TypeError：無法讀取角度4中未定義的屬性“ length”

Question

TypeError：無法讀取角度4中未定義的屬性“ length”

這是代碼導出類UserComponent實現OnInit {

  roles:IUserRole[];
  sourseRoles: SelectedItem[];
  selectedRole:any;

BindRoles() {
    this.sourseRoles= [];
    this.sourseRoles.push({ label: "Assign Role", value: null });
    if (this.roles.length > 0) {
      for (let role of this.roles) {
        this.sourseRoles.push({ label: role.Title, value: role.UserRoleId })enter image description here
      }
    }
  }
----------

這是代碼

this.appServiceManager.libGet（“ Role”）.subscribe（（role：any）=> {this.selectedRole = [];

  this.selectedRole = role; this.sourseRoles.push({ label: this.selectedRole.Title, value: this.selectedRole.UserRoleId }) }, (error: any) => { this.msgs = []; this.msgs.push({ severity: 'error', summary: 'Error Message', detail: error }); }); 

----------
<label for="password">User Role</label>
 <p-dropdown name="Title" #Title="ngModel" required (click)="BindRoles()" 

 [(ngModel)]="selectedRole" id="dropdown" [options]="sourseRoles"

 [autoWidth]="false"></p-dropdown>

 <div *ngIf="registerForm.submitted && !Title.valid" class="help-block">Role 
 Information is required</div>

----------

Answer 1

export class UserComponent implements OnInit {
    roles: IUserRole[] = [];     <======= Initialize it =========>
    sourseRoles: SelectedItem[]; <======= Declaration was incorrect =========>
    selectedRole: any;

    BindRoles() {
      if (this.roles.length > 0) {
        for (let role of this.roles) {
          this.sourseRoles.push({ label: role.Title, value: role.UserRoleId })
        }
      }
    }
}

Answer 2

我在TS代碼中看不到這個：

sourseRoles

我看到了您的角色並選擇了角色