如何在我的情况下返回一个对象？

Question

我有一个函数可能会返回常规对象或http请求对象。

我有类似

var t = function() { 
    var obj 
    var test; 
    //code to determine test value 

//return object depends on test value, 
//if test is undefined, return regular obj, 
//if not make a http request. 
    if (!test){ 
      return obj; 
    } 
    return getObj(url) 
     .then(function(obj){ 
      return obj 
     }) 
} 

var getObj = function() { 
    return $http.get(url);  
} 

var open = function() { 
    //this won't work for regular object, it has to be http object 
    return t() 
     .then(function(obj) { 
      return obj; 
     }) 
} 

var obj = open(); 

如何检查是否返回的对象是通过HTTP请求或只是一个普通的对象呢？

感谢您的帮助！

Answer 1

如果我正确的理解问题是与t返回的对象是一个承诺或不启用c海宁。您可以始终使用$q.when(obj)包装对象，这样可以确保返回的对象始终是承诺，并且可以链接在一起。您需要确保按照您的方式$http注入$q。或者用var obj = $q.when(value)和return obj包装测试值本身。

var t = function() { 
    var obj; 
    var test; 
    //code to determine test value 
    if (!test){ 
     return $q.when(obj); //<-- return $q.when 
    } 
    return getObj(url) 
     .then(function(obj){ 
      return obj 
     }) 
} 

var getObj = function() { 
    return $http.get(url);  
} 

var open = function() { 
    //this will always work now on 
    //return t(); should be enough as well 
    return t() 
     .then(function(obj) { 
      return obj; 
     }) 
} 

when(value):Wraps an object that might be a value or a (3rd party) then-able promise into a $q promise. This is useful when you are dealing with an object that might or might not be a promise, or if the promise comes from a source that can't be trusted.

Answer 2

您可以检查t的类型是函数还是对象。为了被调用，它必须作为函数键入。

//this won't work for regular object, it has to be http object 
if(typeof t !== "function"){ 
//return; or handle case where t is a plain object 
} 

Answer 3

您可以验证返回的对象是否具有承诺的对象或不：

var open = function() { 
    var result = t(); 
    //Verify whether the return object has a promise object or not 
    if(angular.isObject(result.promise) 
    return result 
     .then(function(obj) { 
      return obj; 
     }) 
} 

Answer 4

修改后的代码

传递一个回调方法

var t = function(cb) { 
    var obj 
    var test; 
    //code to determine test value 

//return object depends on test value, 
//if test is undefined, return regular obj, 
//if not make a http request. 
    if (!test){ 
      cb(obj); 
    } 
    return getObj(url) 
     .then(function(obj){ 
      cb(obj) 
     }) 
} 

var getObj = function() { 
    return $http.get(url);  
} 

var open = function() { 
    //this won't work for regular object, it has to be http object 
    return t(function(obj) { 
      // write code dependent on obj 
     }) 
} 

var obj = open();