[英]Angular 7: NullInjectorError: No provider for PagerService
我正在嘗試實現分頁,但它不起作用。 這是我的代碼:
pager.service.ts:
import * as _ from 'underscore';
@Injectable({
providedIn: 'root',
})
export class PagerService {
getPager(totalItems: number, currentPage: number = 1, pageSize: number = 10) {
// calculate total pages
let totalPages = Math.ceil(totalItems / pageSize);
let startPage: number, endPage: number;
if (totalPages <= 10) {
// less than 10 total pages so show all
startPage = 1;
endPage = totalPages;
} else {
// more than 10 total pages so calculate start and end pages
if (currentPage <= 6) {
startPage = 1;
endPage = 10;
} else if (currentPage + 4 >= totalPages) {
startPage = totalPages - 9;
endPage = totalPages;
} else {
startPage = currentPage - 5;
endPage = currentPage + 4;
}
}
// calculate start and end item indexes
let startIndex = (currentPage - 1) * pageSize;
let endIndex = Math.min(startIndex + pageSize - 1, totalItems - 1);
// create an array of pages to ng-repeat in the pager control
let pages = _.range(startPage, endPage + 1);
// return object with all pager properties required by the view
return {
totalItems: totalItems,
currentPage: currentPage,
pageSize: pageSize,
totalPages: totalPages,
startPage: startPage,
endPage: endPage,
startIndex: startIndex,
endIndex: endIndex,
pages: pages
};
}
}
快速工人列表.component.ts:
import { JobService } from '@app/services';
import { PagerService } from './../../../services/pager.service';
import { Component, OnInit, Input } from '@angular/core';
import * as _ from 'underscore';
@Component({
selector: 'app-quick-worker-list',
templateUrl: './quick-worker-list.component.html',
styles: []
})
export class QuickWorkerListComponent implements OnInit {
S3ImageUrl: string;
// array of all items to be paged
private workerData: any[];
// pager object
pager: any = {};
// paged items
pagedItems: any[];
constructor(private pagerService: PagerService, private jobService: JobService) {
}
ngOnInit() {
this.jobService.getQuickJobWorkerList(1301, 1)
.map((response: Response) => response.json())
.subscribe(data => {
// set items to json response
this.workerData = data;
// initialize to page 1
this.setPage(1);
});
}
setPage(page: number) {
if (page < 1 || page > this.pager.totalPages) {
return;
}
// get pager object from service
this.pager = this.pagerService.getPager(this.allItems.length, page);
// get current page of items
this.pagedItems = this.allItems.slice(this.pager.startIndex, this.pager.endIndex + 1);
}
}
我收到此錯誤:
QuickWorkerListComponent_Host.ngfactory.js? [sm]:1 ERROR 錯誤:StaticInjectorError(AppModule)[QuickWorkerListComponent -> PagerService]: StaticInjectorError(Platform: core)[QuickWorkerListComponent -> PagerService]: NullInjectorError: No provider for PagerService! 在 NullInjector.push../node_modules/@angular/core/fesm5/core.js.NullInjector.get (core.js:3228) at resolveToken (core.js:3473) at tryResolveToken (core.js:3417) at StaticInjector .push../node_modules/@angular/core/fesm5/core.js.StaticInjector.get (core.js:3314) at resolveToken (core.js:3473) at tryResolveToken (core.js:3417) at StaticInjector.push ../node_modules/@angular/core/fesm5/core.js.StaticInjector.get (core.js:3314) at resolveNgModuleDep (core.js:19784) at NgModuleRef_.push../node_modules/@angular/core/fesm5 /core.js.NgModuleRef_.get (core.js:20473) 在 resolveNgModuleDep (core.js:19784)
繼錯誤文本,您必須導入並添加PagerService
在你的供應部件app.module.ts
文件:
providers: [
PagerService,
],
並且不要忘記將其聲明為Injectable
:
@Injectable()
export class PagerService {
// ...
}
您的錯誤與PagerService
相關,與下划線PagerService
NullInjectorError: PagerService 沒有提供程序! 在
確保您的服務已在 app.module 的提供商列表中注冊或在頂部具有Injectable
聲明:
@Injectable({
providedIn: 'root',
})
angular 7 中的一個常見服務示例如下:
import { Injectable } from '@angular/core';
@Injectable({
providedIn: 'root',
})
export class MyService{
constructor() { }
}
有關更多詳細信息,請參閱服務文檔。
Page Service 或 Job Service 都應該應用 Injectable 屬性,或者檢查您是否在這些服務中注入了某些內容,然后同樣適用於該屬性。
如果您使用的是單回購:
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