流星从异步函数中获取值

Question

我从流星中的wrapAsync函数获取返回值时遇到了问题。以下是我的代码

Template.greet.helpers({ 
    greet : function() { 
    var convertAsyncToSync = Meteor.wrapAsync(HTTP.get); 
    resultOfAsyncToSync = convertAsyncToSync('http://www.demo.com/api/greet', {}); 
    console.log(resultOfAsyncToSync); 
    return resultOfAsyncToSync; 
    } 
}); 

我在控制台中得到未定义的值。

Answer 1

尝试

Template.greet.onCreated(function(){ 
    this.apiResult = new ReactiveVar(null); 
}) 
Template.greet.helpers({ 
    greet : function() { 
    var t = Template.instance(); 
    HTTP.get('http://www.demo.com/api/greet', {}, function(e,r){ 
     //process response and save it in reactivevar 
     t.apiResult.set(r.data); 
    }); 
    return t.apiResult.get(); 
    } 
}); 

不要忘记补充包meteor add reactive-var

编辑

Template.greet.onRendered(function(){ 
    var t = Template.instance(); 
    HTTP.get('http://www.demo.com/api/greet', {}, function(e,r){ 
    //process response and save it in reactivevar 
    t.apiResult.set(r.data); 
    }); 
}) 

Template.greet.helpers({ 
    greet : function() { 
    var t = Template.instance(); 
    return t.apiResult.get(); 
    } 
});