Question

我从网络服务Doctor.service.ts获取数据：

*getAllDoctors():Observable<Doctor[]>{
let doctor$ = this.http
  .get(`${this.baseUrl}/users`,{headers: this.getHeaders()})
  .map(mapDoctor)
  return doctor$;}



*function mapDoctor(response:Response):Doctor[]{
return response.json().map(toDoctor);}




*function toDoctor(r:any):Doctor{
let doctor = <Doctor>({
id:r.id,
name:r.name,
username:r.username,
email:r.email,
phone:r.phone,
website:r.website,
company:r.company,
address:r.address,
});
console.log('Parsed doctor:', doctor);
return doctor;
}

在component.ts中，我得到的数据如下：

doctors:Doctor[];

ngOnInit(){
this.doctorService
  .getAllDoctors()
  .subscribe(p => this.doctors = p);
}

问题在于我想在其他方法中使用医生列表，例如通过Key获取医生或获取医生名单......，我创建了这种方法：

getdoctorsById():Doctor[]{
return (this.doctors = this.doctors.filter(doctor => doctor.id ===   this.id));
}

但问题是医生名单未定义，它没有映射到对象Doctor，请我需要一些帮助!!!!!

Answer 1

每次要访问this.doctors时，都必须检查它是否包含元素，如果不是，则返回空数组：

getdoctorsById():Doctor[] {
  if (!this.doctors.length)
    return [];

  return (this.doctors = this.doctors.filter(doctor => doctor.id === this.id));
}

更新：我想我发现了问题。尝试声明doctors这样的数组：

doctors:Doctor[] = [];

通过这个你用空数组初始化这个数组。

<强> UPDATE2 ：

在DoctorService（文件NestedJson.service.ts）中，您以与以前相同的方式声明并访问this.doctors：

doctors:Doctor[];

...

function toDoctor(r:any):Doctor{
  let doctor = <Doctor>({
    id:r.id,
    name:r.name,
    username:r.username,
    email:r.email,
    phone:r.phone,
    website:r.website,
    company:r.company,
    address:r.address,

  });
  console.log('Parsed doctor:', doctor);
  this.doctors.push(doctor); // <== this.doctors === undefined here
  console.log('MMMMMMMMMMMMM',this.doctors);
  return doctor;
}

因此，使用空数组

初始化它

Update3 ：更改getdoctorsById：

getdoctorsById():Doctor[]{
  return this.doctors.filter(doctor => doctor.id ===   this.id);
}

即。删除作业。

将订阅转换为对象

1 个答案: