[英]Multiple Template Reference Variables - Angular 2 and TypeScript
我試圖在一個組件中調用一個函數,該函數將一些數據發送到另一個組件中的函數,完成一些操作,然后將數據發送回原始組件。 這些組件是同級的。 我的問題是,Angular在一個html文件中似乎不喜歡多個參考變量,說我的參考變量之一未定義。 有任何想法嗎?
的HTML
<docked-component-picker #compPicker (onComponentRelease)="grid.getMousePosition($event)" [(model)]="model" *ngIf="model.pageState == 1"></docked-component-picker>
<grid #grid (onGetReleaseBack)="compPicker.setNewComponentPosition($event)" [(model)]="model.layout" [editable]="model.pageState" [currentResponsiveRestriction]="model.currentResponsiveRestriction"></grid>
停靠組件選擇器
@Component({
selector: 'docked-component-picker',
templateUrl: './docked-component-picker.component.html',
providers: [ComponentService]
})
export class DockedComponentPickerComponent {
@Input()
private model: Page;
@Output()
private onComponentRelease: EventEmitter<any> = new EventEmitter();
private components;
private currComponent;
private dragging: boolean;
private parentWidth;
constructor(private _componentService: ComponentService, private _componentFactoryResolver: ComponentFactoryResolver, private _elementRef: ElementRef) {
let promise = this._componentService.getComponents().then(response => {
this.components = JSON.parse(response._body);
});
}
@HostListener('window:mouseup', ['$event'])
onMouseup(event) {
console.log(event);
if (this.dragging) {
this.dragging = false;
this.onComponentRelease.emit(event);
}
}
public setNewComponentPosition(event) {
let pc = new PageComponent({
component: this.currComponent.template,
componentId: this.currComponent.id,
pageId: this.model.id,
responsiveRestrictions: [
new ResponsiveRestriction({ sizeType: 0, positionX: event.x, positionY: event.y }),
new ResponsiveRestriction({ sizeType: 1, positionX: event.x, positionY: event.y }),
new ResponsiveRestriction({ sizeType: 2, positionX: event.x, positionY: event.y }),
],
});
this.model.layout.addPageComponent(pc, this.model.currentResponsiveRestriction);
}
/**
* Converts the given container's raw pixel position to grid co-ordinates
* @param source - the container to convert
*/
private convertToGridPosition(x, y): Position {
return new Position(Math.round(x / (this.parentWidth / this.model.layout.width)), Math.round(x / this.model.layout.rowHeight));
}
public createComponent(component): void {
this.currComponent = component;
this.dragging = true;
}
grid.component.ts的所需部分
@Output()
private onGetReleaseBack: EventEmitter<Position> = new EventEmitter();
public getMousePosition(event) {
let pos = new Position(Math.round(event.offsetX / (this.parentWidth / this.model.width)), Math.round(event.offsetY / this.model.rowHeight));
this.onGetReleaseBack.emit(pos);
}
錯誤
錯誤TypeError:無法在handleEvent處讀取Object.eval上未定義的屬性'setNewComponentPosition'[作為handleEvent](PageComponent.html:4)
對接的組件選擇器和網格都位於同一組件內。 您正在嘗試從網格發射器函數“ onGetReleaseBack”捕獲事件以在DockedComponentPickerComponent內部執行一些邏輯。
如果我的理解是正確的,這里是我的建議:在你的組件DockedComponentPickerComponent取代由@input功能setNewComponentPosition:
@Input() set componentPosition(event){
if(event){
//setNewComponentPosition logic here
}
}
然后,您將需要進行其他一些調整才能使其正常工作。 在父模板中,替換您的
<grid #grid
(onGetReleaseBack)="setNewComponentPosition($event)"
[(model)]="model.layout"
[editable]="model.pageState"
[currentResponsiveRestriction]="model.currentResponsiveRestriction">
</grid>
在父組件中,您需要創建一個名為setNewComponentPosition的新函數,該函數將更新您還需要聲明的類屬性“ componentPosition”
setNewComponentPosition(newPosition){
this.componentPosition = newPosition;
}
最后,在父模板中,您需要更新docked-component-picker ...以包括新創建的屬性,如下所示:
<docked-component-picker #compPicker
[componentPosition]="componentPosition"
(onComponentRelease)="grid.getMousePosition($event)"
[(model)]="model"
*ngIf="model.pageState == 1"></docked-component-picker>
問題是因為一起使用ngIf
和#compPicker
。 當視圖初始化compPicker時,它似乎還不存在,因此該變量將是未定義的。
一種解決方案是在您的父組件內部添加ViewChild
來訪問使用ngIf
的子組件:
@ViewChild('compPicker') compPicker: ElementRef;
另一種解決方案是使用[hidden]="model.pageState != 1"
代替ngIf
。
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