我有一个特定的情况，我不确定是否应该实现回调或 promise 。我对 promise 完全陌生，刚刚开始理解它的概念。因此我不想陷入 anti patterns .
我也阅读并重新阅读了 Angular 文档 $q .
这就是我想要实现的:
如果使用 promise :
OauthService.token().then(function(access_token){
config.url = config.url+'?access_token='+access_token;
});
return config;
如果使用回调:
OauthService.token(function(access_token){
config.url = config.url+'?access_token='+access_token;
});
return config;
Oauth 服务不仅仅是一个 http 请求，如果它实际上有一些条件，可以让我认为我应该使用回调而不是 promise 。
所以我的服务现在使用回调。
OauthService.js:
app.factory('OauthService', function($http, $localStorage) {
return {
token : function(callback){
// Get actual token
access_token = $localStorage.getObject('access_token');
// Get actual identity
identity_token = $localStorage.getObject('identity_token');
// IF no user logged
if(isObjectEmpty(identity_token)){
// IF access_token does NOT exist OR will expires soon
if( isObjectEmpty(access_token) || Date.now() > (access_token.expires_at - (600*1000)) ){
// Create an anonymous access_token
$http
.get(domain+'/oauth/v2/token?client_id='+public_id+'&client_secret='+secret+'&grant_type=client_credentials')
.then(function (response) {
$localStorage.setObject('access_token', {
key: response.data.access_token,
type: 'anonymous',
expires_at: Date.now()+(response.data.expires_in*1000)
});
// return access token here
callback(response.data.access_token);
});
}
}
// IF user is logged
else{
// IF access_token does NOT exist OR will expires soon OR is anonymous
if( isObjectEmpty(access_token) || Date.now() > (access_token.expires_at - (600*1000)) || access_token.type == 'anonymous' ){
// Create an access_token with an identity
$http
.get(domain+'/oauth/v2/token?client_id='+public_id+'&client_secret='+secret+'&api_key='+identity_token+'&grant_type=http://oauth2.dev/grants/api_key')
.then(function (response) {
$localStorage.setObject('access_token', {
key: response.data.access_token,
type: 'identity',
expires_at: Date.now()+(response.data.expires_in*1000)
});
// return access token here
callback(response.data.access_token);
});
}
}
// return access token here (if the previous token has not changed of type or expired)
callback(access_token.key);
}
};
})
那么，如果我宁愿接受 promise ，我应该如何实现呢？
最佳答案
操作中的条件与回调与 promise 无关。普通回调是一种执行异步操作的蹩脚方式，您应该尽可能使用 Promise。
您可以重写您的 token 方法以使用如下 promise :
app.factory('OauthService', function($http, $localStorage, $q) {
return {
token : function(callback){
// Get actual token
access_token = $localStorage.getObject('access_token');
// Get actual identity
identity_token = $localStorage.getObject('identity_token');
// IF no user logged
if(isObjectEmpty(identity_token)){
// IF access_token does NOT exist OR will expires soon
if( isObjectEmpty(access_token) ||
Date.now() > (access_token.expires_at - (600*1000)) ){
// Create an anonymous access_token
return $http
.get(domain+'/oauth/v2/token?client_id='+public_id +
'&client_secret=' + secret + '&grant_type=client_credentials')
.then(function (response) {
$localStorage.setObject('access_token', {
key: response.data.access_token,
type: 'anonymous',
expires_at: Date.now() +
(response.data.expires_in * 1000)
});
return response.data.access_token;
});
}
}
// IF user is logged
else {
// IF access_token does NOT exist OR will expire soon OR is anonymous
if( isObjectEmpty(access_token) ||
Date.now() > (access_token.expires_at - (600*1000)) ||
access_token.type == 'anonymous' ){
// Create an access_token with an identity
return $http
.get(domain+'/oauth/v2/token?client_id='+public_id+'&client_secret='+secret +
'&api_key='+identity_token+'&grant_type=http://oauth2.dev/grants/api_key')
.then(function (response) {
$localStorage.setObject('access_token', {
key: response.data.access_token,
type: 'identity',
expires_at: Date.now()+
(response.data.expires_in * 1000)
});
return response.data.access_token;
});
}
}
// return access token here (if the previous token has not changed of type or expired)
return $q.when(access_token.key);
}
};
});
然后您可以进行一些重构，将其简化为:
app.factory('OauthService', function($http, $localStorage, $q) {
function expiresSoon(access_token) {
return Date.now() > (access_token.expires_at - (600*1000));
}
function getAccessToken(url, type) {
return $http
.get(url)
.then(function (response) {
$localStorage.setObject('access_token', {
key: response.data.access_token,
type: type,
expires_at: Date.now() +
(response.data.expires_in * 1000)
});
return response.data.access_token;
});
}
return {
token : function(callback){
// Get actual token
access_token = $localStorage.getObject('access_token');
// Get actual identity
identity_token = $localStorage.getObject('identity_token');
// IF no user logged
if(isObjectEmpty(identity_token)){
// IF access_token does NOT exist OR will expires soon
if( isObjectEmpty(access_token) || expiresSoon(access_token) ) {
var url = domain + '/oauth/v2/token?client_id=' + public_id +
'&client_secret=' + secret + '&grant_type=client_credentials';
// Create an anonymous access_token
return getAccessToken(url, 'anonymous');
}
}
// IF user is logged
else {
// IF access_token does NOT exist OR will expire soon OR is anonymous
if( isObjectEmpty(access_token) ||
expiresSoon(access_token) ||
access_token.type == 'anonymous' ){
var url = domain+'/oauth/v2/token?client_id=' + public_id+
'&client_secret='+secret +
'&api_key='+identity_token +
'&grant_type=http://oauth2.dev/grants/api_key';
// Create an access_token with an identity
return getAccessToken(url, 'identity');
}
}
// return access token here (if the previous token has not changed of type or expired)
return $q.when(access_token.key);
}
};
});
关于javascript - AngularJs : Callback or promise in a service using conditions，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/30639796/