How to declare a pipe globally to use in different modules?
I have a custom pipe named CurrConvertPipe
import {Pipe, PipeTransform} from '@angular/core';
import {LocalStorageService} from './local-storage';
@Pipe({name: 'currConvert', pure: false})
export class CurrConvertPipe implements PipeTransform {
constructor(private currencyStorage: LocalStorageService) {}
transform(value: number): number {
let inputRate = this.currencyStorage.getCurrencyRate('EUR');
let outputputRate = this.currencyStorage.getCurrencyRate(localStorage.getItem('currency'));
return value / inputRate * outputputRate;
}
}
I need to use this in two different modules, Module1
and Module2
.
When I import in Module1
and Module2
, I get an error saying it should be declared in a higher level module.
So I declare the pipe inside the app.module.ts
import './rxjs-extensions';
import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';
import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';
import { CurrConvertPipe } from './services/currency/currency-pipe';
@NgModule({
imports: [
BrowserModule,
FormsModule,
HttpModule,
AppRoutingModule,
Module1,
Module2
],
declarations: [
AppComponent,
CurrConvertPipe
],
providers: [
],
bootstrap: [AppComponent]
})
export class AppModule { }
But when I use it in Module1
, it throws an error
The pipe 'currConvert' could not be found
In Angular a good technique for sharing common directives, components, pipes, etc. is to use a so called shared module.
Those modules declare and export common parts, to make them usable for any of your other modules.
The fundamentals section of the angular documentation is a very good read about shared modules.
Let's take as example your currConvert
pipe.
Declare new NgModule called
ApplicationPipesModule
Add the pipe to the
declarations
andexports
arrays of theNgModule
-decorator metadata-
Add any modules that may be required for your pipe to work to the
imports
array// application-pipes.module.ts // other imports import { CurrConvertPipe } from './{your-path}'; @NgModule({ imports: [ // dep modules ], declarations: [ CurrConvertPipe ], exports: [ CurrConvertPipe ] }) export class ApplicationPipesModule {}
-
import the created
ApplicationPipesModule
module into the modules where your pipe is going to be used, by adding it to theimports
array// my-module1.module.ts // other imports import { ApplicationPipesModule } from './{your-path}'; @NgModule({ imports: [ // other dep modules ApplicationPipesModule ], declarations: [], exports: [] }) export class MyModule1 {}
you can use Sharing Modules for share your service, directive, pipes, components
you have to create an module and import the pipes ,directive, services or components and set the declaration, export and providers for the services.
import the sharing module in to where ever you want and use it.
basically pipes and directives declared and exported in NgModules meta data. for services define forRoot which returns the providers to access other modules.
-
shareModule.ts
import { NgModule, ModuleWithProviders } from '@angular/core'; import { appDirective } from './{your-path}'; import { appPipe } from './{your-path}'; import { appService } from './{your-path}'; @NgModule({ declarations: [ appPipe, appDirective ], exports: [ appPipe, appDirective ] }) export class SharingModule { static forRoot(): ModuleWithProviders { return { ngModule: SharingModule, providers: [ appService ] }; } }
-
my-module1.module.ts
import { BrowserModule } from '@angular/platform-browser'; import { NgModule } from '@angular/core'; import { myComponent } from './{your-path}'; import { SharingModule } from './{your-path}'; @NgModule({ declarations: [ myComponent ], imports: [ BrowserModule, SharingModule.forRoot() ], }) export class AppModule {}
Like wise you can do in othe moduls also.
You should make a module, i.e. SharedModule
and declare your pipe there. Then you should export pipe in SharedModule
and import your SharedModule
in both Module1
and Module2
. There's a great article in Angular's docs: https://angular.io/docs/ts/latest/guide/ngmodule.html#!#shared-module
Consider you have this structure:
app
-shared
-components
-DateComponentModule.ts
-pipes
-DatesPipe
-DatesPipeModule.ts
-SharedModule.ts
When you are using DatesPipeModule in DateComponentModule.
Declare and Export DatesPipe in DatesPipeModule
Now Import DatesPipeModule directly into DateComponentModule.
DatesPipeModule.ts
import { DatesPipe} from './{your-path}';
@NgModule({
imports: [],
declarations: [
DatesPipe
],
exports: [
DatesPipe
]
})
export class DatesPipeModule{}
DateComponentModule.ts
import { DatesPipeModule} from './{your-path}';
@NgModule({
imports: [DatesPipeModule],
declarations: [],
exports: []
})
export class DatesPipeModule{}
You can also export it from SharedModule
and import it in DatesComponentModule.ts
, but SharedModule
will not load before pipes, so it throws an error.
If you generate a pipe using CLI for a shared module you will need to add the pipe to the 'exports' list manually. My pipe error'd in the browser until I added the pipe as an export in my shared module I imported/declared it in.