Angular 8 NgFor 仅支持绑定(bind)到 Iterables，例如 Arrays error 和 Acces Control Allow origin

Question

我有一个模型:

export class Employe {    
    constructor(public id?: any,
        public nom?: String,
        public prenom?: String,
        public cin?: String){}    
}

employees.component.ts

ngOnInit(){
    this.loadEmployes();
}    

 pageEmployes:any={};

  loadEmployes():Observable<any>{    
     this.http.get("http://localhost:8080/api/employe").subscribe(
      data=>{
        console.log(data);
        this.pageEmployes = data;

      }, err=>{
        console.log(err);
      }
    );
    return this.pageEmployes;
  }

employees.component.html

 <tr *ngFor="let item of pageEmployes">         
      <td>{{item.nom}}</td>
      <td>{{item.prenom}}</td>    
    </tr>

CollaborateurController.java

@RestController

@RequestMapping("/api/employe")

@CrossOrigin("*")

public class CollaborateurController {

    @Autowired
    private CollaborateurRepository collaborateurRepository;

    @RequestMapping(value="", method=RequestMethod.GET)
    public List<Collaborateur> getEmp() {
        return (List<Collaborateur>) collaborateurRepository.findAll();
    }

这会引发错误:

ERROR Error: Cannot find a differ supporting object '[object Object]' of type 'object'. NgFor only supports binding to Iterables such as Arrays.

Access to XMLHttpRequest at 'http://localhost:8080/api/employe' from origin 'http://localhost:4200' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.

Answer 1

从您的代码示例来看，您正在尝试迭代(循环)一个对象，不是数组。

这部分是错误的:

pageEmployes:any={};

并且应该改为:

pageEmployes: Employe[] = [];

“={};”初始化一个新的对象。

“=[];”初始化一个新的可迭代列表