我试图弄清楚如何在AMS Javascript API中使用Promises。
这是我创建的两个功能，即“承诺”
function checkUsername(username, table) {
return table.where({username: username}).read({
success: function (results) {
if (results.length === 0) {
return true;
} else {
return false;
}
},
error: function(error) {
return false;
}
});
}
function checkEmail(email, table) {
return table.where({email: email}).read({
success: function (results) {
if (results.length === 0) {
return true;
} else {
return false;
}
},
error: function(error) {
return false;
}
});
}
checkUsername(body.username, accountsTable).then(function (results) {
if (results) {
return checkEmail(body.email, accountsTable);
} else {
response.send(400, {message: 'This username is already in use.'});
}
}).then(function(results) {
if (results) {
response.send(200, {message: 'Can proceed with sign up.'});
} else {
response.send(400, {message: 'This email address is already in use.'});
}
});
我试图像在Parse中那样使用承诺，但它显然不起作用。控制台日志不断吐出内部服务器错误，而.then（）不是对象的函数。我假设我缺少一个要求或东西以便拥有Promises功能？
Error in script '/api/register.js'. TypeError: Cannot call method 'done' of undefined
at exports.post (D:\home\site\wwwroot\App_Data\config\scripts\api\register.js:30:59)
[external code]
答案 0 :(得分：2)
我已经意识到我做错了什么。
我现在决定将Q节点模块用于我的承诺。
var q = require('q');
exports.post = function(request, response) {
// Use "request.service" to access features of your mobile service, e.g.:
// var push = request.service.push;
var tables = request.service.tables;
var accountsTable = tables.getTable('Accounts');
var params = request.body;
checkUsername(params.username, accountsTable).then(function (result) {
if (result.length === 0) {
return checkEmail(params.email, accountsTable);
} else {
response.send(400, {message: 'This username is in use.'});
}
}).then(function (results) {
if (results.length === 0) {
return;
} else {
response.send(400, {message: 'This email address is already registered.'});
}
}).then(function () {
response.send(200, {message: 'Username and email are unique. You can register!'});
});
};
function checkUsername(username, table) {
var deferred = q.defer();
table.where({username: username}).read({
success: function (result) {
deferred.resolve(result);
},
error: function (error) {
deferred.reject(error);
}
});
return deferred.promise;
}
function checkEmail(email, table) {
var deferred = q.defer();
table.where({email: email}).read({
success: function (result) {
deferred.resolve(result);
},
error: function (error) {
deferred.reject(error);
}
});
return deferred.promise;
}