What is the best approach for setting up a global pipe that can be utilized across various modules?

Question

What is the best approach for setting up a global pipe that can be utilized across various modules?

One of my Angular projects includes a custom pipe called 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 outputRate = this.currencyStorage.getCurrencyRate(localStorage.getItem('currency'));
    return value / inputRate * outputRate;
  }
}

I encountered an issue while trying to use this pipe in two different modules - Module1 and Module2. When I imported it into both modules, I received an error indicating that it should be declared at a higher level module.

To resolve this, I decided to declare the pipe within the app.module.ts file.

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 { }

However, upon attempting to use the pipe in Module1, another error was thrown:

The pipe 'currConvert' could not be found

angular typescript pipe angular-module

Answer 1

Answer №1

When working with Angular, a useful technique for sharing common directives, components, pipes, and more is to utilize what is known as a shared module.

These modules declare and export shared elements, making them accessible for use in any of your other modules.

If you're interested in delving deeper into the concept of shared modules, the fundamentals section in the Angular documentation provides valuable insights.

Let's consider, for instance, the currConvert pipe.

Create a new NgModule named ApplicationPipesModule
Include the pipe in the declarations and exports arrays within the metadata of the NgModule decorator

Ensure that any necessary modules for the pipe to function are added to the imports array

// application-pipes.module.ts
// additional imports
import { CurrConvertPipe } from './{your-path}';

@NgModule({
  imports: [
    // dependent modules
  ],
  declarations: [ 
    CurrConvertPipe
  ],
  exports: [
    CurrConvertPipe
  ]
})
export class ApplicationPipesModule {}

Import the newly created ApplicationPipesModule into modules where the pipe will be used by including it in the imports array

// my-module1.module.ts
// additional imports
import { ApplicationPipesModule } from './{your-path}';   

@NgModule({
 imports: [
   // other dependent modules
   ApplicationPipesModule
 ],
 declarations: [],
 exports: []
})
export class MyModule1 {}

Answer 2

When working with Angular, a useful technique for sharing common directives, components, pipes, and more is to utilize what is known as a shared module.

These modules declare and export shared elements, making them accessible for use in any of your other modules.

If you're interested in delving deeper into the concept of shared modules, the fundamentals section in the Angular documentation provides valuable insights.

Let's consider, for instance, the currConvert pipe.

Create a new NgModule named ApplicationPipesModule
Include the pipe in the declarations and exports arrays within the metadata of the NgModule decorator

Ensure that any necessary modules for the pipe to function are added to the imports array

// application-pipes.module.ts
// additional imports
import { CurrConvertPipe } from './{your-path}';

@NgModule({
  imports: [
    // dependent modules
  ],
  declarations: [ 
    CurrConvertPipe
  ],
  exports: [
    CurrConvertPipe
  ]
})
export class ApplicationPipesModule {}

Import the newly created ApplicationPipesModule into modules where the pipe will be used by including it in the imports array

// my-module1.module.ts
// additional imports
import { ApplicationPipesModule } from './{your-path}';   

@NgModule({
 imports: [
   // other dependent modules
   ApplicationPipesModule
 ],
 declarations: [],
 exports: []
})
export class MyModule1 {}

Answer 3

Answer №2

Utilize Sharing Modules to distribute your services, directives, pipes, and components.

Create a module and import the necessary pipes, directives, services, or components. Define the declarations, exports, and providers for the services.

Import the sharing module wherever you need it and make use of its functionalities.

Pipes and directives are typically declared and exported in NgModules metadata. For services, use the forRoot method which provides access to 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 {}

You can follow a similar approach for other modules as well.

Answer 4

Utilize Sharing Modules to distribute your services, directives, pipes, and components.

Create a module and import the necessary pipes, directives, services, or components. Define the declarations, exports, and providers for the services.

Import the sharing module wherever you need it and make use of its functionalities.

Pipes and directives are typically declared and exported in NgModules metadata. For services, use the forRoot method which provides access to 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 {}

You can follow a similar approach for other modules as well.

Answer 5

Answer №3

If you have the following structure:

app 
 -shared
   -components
     -DateComponentModule.ts
   -pipes
     -DatesPipe
     -DatesPipeModule.ts
     
 -SharedModule.ts

When using DatesPipeModule in DateComponentModule.

Declare and Export DatesPipe in DatesPipeModule
Then 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 DateComponentModule{}

You can also export it from SharedModule and import it in DatesComponentModule.ts, but SharedModule will not load before pipes, so an error may occur.

Answer 6

If you have the following structure:

app 
 -shared
   -components
     -DateComponentModule.ts
   -pipes
     -DatesPipe
     -DatesPipeModule.ts
     
 -SharedModule.ts

When using DatesPipeModule in DateComponentModule.

Declare and Export DatesPipe in DatesPipeModule
Then 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 DateComponentModule{}

You can also export it from SharedModule and import it in DatesComponentModule.ts, but SharedModule will not load before pipes, so an error may occur.

Answer 7

Answer №4

To organize your code better, create a module like AppUtilitiesModule and define your pipe within it. Make sure to export the pipe in AppUtilitiesModule and then include the module in both MainModule and SecondaryModule. For detailed information, refer to this useful resource from Angular's official documentation: https://angular.io/docs/ts/latest/guide/ngmodule.html#!#shared-module

Answer 8

To organize your code better, create a module like AppUtilitiesModule and define your pipe within it. Make sure to export the pipe in AppUtilitiesModule and then include the module in both MainModule and SecondaryModule. For detailed information, refer to this useful resource from Angular's official documentation: https://angular.io/docs/ts/latest/guide/ngmodule.html#!#shared-module

Answer 9

Answer №5

When creating a pipe through the CLI for a shared module, it is essential to manually include the pipe in the 'exports' list. I encountered an error with my pipe in the browser until I ensured that the pipe was properly exported within the shared module where it was imported and declared.

Answer 10

When creating a pipe through the CLI for a shared module, it is essential to manually include the pipe in the 'exports' list. I encountered an error with my pipe in the browser until I ensured that the pipe was properly exported within the shared module where it was imported and declared.

What is the best approach for setting up a global pipe that can be utilized across various modules?

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

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