模板 Angular5 中显示数据的最佳方法是什么:
我在这里从Firestore(=firebase(加载数据:
ngOnInit() {
this.user = this.authService.afAuth.authState;
this.user.subscribe((auth) => {
if (auth) {
this.itemService.getTestMembers(auth.uid).subscribe(testMembers => {
this.testMembers = testMembers;
});
}
});
}
Firestore 响应为:[{"email":"john@gmail.com","name":"John"}]
1° 模板中显示名称的第一个解决方案:
<span>{{testMembers[0]?.name}}</span>
作品,显示名称,但我有一个错误:TypeError: _co.testMembers is undefined
2° 代码中的第二解显示名称:
userName: string;
ngOnInit() {
this.user = this.authService.afAuth.authState;
this.user.subscribe((auth) => {
if (auth) {
this.itemService.getTestMembers(auth.uid).subscribe(testMembers => {
this.testMembers = testMembers;
**this.userName = (JSON.stringify(testMembers[0].name)); <-- here**
});
}
});
什么是最好的解决方案,或者也许还有另一种解决方案。谢谢 }
服务响应可能存在延迟,因为它是异步的,因此您应该在访问对象之前添加if
条件,如下所示
this.user.subscribe((auth) => {
if (auth) {
this.itemService.getTestMembers(auth.uid).subscribe(testMembers => {
this.testMembers = testMembers;
if(testMembers.length > 0 ) {//////////add this
this.userName = (JSON.stringify(testMembers[0].name));
}
});
}
});
您还可以在 HTML 上添加条件,例如
<span> {{testMembers ? testMembers[0]?.name : ' '}} </span>
由于获取数据可能需要一些时间,并且首先执行HTML,因此这种情况有助于避免此错误。