错误类型错误：无法读取未定义的属性“first_name”答案

【问题标题】：ERROR TypeError: Cannot read property 'first_name' of undefined错误类型错误：无法读取未定义的属性“first_name”
【发布时间】：2020-07-04 22:50:51
【问题描述】：

我收到此错误当我尝试从后端服务将列表呈现到视图时，能够获取响应数据并将其记录到控制台，但它不会呈现在视图上。

在此处输入代码

import { Component, OnInit, Input } from '@angular/core';
import { StudentsService } from '../services/students.service';
import { Student } from '../interfaces/Student';

@Component({
  selector: 'app-student',
  templateUrl: './student.component.html',
  styleUrls: ['./student.component.css'],
})
export class StudentComponent implements OnInit {
  @Input() student: Student;
  students: Student[];
  constructor(private studentService: StudentsService) {}

  ngOnInit() {
    this.studentService.getStudents().subscribe((students) => {
      (data) => {
        this.students = data.json();
        Array.of(this.students);
      };
      console.log(students);
    });
  }
}

export interface Student {
  id: number;
  first_name: string;
  last_name: string;
  date_of_birth: Date;
}

<div class="container mt-5">
  <ul *ngFor="let student of students">
    <li>{{student.first_name}}</li>
  </ul>
</div>

【问题讨论】：

标签： javascript html angular typescript

【解决方案1】：

   (data) => {
        this.students = data.json();
        Array.of(this.students);
      };

它不应该是一个函数。把它改成这样：

import { Component, OnInit, Input } from '@angular/core';
import { StudentsService } from '../services/students.service';
import { Student } from '../interfaces/Student';

@Component({
  selector: 'app-student',
  templateUrl: './student.component.html',
  styleUrls: ['./student.component.css'],
})
export class StudentComponent implements OnInit {
  @Input() student: Student;
  students: Student[];
  constructor(private studentService: StudentsService) {}

  ngOnInit() {
          this.studentService.getStudents().subscribe((students) => {
      this.students = students; // students is response from server. if it is not Student[] you should map it to correct type.
    });
  }
}

【讨论】：