即使这些值在浏览器中呈现,我也会遇到这些错误。我不确定如何解决此问题。
错误TypeError:无法读取未定义的属性'length'
错误TypeError:无法读取未定义的属性'FirstName'
Component.ts:
teams: Team[];
ngOnInit() {
this.getTeams();
}
constructor(private m: DataManagerService, private router: Router) {
}
getTeams(): void {
this.m.getTeams().subscribe(teams => this.teams = teams);
}
select(em: Team){
this.router.navigate(['/teamView',em._id]);
}
Component.html:
<div class="panel-body">
<table class="table table-striped">
<tr>
<th>Team name</th>
<th>Name of Team Leader</th>
</tr>
<tr *ngFor='let team of teams' (click)="select(team)">
<td>{{team.TeamName}}</td>
<td>{{team.TeamLead.FirstName}} {{team.TeamLead.LastName}}</td>
</tr>
</table>
<hr>
</div>
Team.ts:
export class Team {
_id: string;
TeamName: string;
TeamLead: Employee;
Projects:{};
Employees: {};
}
目的:
DataManagerService.ts
teams: Team[];
projects: Project[];
employees: Employee[];
constructor(private http: HttpClient) {
}
getTeams(): Observable<Team[]> {
return this.http.get<Team[]>(`${this.url}/teams`)
}
getProjects(): Observable<Project[]> {
return this.http.get<Project[]>(`${this.url}/projects`)
}
getEmployees(): Observable<Employee[]> {
return this.http.get<Employee[]>(`${this.url}/employees`)
}
<tr *ngIf='teams.length > 0' *ngFor='let team of teams' (click)="select(team)">
<td>{{team?.TeamName}}</td>
<td>{{team?.TeamLead?.FirstName}} {{team?.TeamLead?.LastName}}</td>
</tr>
可能性:a)尚未填充Teams对象。因此,没有什么可重复的b)您的API响应没有所有预期的属性。
像我上面建议的那样添加检查应该可以解决您的问题。LMK,如果我可以进一步解释。
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