[英]Angular object change detection
I have a third party angular component which is a table displaying the user data. 我有一个第三方角度组件,它是一个显示用户数据的表。 If the passed object to the table changes, the table updates itself.
如果传递给表的对象发生更改,表将自行更新。
How does Angular detect changes to an object? Angular如何检测对象的变化? I have following example:
我有以下示例:
user.component.ts
: user.component.ts
:
@Component({
selector: 'app-user',
templateUrl: './user.component.html',
styleUrls: ['./user.component.css'],
})
export class UserComponent implements OnInit {
private _users: User[];
set users(users: User[]) {
this._users = users;
}
get users(): User[] {
return this._users;
}
constructor() {}
addUserToTheList(user: User) {
// this won't be detected as a change to the object
this.users.push(user);
// on the other hand, this will
let userList: User[] = this.users;
userList.push(user);
this.users = userList;
}
}
Does that mean I have to completely replace the object to trigger the change detection or am I somehow completely missing the point? 这是否意味着我必须完全替换对象以触发更改检测,或者我在某种程度上完全忽略了这一点? Or could it be a problem with the third party library (which is
Clarity Design System
) 或者它可能是第三方库(
Clarity Design System
)的问题
The table component you are using is probably implementing ChangeDetectionStrategy.OnPush
. 您正在使用的表组件可能正在实现
ChangeDetectionStrategy.OnPush
。
This means that the component will treat all input as immutable (meaning it can never change), and therefor only run change detection if the input object is replaced . 这意味着组件将所有输入视为不可变 (意味着它永远不会更改),因此只有在更换输入对象时才会运行更改检测 。
Here is a link explaining it a bit more: https://angular-2-training-book.rangle.io/handout/change-detection/change_detection_strategy_onpush.html 这是一个解释它的链接: https : //angular-2-training-book.rangle.io/handout/change-detection/change_detection_strategy_onpush.html
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