Angular2 rc6 检查后表达式发生了变化

Question

我已按照 http://almerosteyn.com/2016/04/linkup-custom-control-to-ngcontrol-ngmodel 上的教程创建自定义元素。

有一个表单有两个字段：一个自定义组件和另一个通过 ngmodel 链接到同一字段的组件（输入字段）。

当我在自定义组件中编辑值时，它抛出异常 "ORIGINAL EXCEPTION: Expression has changed after it was checked. "。但是，正常字段中的更改会正确触发对自定义元素的更改。

这是代码：

<custom-component [control]="surname1" [(ngModel)]="person.surname1" [name]="'surname1'" formControlName="surname1">Add surname:</custom-component>

<input type="text" name="surname2" id="surname2" formControlName="surname1" [(ngModel)]="person.surname1" />

自定义元素：

const noop = () => {};

export const CUSTOM_INPUT_CONTROL_VALUE_ACCESSOR: any = {
    provide: NG_VALUE_ACCESSOR,
    useExisting: forwardRef(() => MyInputComponent2),
    multi: true
};

@Component({
    selector: 'custom-component',
    template: `<label><ng-content></ng-content></label>
                    <input type="text"  name="{{name}}" [(ngModel)]="value" 
                        (ngModelChange)="changed($event)"

                        (blur)="onBlur()"
                    />
    `,
    providers: [CUSTOM_INPUT_CONTROL_VALUE_ACCESSOR]
})
export class CustomComponent implements ControlValueAccessor {

    @Input() control: FormControl;
    @Input() name: any;
    private innerValue: any = '';

    private onTouchedCallback: () => void = noop;
    private onChangeCallback: (_: any) => void = noop;

    //get accessor
    get value(): any {
        return this.innerValue;
    };

    //set accessor including call the onchange callback
    set value(v: any) {
        if (v !== this.innerValue) {
            this.innerValue = v;
            this.onChangeCallback(v);
        }
    }

    //Set touched on blur
    changed(event) {
        this.onTouchedCallback();
    }

    onBlur() {
        this.onTouchedCallback();
    }

    //From ControlValueAccessor interface
    writeValue(value: any) {
        if (value !== this.innerValue) {
            this.innerValue = value;
        }
    }

    //From ControlValueAccessor interface
    registerOnChange(fn: any) {
        this.onChangeCallback = fn;
    }

    //From ControlValueAccessor interface
    registerOnTouched(fn: any) {
        this.onTouchedCallback = fn;
    }
}

使用enableProdMode()解决；但不能在开发中使用它

****错误（Chrome 输出）:

core.umd.js:5995 异常：./MFormComponent class MFormComponent 中的错误 - 内联 template:55:117 原因：表达式在检查后已更改。先前值：'surtest'。当前值：'surtes'.

core.umd.js:5997 原始异常：表达式在检查后已更改。先前值：'surtest'。当前值：'surtes'

在 ExpressionChangedAfterItHasBeenCheckedError.Error（本地）在 ExpressionChangedAfterItHasBeenCheckedError.BaseError [作为构造函数] (http://localhost:8085/templatetest/js/@angular/core/bundles/core.umd.js:1456:38) 在新的 ExpressionChangedAfterItHasBeenCheckedError (http://localhost:8085/templatetest/js/@angular/core/bundles/core.umd.js:8078:20)

Answer 1

我猜这是因为您对 <custom-component> 和 <input> 使用相同的 formControlName="surename1"。
如果你想将它们绑定到同一个模型，那么只需指向它 ngModel 但为每个模型创建一个控件。

Angular2 rc6 检查后表达式发生了变化

Angular2 rc6 Expression has changed after it was checked

custom-component

typescript

angular