angular - 如何正确地将函数传递给 Angular2/Typescript 中的自定义指令?
问题描述
我对 Angular 2 相当陌生。我正在从 AngularJS 升级我的应用程序,现在我正处于 UI/UX 开发的最后阶段。我有最后一个问题需要帮助。先感谢您。
当前计划
- 我有一个自定义指令TspFieldWidgetDirective,它接受多个输入,一个是 function
@Input('onRefresh') public refresh: Function;
。 - TspFieldWidgetDirective元素可以在各种组件中使用,以重新设计标准表单字段。
- 我将当前指令用作TspHeaderComponent模板内的选择框。
- 当用户更改选择框的值时,
OnRefresh
调用该函数来刷新应用程序以更新新公司的视图。
什么不工作
每当tspheaderComponent
OnRefresh
模板都加载到浏览器中时,它就会在函数上产生无限的调用循环,即oncompanyChange,当它仅在选择框更改值时才能调用一次。当我从浏览器更改选择框的值时(在TspFieldWidgetDirective模板内 -
(change)="refresh({'id': fieldData[fieldKey]})"
,会生成以下错误。ERROR TypeError: _co.refresh is not a function
请注意
- 该功能在 Angular 5 中从未运行过,它在 AngularJS 中运行得非常好。
- 除了将函数作为输入传递给指令之外,其他一切都有效。
下面的代码片段:
tsp-header.component.ts
/*
Method to change company of the company selector
@param: id - string
@return: none
*/
public onCompanyChange(id: string): void {
if ((__env.debug && __env.verbose)) {
console.log('Setting current_company_id to ' + id);
}
if (id !== undefined && id !== null)
{
// @TODO: Update user preference on server IF they have permission to change their default company
this.cookies.set('preferences.current_company_id', id);
this.core.app.current_user.preferences.current_company_id = id;
this.core.initApp();
this.router.navigate(['/app/dashboard']);
}
}
tsp-header.html
<!-- company changer -->
<li>
<tsp-field-widget
type="company-select"
[onRefresh]="onCompanyChange(id)"
[showAvatar]="true"
[fieldData]="core.app.current_user.preferences"
fieldKey="current_company_id"
[hideLabel]="true"
[optionData]="core.app.session.base_companies">
</tsp-field-widget>
</li>
tsp-field-widget.component.ts
// Component class
@Component({
selector: 'tsp-field-widget',
templateUrl: './templates/tsp-field-widget.html'
})
export class TspFieldWidgetComponent implements OnInit {
public lang:any; // for i18n
@Input() public type: string; // the field type
@Input() public isRequired: boolean; // is the field required
@Input() public isReadonly: boolean;
@Input() public index: any; // index of ng-repeat
@Input() public filterBy: any; // used in conjunction with ng-repeat
@Input() public orderBy: any; // used in conjunction with ng-repeat
@Input() public fieldData: any; // the record of ng-repeat
@Input() public fieldKey: string; // the index of record - record[fieldKey]
@Input() public placeVal: string; // the placeholder value of the field, usually used for selects and other dropdowns
@Input() public pattern: string; // used for ng-pattern
@Input() public prefix: string; // Text to display before title listings
@Input() public recordId: any; // the ID of the record
@Input() public label: string; // the label for the field for <label> tag
@Input() public suffix: string; // sub label, usually placed below some label or title
@Input() public optionData: any[]; // array of data used to populate selects or to store data values
@Input() public showAvatar: boolean; // show the fields avatar
@Input() public hideLabel: boolean; // show the fields <label>
@Input() public showAdd: boolean; // show the add button (to add new record)
@Input() public showTitle: boolean; // avatar type: show the name of the user
@Input() public showDesc: boolean; // avatar type: show the name of the user
// @Input() public isHighlighted:boolean; // default type: highlight text
@Input() public numRows: string; // textarea: the number of rows of the text area
@Input() public idKey: string; // select: the default ID key for option data - defaults to _id
@Input() public titleKey: string; // select: the default title key for option data - defaults to title
@Input() public descKey: string; // select: the default description key for option data - defaults to description
@Input() public sliderType: string; // percent, amount or default, slider type
@Input() public sliderMinValue: string; // slider type
@Input() public sliderMaxValue: string; // slider type
@Input() public sliderStepValue: string; // slider type
@Input() public sliderOrientation: string; // slider type
@Input() public dzOptions: any; // dropzone options
@Input() public dzCallbacks: any; // dropzone callbacks
@Input() public dzMethods: any; // dropzone methods
@Input() public decimalPlaces: string; // tspFormat type
@Input() public locale: string; // for dates and currency
@Input() public format: string; // for dates
@Input() public formatHours: string; // for dates
@Input() public intervalMins: number; // for dates
@Input() public owner: string; // used for module windows to determine the type of record to add
@Input('onAdd') public add: Function;
@Input('onEdit') public edit: Function;
@Input('onToggle') public toggle: Function;
@Input('onDelete') public delete: Function;
@Input('onRefresh') public refresh: Function;
constructor(private el: ElementRef,
private cookies: TspCookiesService,
public core: TspCoreService,
private object: TspObjectService,
public date: TspDateService) {
this.lang = core.lang;
this.date = date;
}
}
tsp-field-widget.html
<div *ngIf="type=='company-select'">
<select class="company-select"
class="form-control"
[(ngModel)]="fieldData[fieldKey]"
(change)="refresh({'id': fieldData[fieldKey]})"
data-parsley-trigger="change">
<option [selected]="x[idKey] === fieldData[fieldKey]" *ngFor="let x of optionData" [ngValue]="x[idKey]">
{{x[titleKey]}}
</option>
</select>
</div>
解决方案
Angular 的变更检测在视图初始化期间已经被触发。但此时 refresh() 可能仍为空/未定义。
我建议不要直接调用 'refresh()' 而是一个可以检查 refresh() 是否已经传入的包装方法。
在你的tsp-field-widget.html中有这样的东西:
(change)="doRefresh({'id': fieldData[fieldKey]})"
这在你的tsp-field-widget.component.ts
private doRefresh(object: any): void {
if(refresh) {
refresh(object);
}
}
这样,您可以确保仅在刷新已存在时才调用它。
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