数： |
4135 次 |
| 最近记录： |