如何解决在定义之前需要应用类型的问题？

Question

我走进了一个有趣的问题。这里是我的类型

export interface QuestionPrimative { 
    question : string; 
    id   : string; 
    name  : string; 
    formctrl? : string; 
    formgrp? : string; 
    lowExtreme? : string; 
    hiExtreme? : string; 
    template : string; 
} 

export interface Answer { 
    answer  : string; 
    id   : string; 
    trigger? : string; 
    formctrl? : string; 
} 

export interface QuestionBase extends QuestionPrimative { 
    answers?: Answer[]; 
} 

export interface MicroQuestions { 
    activate? : string; 
    questions? : QuestionBase[]; // I actually want this to be Question[] 
} 

export interface Question extends QuestionBase { 
    micros? : MicroQuestions[]; 
} 

我加载到一个Angular 2 Component我创造了我的问卷，自动处理问题的任何风格我扔在这。为了让为我做什么更好的例子，为什么我形这里的一切这种方式是整个模型的注释版本

//The data when it iterates into Component 
question : string;   // the question to be asked 
id   : string;   // id attribute for HTML 
name  : string;   // name attribute for HTML 
formctrl? : string;   // if element will be a form control 
formgrp? : string;   // if element will be a form group 
template : string;   // matches *ngIf on appropriate chunk of HTML 
answers? : Answer[];   // available answers if multiple choice 
lowExtreme? : string;   // low extreme if question involves rating 
hiExtreme? : string;   // hi extreme for rating 
micros?  : MicroQuestions[]; // if more questions are available 

//if answers are available..... 
answer  : string;   // the answer 
id   : string;   // id attribute for HTML 
trigger? : string;   // used to trigger another tier of questions 
formctrl? : string;   // if element needs to be a form control 

//if there is another tier of questions ...... 
activate? : string;   // matches with the 'trigger' in the answer to know to load 
questions? : QuestionBase[]; // the next tier of questions(which I want to have micros) 

有谁知道我可以键入这个在一个循环的工作，它需要的方式至？

Answer 1

只需更换QuestionBase与Question和它工作得很好：

export interface QuestionPrimative { 
    question: string; 
    id: string; 
    name: string; 
    formctrl?: string; 
    formgrp?: string; 
    lowExtreme?: string; 
    hiExtreme?: string; 
    template: string; 
} 

export interface Answer { 
    answer: string; 
    id: string; 
    trigger?: string; 
    formctrl?: string; 
} 

export interface QuestionBase extends QuestionPrimative { 
    answers?: Answer[]; 
} 

export interface MicroQuestions { 
    activate?: string; 
    questions?: Question[]; // Works 
} 

export interface Question extends QuestionBase { 
    micros?: MicroQuestions[]; 
}