角度 TS 错误 TS1109

Posted 2023-02-22

【中文标题】角度 TS 错误 TS1109

【英文标题】：Angular TS Error TS1109

【发布时间】：2018-06-11 00:31:08

【问题描述】：

我在控制台中收到以下错误：

webpack: 正在编译... 10% 构建模块 0/1 模块 1 活动 ...p/shoppinglist2/src/app/app.module.tsERROR 在 src/app/meal.service.ts(46,56)：错误 TS1109：预期表达式。

日期：2017-12-31T09:55:50.224Z 哈希：8003d6d8f334085afa7f 时间：267ms 块 inline inline.bundle.js (inline) 5.79 kB [entry] 块 main main.bundle.js (main) 73.1 kB [初始] [渲染] 块 polyfills polyfills.bundle.js (polyfills) 558 kB [初始] 块 styles styles.bundle.js (styles) 456 kB [初始] 块 vendor vendor.bundle.js（供应商）11.3 MB [初始]

webpack：编译成功。

我没有看到问题。该代码基于来自 https://angular.io/tutorial/toh-pt6 的 Angular HTTP 示例。 我正在使用 Angular ^5.0.0，rxjs ^5.5.2

meal.service.ts 中的代码：

import  Injectable               from '@angular/core';
import  Observable               from 'rxjs/Observable';
import  catchError, map, tap     from 'rxjs/operators';
import  of                       from 'rxjs/observable/of';
import  HttpClient, HttpHeaders,
         HttpParams               from '@angular/common/http';

import  MessageService           from './message.service';
import  Meal, oneMeal, Meals     from './meal';

const httpOptions = 
  headers: new HttpHeaders('Content-Type': 'application/json')
;

@Injectable()
export class MealService 

  constructor(
    private http: HttpClient,
    private messageService: MessageService
  )  ;

  private mealUrl = 'http://192.168.178.11:1337/api/meal';

  private log(message: string) 
    this.messageService.add('MealService: ' + message);
  ;

  private handleError<T> (operation = 'operation', result?: T) 
    return (error: any): Observable<T> => 
      console.error(error)
      this.log(`$operation failed: $error.message`);
      return of(result as T);
    ;
  

  getMeals (page:number): Observable<Meals> 
    let httpParams = new HttpParams().set('where', '%')
      .set('orderBy', 'meal_id')
      .set('page', page.toString())
      .set('items', '10');
    //this.messageService.add('Debug: ' + httpParams);
    return this.http.get<Meals>(this.mealUrl,  params: httpParams  )
      .pipe(
        tap(meals => this.log(`fetched $meals.count entries`)),
        catchError(this.handleError('getMeals', <Meals>)) // Line 46: the Error
      );
  ;

  getMeal (id:number): Observable<oneMeal> 
    let httpParams = new HttpParams().set('id', id.toString());
    //this.messageService.add(`MealService: fetched meal_id=$id`);
    return this.http.get<oneMeal>(this.mealUrl,  params: httpParams )
      .pipe(
        tap(meal => this.log(`fetched $meal.data[0].meal_name`))//,
        //catchError(this.handleError('getMeal', <oneMeal>))
      );
  

【参考方案1】：

您以错误的方式调用泛型方法，因此您 得到这个 -

src/app/meal.service.ts(46,56) 中的错误：错误 TS1109：表达式 预计

错误的方式

catchError(this.handleError('getMeals', <Meals>)) // Line 46: the Error

正确方法

catchError(this.handleError<Meals>('getMeals'))

---

 getMeals (page:number): Observable<Meals> 
    let httpParams = new HttpParams().set('where', '%')
      .set('orderBy', 'meal_id')
      .set('page', page.toString())
      .set('items', '10');
    //this.messageService.add('Debug: ' + httpParams);
    return this.http.get<Meals>(this.mealUrl,  params: httpParams  )
      .pipe(
        tap(meals => this.log(`fetched $meals.count entries`)),
        catchError(this.handleError<Meals>('getMeals')) // Line 46: the Error
      );
  ;

【讨论】：

如果我这样做，我会收到此错误：ERROR in src/app/meal.service.ts(43,5): error TS2322: Type 'Observable< | Meals>' is not assignable to type 'Observable<Meals>'. Type ' | Meals' is not assignable to type 'Meals'. Type '' is not assignable to type 'Meals'. Property 'count' is missing in type ''. src/app/meal.service.ts(46,56): error TS2345: Argument of type 'typeof Meals' is not assignable to parameter of type 'Meals'. Property 'count' is missing in type 'typeof Meals'.

【参考方案2】：

如果您检查您所引用的文档中的 handleError 函数，您会注意到它期望接收一个参数，

private handleError<T> (operation = 'operation', result?: T) 
return (error: any): Observable<T> => 

  // TODO: send the error to remote logging infrastructure
  console.error(error); // log to console instead

  // TODO: better job of transforming error for user consumption
  this.log(`$operation failed: $error.message`);

  // Let the app keep running by returning an empty result.
  return of(result as T);
 ;

但是在你的代码中，你使用了错误的handleError函数。

getMeals (page:number): Observable<Meals> 
    let httpParams = new HttpParams().set('where', '%')
      .set('orderBy', 'meal_id')
      .set('page', page.toString())
      .set('items', '10');
    //this.messageService.add('Debug: ' + httpParams);
    return this.http.get<Meals>(this.mealUrl,  params: httpParams  )
      .pipe(
        tap(meals => this.log(`fetched $meals.count entries`)),
        catchError(this.handleError('getMeals', <Meals>)) // Line 46: the Error
      );
  ;

这就是你得到这个的原因 - src/app/meal.service.ts(46,56) 中的错误：错误 TS1109：预期表达式。 所以试试这个 -

catchError(this.handleError('getMeals'))

希望对您有所帮助。