我在我的 Angular HTML 模板中做错了啥？ [复制]

Posted 2023-02-22

【中文标题】我在我的 Angular HTML 模板中做错了啥？ [复制]

【英文标题】：What I m doing wrong in my Angular HTML template? [duplicate]我在我的 Angular HTML 模板中做错了什么？ [复制]

【发布时间】：2020-02-22 14:15:45

【问题描述】：

在可观察性方面我还不太适应角度，所以我正在训练自己

我正在编写一个管理拳击俱乐部的小应用程序

我想显示当前所选拳击手最近参加的 3 节课

所以我尝试了以下

 <div class="col-6">
        <div *ngIf="lessons">
            <div *ngIf="(lessons|async).length > 0">
                <h2>les 3 derniere lessons </h2>
                <hr>
                <ul class="list-group" style="user-select: auto;">
                    <li *ngFor=" let lesson in (lessons | async) | slice:0:3; let i=index "
                        class="list-group-item d-flex justify-content-between align-items-center"
                        style="user-select: auto;">
                        <a [routerLink]="['/lesson', lesson.id, 'view' ]">
                            <span class="badge badge-primary badge-pill" style="user-select: auto;">i</span>
                            lesson.detail
                        </a>

                    </li>
                </ul>
            </div>

        </div>
        <div *ngIf="versements">
            <div *ngIf="(versements|async).length > 0">
                <h2>les 3 derniere versements </h2>
                <hr>
                <ul class="list-group" style="user-select: auto;">
                    <li *ngFor=" let versement in (versements | async ) | slice:0:3; let i=index "
                        class="list-group-item d-flex justify-content-between align-items-center"
                        style="user-select: auto;">
                        <a [routerLink]="['/lesson', lesson.id, 'view' ]">
                            <span class="badge badge-primary badge-pill" style="user-select: auto;">i</span>
                            versement.montant? : versement.date | date :'short'
                        </a>

                    </li>
                </ul>
            </div>
        </div>

    </div>

其中组件ts代码如下：

import  Component, OnInit  from '@angular/core';
import  ActivatedRoute  from '@angular/router';

import  IBoxer  from 'app/shared/model/boxer.model';
import  JhiDataUtils, JhiAlertService  from 'ng-jhipster';
import  Observable, of  from 'rxjs';
import  MAN_PICTURE_PATH  from 'app/shared/constants/input.constants';
import  IVersement  from 'app/shared/model/versement.model';
import  VersementService  from '../versement/versement.service';
import  LessonService  from '../lesson/lesson.service';
import  HttpResponse, HttpErrorResponse  from '@angular/common/http';
import  ILesson  from 'app/shared/model/lesson.model';

@Component(
  selector: 'jhi-boxer-detail',
  templateUrl: './boxer-detail.component.html'
)
export class BoxerDetailComponent implements OnInit 
  boxer: IBoxer;
  versements: Observable<IVersement[]>;
  lessons : Observable<ILesson[]>;
  manPicturePath: any;

  constructor(
    protected jhiAlertService: JhiAlertService,
    protected activatedRoute: ActivatedRoute,
    protected dataUtils: JhiDataUtils,
    protected versementService: VersementService,
    protected lessonService: LessonService
  ) 

  

  ngOnInit() 
    this.manPicturePath = MAN_PICTURE_PATH;

    this.activatedRoute.data.subscribe(( boxer ) => 
      this.boxer = boxer;
    );


    this.versementService
      .query( boxerID: this.boxer.id , this.versementService.BY_BOXER_ID)
      .subscribe(
        (res: HttpResponse<IVersement[]>) => this.fetchVersementsDatas(res.body),
        (err: HttpErrorResponse) => this.JhiAlertError(err)
      );


    this.lessonService
        .query( boxerID: this.boxer.id,this.lessonService.BY_BOXER_ID)
        .subscribe(
          (res:HttpResponse<ILesson[]>) => this.fetchLessonsDatas(res.body),
          (err:HttpErrorResponse) => this.JhiAlertError(err)
        );

  

  fetchLessonsDatas(lessons)
    this.lessons = of(lessons);
  

  fetchVersementsDatas(versements?: IVersement[]) 
    this.versements = of(versements);
  

