Angular2：在组件上找不到管道装饰器

Question

我在 Angular 2.0-rc1 应用程序中使用了一些非常标准的自定义管道。一切都很好，直到我将管道移动到一个新文件夹。现在我得到：

zone.js:461 Unhandled Promise rejection: No Pipe decorator found on RoomDetailWidgetComponent ; Zone: angular ; Task: Promise.then ; Value: BaseException {message: "No Pipe decorator found on RoomDetailWidgetComponent", stack: "Error: No Pipe decorator found on RoomDetailWidget…/@angular/compiler/src/runtime_compiler.js:66:49)"}message: "No Pipe decorator found on RoomDetailWidgetComponent"stack: "Error: No Pipe decorator found on RoomDetailWidgetComponent↵ at new BaseException (http://localhost:5000/lib/@angular/compiler/src/facade/exceptions.js:17:23)↵ at PipeResolver.resolve (http://localhost:5000/lib/@angular/compiler/src/pipe_resolver.js:29:15)↵ at CompileMetadataResolver.getPipeMetadata (http://localhost:5000/lib/@angular/compiler/src/metadata_resolver.js:142:47)↵ at eval (http://localhost:5000/lib/@angular/compiler/src/metadata_resolver.js:173:57)↵ at Array.map (native)↵ at CompileMetadataResolver.getViewPipesMetadata (http://localhost:5000/lib/@angular/compiler/src/metadata_resolver.js:173:22)↵ at eval (http://localhost:5000/lib/@angular/compiler/src/runtime_compiler.js:80:58)↵ at Array.forEach (native)↵ at RuntimeCompiler._compileComponent (http://localhost:5000/lib/@angular/compiler/src/runtime_compiler.js:76:36)↵ at eval (http://localhost:5000/lib/@angular/compiler/src/runtime_compiler.js:66:49)"proto: ErrorconsoleError @ zone.js:461_loop_1 @ zone.js:490drainMicroTaskQueue @ zone.js:494ZoneTask.invoke @ zone.js:426 zone.js:463 Error: Uncaught (in promise): No Pipe decorator found on RoomDetailWidgetComponent(…)consoleError @ zone.js:463_loop_1 @ zone.js:490drainMicroTaskQueue @ zone.js:494ZoneTask.invoke @ zone.js:426

import { Component, AfterViewInit, Input, SimpleChange, Output, EventEmitter } from "@angular/core";
import { IPropertyRoom } from "./../../shared/propertyData";
import { FirstHalfPipe } from "./../../shared/pipes/first-half.pipe";
import { SecondHalfPipe } from "./../../shared/pipes/second-half.pipe";

export interface IRoomData {
    roomId: number;
    isFeatured: boolean;
    roomName: string;
    featurePicSrc: string;
    description: string;
    amenities: string[];
}

@Component({
    selector: "room-detail-widget",
    templateUrl: "app/mobile/roomDetailWidget/room-detail-widget.html",
    directives: [],
    pipes: [FirstHalfPipe,SecondHalfPipe]
})
export class RoomDetailWidgetComponent {
    @Input() roomDetail: IRoomData;
    @Output() onRoomTabClick = new EventEmitter();

    constructor() {

    }

    ngOnChanges(changes: { [propName: string]: SimpleChange }) {
        this.roomDetail = changes["roomDetail"].currentValue;

    }
    roomClick() {
        this.onRoomTabClick.emit(this.roomDetail.roomId);

    }

    

}

如您所见，我正在组件中声明管道。路径都可以。无法弄清楚如何解决这个问题。

Answer 1

管道不支持继承。这只是一个猜测，但我记得看到一个延伸另一个 class 的管道导致了这个错误。 https://github.com/angular/angular/issues/8694

Answer 2

Angular2 似乎可以找到管道的元数据。

添加 Pipe 装饰器时，会添加以下内容。

[PipeMetadata]
  0: PipeMetadata
    _pure: undefined
    name: "some"
    pure: (...)
    __proto__: InjectableMetadata
  length:1
  __proto__: Array[0]

看到这个 plunkr：https://plnkr.co/edit/d0gXbGm3mus1cQLE1wgB?p=preview。

可能您指向包含管道的模块的路径不正确，因此您导入的管道为空...

Answer 3

事实证明这是一个 "dumb" 错误。

我在父组件中不小心将有问题的组件引用为管道，而不是指令，如下所示：

import { RoomDetailWidgetComponent, IRoomData } from "./../roomDetailWidget/room-detail-widget.component"

@Component({
    directives: [],
    selector: "parent",
    templateUrl: "path/parent.html",
    pipes: [RoomDetailWidgetComponent]  //Duh, big FAIL
})
export class ParentComponent {
 

    constructor() {

    }
    
    
}

希望这有助于避免其他人头疼。容易犯的错误...

Answer 4

我在 Angular10 项目中使用了 TimeAgoPipe https://www.npmjs.com/package/time-ago-pipe。就我而言，“TimeAgoPipe”仅用于 Angular2 项目。

所以对于 Angular10 我们需要使用 “ngx-timeago”

请参考：https://www.npmjs.com/package/ngx-timeago

简短片段：

包-json: "ngx-timeago":"^2.0.0"

App.module.ts: 内部导入数组 => importsTimeagoModule.forRoot()

Shared.module.ts：在 Exports 数组中添加 => TimeagoModule

testpipe.html：“{{日期 | timeago}}”

Angular2：在组件上找不到管道装饰器

Angular2: No Pipe decorator found on Component

angular

pipes-filters