中的错误：无法解析SimpleLookupAddEditFormComponent的所有参数在C:\Users/lastr/Source/Repos/SMATA/Code/ng/SMATA ng/src/app/system-list/simple lookup add edit/simple-lookup-add-edit.component.ts：(？，[objectObject]、[Object Object]、[Object Object](。
我试图构建我的angular应用程序，但由于错误而失败
ERROR in : Can't resolve all parameters for SimpleLookupAddEditFormComponent
in C:/Users/lastr/Source/Repos/SMATA/Code/ng/smata-ng/src/app/system-
list/simple-lookup-add-edit/simple-lookup-add-edit.component.ts: (?, [object
Object], [object Object], [object Object]).
这是部件的代码。这是一个基本组件。这里少了什么吗？构造函数属性可能有问题？
import { Component, OnInit } from '@angular/core';
import { SimpleLookupBaseService } from '../services/simple-lookup-base/simple-lookup-base.service';
import { ActivatedRoute, Router } from '@angular/router';
import validationEngine from "devextreme/ui/validation_engine";
import notify from 'devextreme/ui/notify';
@Component({
selector: 'app-simple-lookup-add-edit',
templateUrl: './simple-lookup-add-edit.component.html',
styleUrls: ['./simple-lookup-add-edit.component.css']
})
export class SimpleLookupAddEditFormComponent implements OnInit {
newSystemList: {};
isEditMode:boolean = true;
selectedSystemList: any;
title: string;
saveButtonText: string;
isPopupVisible:boolean = false;
entityId:any;
constructor(
protected _systemListTitle : string,
protected _svc: SimpleLookupBaseService,
protected _router: Router,
protected _route: ActivatedRoute
)
{}
............
.....
}
错误消息中的?问号告诉构造函数中的哪个参数未知。
constructor(
protected _systemListTitle : string,
protected _svc: SimpleLookupBaseService,
protected _router: Router,
protected _route: ActivatedRoute
)
第一个参数是触发?问号。
类型string不是可注射类型。Angular注入器使用参数的类型来推断应该使用的injectable提供程序。
要注入string参数，您必须在其中一个NgModule定义中提供一个令牌。
export const LIST_TITLE: InjectionToken<string> = new InjectionToken<string>('LIST_TITLE');
@NgModule({
providers: [{provide: LIST_TITLE, useValue: 'My List Title'}]
})
现在，您可以手动将令牌注入到构造函数中。
constructor(
@Inject(LIST_TITLE) protected _systemListTitle : string,
protected _svc: SimpleLookupBaseService,
protected _router: Router,
protected _route: ActivatedRoute
)