  JhiAlertError(errorMessage: any) 
    this.jhiAlertService.error(errorMessage, null, null);

  

  byteSize(field: any) 
    return this.dataUtils.byteSize(field);
  

  openFile(contentType: any, field: any) 
    return this.dataUtils.openFile(contentType, field);
  

  previousState() 
    window.history.back();
  

我的模板处理不好，但我不知道在哪里

这是我的控制台错误提示

core.js?f18e:6014 ERROR Error: Uncaught (in promise): Error: Template parse errors:
Can't bind to 'ngForIn' since it isn't a known property of 'li'. (" > 0"> <h2>les 3 derniere lessons </h2> <hr> <ul class="list-group" style="user-select: auto;"> <li [ERROR ->]*ngFor=" let lesson in (lessons | async) | slice:0:3; let i=index " class="list-group-item d-flex jus"): ng:///BoxingBoxerModule/BoxerDetailComponent.html@0:1790
Property binding ngForIn not used by any directive on an embedded template. Make sure that the property name is spelled correctly and all directives are listed in the "@NgModule.declarations". ("ngth > 0"> <h2>les 3 derniere lessons </h2> <hr> <ul class="list-group" style="user-select: auto;"> [ERROR ->]<li *ngFor=" let lesson in (lessons | async) | slice:0:3; let i=index " class="list-group-item d-flex"): ng:///BoxingBoxerModule/BoxerDetailComponent.html@0:1786
Parser Error: Unexpected end of expression:  versement.montant? : versement.date | date :'short'  at the end of the expression [ versement.montant? : versement.date | date :'short' ] in ng:///BoxingBoxerModule/BoxerDetailComponent.html@0:2622 (".id, 'view' ]"> <span class="badge badge-primary badge-pill" style="user-select: auto;">i</span>[ERROR ->] versement.montant? : versement.date | date :'short' </a> </li> </ul> </div> </div> </div> </"): ng:///BoxingBoxerModule/BoxerDetailComponent.html@0:2622
Parser Error: Conditional expression versement.montant? requires all 3 expressions at the end of the expression [ versement.montant? : versement.date | date :'short' ] in ng:///BoxingBoxerModule/BoxerDetailComponent.html@0:2622 (".id, 'view' ]"> <span class="badge badge-primary badge-pill" style="user-select: auto;">i</span>[ERROR ->] versement.montant? : versement.date | date :'short' </a> </li> </ul> </div> </div> </div> </"): ng:///BoxingBoxerModule/BoxerDetailComponent.html@0:2622
Can't bind to 'ngForIn' since it isn't a known property of 'li'. ("0"> <h2>les 3 derniere versements </h2> <hr> <ul class="list-group" style="user-select: auto;"> <li [ERROR ->]*ngFor=" let versement in (versements | async ) | slice:0:3; let i=index " class="list-group-item d-f"): ng:///BoxingBoxerModule/BoxerDetailComponent.html@0:2310
Property binding ngForIn not used by any directive on an embedded template. Make sure that the property name is spelled correctly and all directives are listed in the "@NgModule.declarations". ("h > 0"> <h2>les 3 derniere versements </h2> <hr> <ul class="list-group" style="user-select: auto;"> [ERROR ->]<li *ngFor=" let versement in (versements | async ) | slice:0:3; let i=index " class="list-group-item"): ng:///BoxingBoxerModule/BoxerDetailComponent.html@0:2306

【问题讨论】：

我现在应该考虑在循环一个简单数组时使用 in 和当我循环一个 observable 时使用 of 吗？

角度模板中没有let item in items。始终使用let item of items

【参考方案1】：

要进行迭代，您需要使用以下语法*ngFor = "let value of values"：

<li *ngFor="let versement of (versements | async ) | slice:0:3; let i=index">
...
</li>

As Angular docs says:

一个结构指令，它为每个项目呈现一个模板 收藏。该指令被放置在一个元素上，该元素成为 克隆模板的父级。

<li *ngFor="let user of userObservable | async as users; index as i; first as isFirst">
  i/users.length. user <span *ngIf="isFirst">default</span>
</li>