Javascript ES6-允诺。一切在允诺之内。决心
我正在使用Javascript ES6-允诺。一切在允诺之内。决心,javascript,node.js,promise,ecmascript-6,es6-promise,Javascript,Node.js,Promise,Ecmascript 6,Es6 Promise,我正在使用ecmascript 6并试图在我的API中一起执行Promise.resolve()中的Promise.all() 这是我的密码: import jwt from "jsonwebtoken"; import Database from "../../../util/Database"; import send from "../../../util/send"; var updatePosition = function(organizationId, positionId, p
ecmascript 6
并试图在我的API中一起执行Promise.resolve()
中的Promise.all()
这是我的密码:
import jwt from "jsonwebtoken";
import Database from "../../../util/Database";
import send from "../../../util/send";
var updatePosition = function(organizationId, positionId, positionTitle) {
let updatedPosition = {
organization_id: organizationId,
title: positionTitle
};
return Database.connection.query('UPDATE positions SET ? WHERE id=?', [updatedPosition, positionId]);
}
var unLinkUserToPosition = function(positionId) {
return Database.connection.query('UPDATE users SET position_id=NULL WHERE position_id=?', positionId);
}
var linkUserToPosition = function(positionId, userId) {
return Database.connection.query('UPDATE users SET position_id=? WHERE id=?', [positionId, userId]);
}
var getPositionAndCommittees = function(positionId) {
return Promise.all([getPosition(positionId), getCommittees(positionId)]).then(formatJSON);
}
var getPosition = function(positionId) {
return Database.connection.query('SELECT \
p.id as position_id, \
p.title as position_title, \
u.id as user_id, \
u.facebook_UID, \
u.email, \
u.first_name, \
u.last_name, \
u.phone, \
u.semester_joined, \
u.year_joined, \
u.thumbnail_photo_URL, \
u.cover_photo_URL \
FROM positions p \
LEFT JOIN users u ON p.id=u.position_id \
WHERE p.id=? \
ORDER BY p.id ASC', positionId);
}
var getCommittees = function(positionId) {
return Database.connection.query('SELECT \
c.id as committee_id, \
c.title as committee_title, \
u.id as chairmen_user_id, \
u.thumbnail_photo_URL as chairmen_thumbnail_photo_URL, \
u.first_name as chairmen_user_first_name, \
u.last_name as chairmen_user_last_name \
FROM committees c \
LEFT JOIN users u ON c.chairmen_id=u.id \
WHERE c.position_id=? ORDER BY c.title ASC', positionId);
}
var formatJSON = function(results) {
let positionResult = results[0][0];
let committeesResult = results[1];
let position = {
id: positionResult.position_id,
title: positionResult.position_title,
user: {
id: positionResult.user_id,
facebookUID: positionResult.facebook_UID,
email: positionResult.email,
firstName: positionResult.first_name,
lastName: positionResult.last_name,
phone: positionResult.phone,
semesterJoined: positionResult.semester_joined,
yearJoined: positionResult.year_joined,
thumbnailPhotoURL: positionResult.thumbnail_photo_URL,
coverphotoURL: positionResult.cover_photo_URL
},
committees: committeesResult
};
return position;
}
module.exports = function(req, res) {
let token = req.headers['bearer-authorization'];
let tokenSecret = ENV.API_SECRET
let decodedToken = jwt.verify(token, tokenSecret);
let organizationId = 1
let positionId = req.params.positionId;
let positionTitle = req.body.title;
let positionUserId = req.body.userId;
Promise.resolve(updatePosition(organizationId, positionId, positionTitle))
.then(unLinkUserToPosition(positionId))
.then(linkUserToPosition(positionId, positionUserId))
.then(getPositionAndCommittees(positionId))
.then(send.success(res))
.catch(send.failure(res));
};
旁注:我在数据库查询中使用了
promise-mysql
,这意味着当我返回database.connection.query()
,它实际上返回了一个新的promise
以下是
send.success
和send.failure
函数的外观:
var send = {
success: function(response) {
return function(data) {
response.status(200).json(data);
};
},
failure: function(response) {
return function(error) {
var statusCode = error.statusCode || 500;
if (statusCode === TEMPORARY_REDIRECT && error.body && error.body.value) {
response.status(200).json(error.body.value);
return;
}
console.error(error.stack);
response.status(statusCode).json({
message: error.message
});
};
}
}
以下是我试图让函数执行的顺序:
getPosition
和getCommittees
调用Promise.all,并应在getPosition()和getCommittees()完成执行并返回格式化JSON数据后立即调用formatJSONlinkUserToPosition
返回的数据将作为send.success
函数中的数据返回,这意味着Promise.resolve
不会等待getPositionAndCommittees
完成执行Promise.all
以下是输出结果:
{
"fieldCount": 0,
"affectedRows": 1,
"insertId": 0,
"serverStatus": 2,
"warningCount": 0,
"message": "(Rows matched: 1 Changed: 0 Warnings: 0",
"protocol41": true,
"changedRows": 0
}
任何关于我如何完成我正在尝试做的事情的建议都将不胜感激 我认为问题在于几个功能会立即启动,而不仅仅是在前面的步骤完成之后 假设此呼叫链:
updatePosition(organizationId, positionId, positionTitle)
.then(unLinkUserToPosition(positionId))
.then(linkUserToPosition(positionId, positionUserId))
.then(getPositionAndCommittees(positionId))
.then(send.success(res))
.catch(send.failure(res));
这意味着异步函数updatePosition
,unLinkUserToPosition
,linkUserToPosition
和getPositionAndCommittees
都将立即启动。send函数也是,但是由于这些函数返回一个稍后将执行的函数,所以没有问题。这意味着函数立即执行,结果承诺被分配给上一个函数的.then()
,这没有意义,因为它接受一个函数(可能返回承诺),而不是承诺。您需要的是:
updatePosition(organizationId, positionId, positionTitle)
.then(updatePositionResult => unLinkUserToPosition(positionId))
.then(unLinkUserToPositionResult => linkUserToPosition(positionId, positionUserId))
.then(linkUserToPositionResult => getPositionAndCommittees(positionId))
.then(send.success(res))
.catch(send.failure(res));
旁注:我认为你的
承诺。解析功能是多余的。当您为它分配一个承诺(promise that.catch返回的承诺)时,它不会立即得到解决,它也会返回一个承诺。你实际上忽略了承诺,所以你不需要它。您只需使用updatePosition(…)
@Matthias247启动异步操作,谢谢您的提示!我将其更新为以updatePosition()
开头。在getPositionAndCommittees promise完成后调用send.success函数仍然没有成功,因为调用的是JSON格式吗?根据对删除答案的讨论,我认为您的代码看起来不错。我的最后一个想法是:Database.connection.query()返回什么?它是一个普通的javascript对象吗?或者可能是某种游标,其实例被DB库重用?在这种情况下,您可能需要在每个步骤之后将查询结果克隆到一个普通的JSON对象中。DB真的支持并发查询吗?啊,现在我知道了。威尔发布解决方案我甚至不知道我能做到!我得查一下它的功能,但你已经成功了!非常感谢:)看。