如何使用NgModule导出const
如何使用NgModule导出const
提问于 2018-01-27 00:05:27
我有一个常量，它应该可以被其他导入我的模块使用。
我有Datepicker指令，它定义了日期格式常量(我有这样的指令，所以使用我指令的人可以使用这些常量)：
export const DATETIME_FORMAT = 'DD/MM/YYYY HH:mm:ss';
export const DATE_FORMAT = 'DD/MM/YYYY';
export const TIME_FORMAT = 'DD/MM/YYYY';以及用于进一步输出它们的NgModule。构建此模块，然后在其他项目/模块中使用。
import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import { DatepickerDirective, TIME_FORMAT, DATETIME_FORMAT, DATE_FORMAT } from './datepicker.directive';
@NgModule({
imports: [
CommonModule
],
exports: [
DatepickerDirective,
DATE_FORMAT,
DATETIME_FORMAT,
TIME_FORMAT
],
declarations: [
DatepickerDirective
]
})
export class DatepickerModule { }但是当我尝试构建它时，我得到了错误：
ERROR in src/app/datepicker/datepicker.module.ts(5,11): error TS2345: Argument of type '{ imports: (typeof CommonModule)[]; exports: (string | typeof DatepickerDirective)[]; declara...' is not assignable to parameter of type 'NgModule'.
Types of property 'exports' are incompatible.
Type '(string | typeof DatepickerDirective)[]' is not assignable to type '(any[] | Type<any>)[]'.
Type 'string | typeof DatepickerDirective' is not assignable to type 'any[] | Type<any>'.
Type 'string' is not assignable to type 'any[] | Type<any>'.回答 1
Stack Overflow用户
回答已采纳
发布于 2018-01-27 00:36:36
NgModule 不能导出常量，但您可以使用InjectionToken提供这些值。查找有关InjectionToken here的更多信息。
import { ModuleWithProviders, NgModule, InjectionToken } from '@angular/core';
import { CommonModule } from '@angular/common';
import { DatepickerDirective, TIME_FORMAT, DATETIME_FORMAT, DATE_FORMAT } from './datepicker.directive';
export interface IDatepickerFormats {
TIME_FORMAT: string;
DATETIME_FORMAT: string;
DATE_FORMAT: string;
}
export const DATEPICKER_FORMATS = new InjectionToken<IDatepickerFormats>('datepicker.formats');
@NgModule({
imports: [CommonModule],
exports: [DatepickerDirective],
declarations: [DatepickerDirective]
})
export class DatepickerModule {
static forRoot(): ModuleWithProviders {
return {
ngModule: DatepickerModule,
providers: [
{
provide: DATEPICKER_FORMATS,
useValue: {TIME_FORMAT, DATETIME_FORMAT, DATE_FORMAT}
}
]
};
}
}现在，导入Datepicker模块的每个模块都可以注入，并在其声明的组件中使用这些常量。例如：
import { Component, Inject} from '@angular/core';
import { DATEPICKER_FORMATS, IDatepickerFormats } from './datepicker';
@Component({
selector: 'app-example',
templateUrl: './app-example.component.html',
styleUrls: ['./app-example.component.scss']
})
export class AppExampleComponent {
private DATE_FORMAT: string;
private TIME_FORMAT: string;
private DATETIME_FORMAT: string;
constructor(@Inject(DATEPICKER_FORMATS) private datePickerFormats: IDatepickerFormats) {
this.DATE_FORMAT = this.datePickerFormats.DATE_FORMAT;
this.TIME_FORMAT = this.datePickerFormats.TIME_FORMAT;
this.DATETIME_FORMAT = this.datePickerFormats.DATETIME_FORMAT;
}
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/48465071
复制相关文章
相似问题
腾讯云开发者
