我有一个AngularJS服务,我想使用一些异步数据进行初始化。像这样:
myModule.service('MyService', function($http) {
var myData = null;
$http.get('data.json').success(function (data) {
myData = data;
});
return {
setData: function (data) {
myData = data;
},
doStuff: function () {
return myData.getSomeData();
}
};
});
显然,这是行不通的,因为如果doStuff()
在myData
返回之前尝试调用某些方法,则会得到一个空指针异常。据我从阅读这里和这里提出的其他一些问题中所知道的,我有一些选择,但是它们似乎都不是很干净(也许我错过了一些东西):
安装服务“运行”
设置我的应用时,请执行以下操作:
myApp.run(function ($http, MyService) {
$http.get('data.json').success(function (data) {
MyService.setData(data);
});
});
然后我的服务将如下所示:
myModule.service('MyService', function() {
var myData = null;
return {
setData: function (data) {
myData = data;
},
doStuff: function () {
return myData.getSomeData();
}
};
});
这有时会起作用,但是如果异步数据恰好比初始化所有东西花费的时间更长,则在我调用时会得到一个空指针异常 doStuff()
使用承诺对象
This would probably work. The only downside it everywhere I call MyService I will have to know that doStuff() returns a promise and all the code will have to us then
to interact with the promise. I would rather just wait until myData is back before loading the my application.
Manual Bootstrap
angular.element(document).ready(function() {
$.getJSON("data.json", function (data) {
// can't initialize the data here because the service doesn't exist yet
angular.bootstrap(document);
// too late to initialize here because something may have already
// tried to call doStuff() and would have got a null pointer exception
});
});
Global Javascript Var I could send my JSON directly to a global Javascript variable:
HTML:
<script type="text/javascript" src="data.js"></script>
data.js:
var dataForMyService = {
// myData here
};
Then it would be available when initializing MyService
:
myModule.service('MyService', function() {
var myData = dataForMyService;
return {
doStuff: function () {
return myData.getSomeData();
}
};
});
This would work too, but then I have a global javascript variable which smells bad.
Are these my only options? Are one of these options better than the others? I know this is a pretty long question, but I wanted to show that I have tried to explore all my options. Any guidance would greatly be appreciated.
另外,在执行实际的控制器之前,您可以使用以下技术在全球范围内配置服务:https : //stackoverflow.com/a/27050497/1056679。只需全局解析您的数据,然后将其
run
例如以块形式传递给您的服务。