Angular 角度|无法读取属性'；XXX和x27；未定义的

我使用了2个model.ts

profile.model.ts

export interface Profile {
    username: string;
    nickname: string;
    image: string;
  }

import { Profile } from '.';

export interface Comment {
  author: Profile;
  content: string;
  creatat?: Date;
}

...
export class CommentComponent implements DoCheck {
  ...
  content: string;      // Get value from ngModel in comment.component.html
  comments: Comment;    // comment.model.ts
}
...

  addComment() {
    this.comments.author.nickname = 'Test Nickname';
    this.comments = {
      content: this.content
    };
    ...
  }

'comment.model.ts'使用'profile.model.ts'

comment.model.ts

export interface Profile {
    username: string;
    nickname: string;
    image: string;
  }

import { Profile } from '.';

export interface Comment {
  author: Profile;
  content: string;
  creatat?: Date;
}

...
export class CommentComponent implements DoCheck {
  ...
  content: string;      // Get value from ngModel in comment.component.html
  comments: Comment;    // comment.model.ts
}
...

  addComment() {
    this.comments.author.nickname = 'Test Nickname';
    this.comments = {
      content: this.content
    };
    ...
  }

comment.component.ts

export interface Profile {
    username: string;
    nickname: string;
    image: string;
  }

import { Profile } from '.';

export interface Comment {
  author: Profile;
  content: string;
  creatat?: Date;
}

...
export class CommentComponent implements DoCheck {
  ...
  content: string;      // Get value from ngModel in comment.component.html
  comments: Comment;    // comment.model.ts
}
...

  addComment() {
    this.comments.author.nickname = 'Test Nickname';
    this.comments = {
      content: this.content
    };
    ...
  }

当我运行addComment（）时，出现以下错误

错误类型错误：无法读取未定义的属性“author”

有什么问题

---

提前感谢您的建议。

您需要初始化

注释

属性。目前您只设置了它的类型-

Comment

因为

Profile

的属性不是可选的，所以您需要显式地将它们分配给

null

s

comments: Comment = { 
   author: {  
      username: null,
      nickname: null,
      image: null,
   }, 
   content: null 
}

或者，您可以在属性名称之后添加

？

，使它们成为可选的

export interface Profile {
    username?: string;
    nickname?: string;
    image?: string;
}

然后像这样初始化

comments: Comment = { 
   author: { } 
}