The module has been declared by multiple NgModules

Question

The module has been declared by multiple NgModules

After creating the ExampleComponent component and declaring it in a module that is not listed in app.module, I now want to declare the same ExampleComponent in a module that is included in app.module. How can I achieve this without encountering an error stating that the component is declared by more than one NgModule?

abc.module.ts

import { ExampleComponent } from '../Example/Example.component';
@NgModule({
  declarations: [
    ExampleComponent
  ]
})

app.module.ts

import { NewModule } from '../new/new.component';
@NgModule({
  imports: [
    NewModule
  ],
  declarations: []
})

new.module

import { ExampleComponent } from '../Example/Example.component';
@NgModule({
  declarations: [
    ExampleComponent
  ]
})

angular typescript

Answer 1

Answer №1

When utilizing a component in multiple modules, it implies that the component is being shared among different parts of the application. To ensure better organization and encapsulation, it's advisable to create a dedicated module (let's name it ExampleModule) for your ExampleComponent. This practice allows you to import the module wherever the ExampleComponent is required.

To set up the ExampleModule:

import { NgModule } from '@angular/core';
import { ExampleComponent} from '../Example/Example.component';
@NgModule({
  declarations: [
    ExampleComponent,
  ],
  exports: [
    ExampleComponent,
  ]
})
export class ExampleModule { }

Subsequently, import this module into the desired sections (such as the abc module and app module) where you intend to utilize the ExampleComponent:

import { ExampleModule } from '../example.module';
@NgModule({
  imports: [
    ExampleModule 
  ]
  ...
})

By segregating your shared component into its own module, you establish an encapsulation layer that handles all the necessary dependencies for the component. Consequently, any future consumers merely need to import the module itself without having to worry about individual dependencies.

Answer 2

When utilizing a component in multiple modules, it implies that the component is being shared among different parts of the application. To ensure better organization and encapsulation, it's advisable to create a dedicated module (let's name it ExampleModule) for your ExampleComponent. This practice allows you to import the module wherever the ExampleComponent is required.

To set up the ExampleModule:

import { NgModule } from '@angular/core';
import { ExampleComponent} from '../Example/Example.component';
@NgModule({
  declarations: [
    ExampleComponent,
  ],
  exports: [
    ExampleComponent,
  ]
})
export class ExampleModule { }

Subsequently, import this module into the desired sections (such as the abc module and app module) where you intend to utilize the ExampleComponent:

import { ExampleModule } from '../example.module';
@NgModule({
  imports: [
    ExampleModule 
  ]
  ...
})

By segregating your shared component into its own module, you establish an encapsulation layer that handles all the necessary dependencies for the component. Consequently, any future consumers merely need to import the module itself without having to worry about individual dependencies.

Answer 3

Answer №2

If you encounter this issue, it may be due to importing the component in the app.module.ts file instead of the module file.

Here is an example scenario:

My folder structure looks like this:

app 
   src 
     component 
        general.component.ts 
        general.component.html 
        general.component.scss 
        general.component.spect 
        general.module.ts
        general.model.ts 
        general.services.ts
app.module.ts
app.routing.ts

The error message "The component is declared by more than one NgModule" might appear when

you import in app.module.ts file like this:

import { GeneralComponent } from './component/general/graph.component';

@NgModule({
          declarations: [
           GeneralComponent
          ],
    })

Steps to resolve the issue

Export the general.component within general.module.ts as shown below:

general.module.ts

    import { NgModule } from '@angular/core'
    import { CommonModule } from '@angular/common'
    import { GeneralComponent } from './general.component'    
    @NgModule({
      declarations: [GeneralModule.rootComponent],
      imports: [CommonModule],
      exports: [GeneralModule.rootComponent],
      entryComponents: [GeneralModule.rootComponent],
    })
    export class GeneralModule {
      static rootComponent = GeneralComponent
    }

Import general.module.ts in app.module.ts

app.module.ts

 import { GeneralModule } from './component/graph-general/graph-general.module';
    @NgModule({
      declarations: [
      ],
      imports: [  
         GeneralModule ,
    ]
    }) 
    export class AppModule { 
}

NOTE: Remember to keep components in declarations and modules in imports only.

Answer 4

If you encounter this issue, it may be due to importing the component in the app.module.ts file instead of the module file.

Here is an example scenario:

My folder structure looks like this:

app 
   src 
     component 
        general.component.ts 
        general.component.html 
        general.component.scss 
        general.component.spect 
        general.module.ts
        general.model.ts 
        general.services.ts
app.module.ts
app.routing.ts

The error message "The component is declared by more than one NgModule" might appear when

you import in app.module.ts file like this:

import { GeneralComponent } from './component/general/graph.component';

@NgModule({
          declarations: [
           GeneralComponent
          ],
    })

Steps to resolve the issue

Export the general.component within general.module.ts as shown below:

general.module.ts

    import { NgModule } from '@angular/core'
    import { CommonModule } from '@angular/common'
    import { GeneralComponent } from './general.component'    
    @NgModule({
      declarations: [GeneralModule.rootComponent],
      imports: [CommonModule],
      exports: [GeneralModule.rootComponent],
      entryComponents: [GeneralModule.rootComponent],
    })
    export class GeneralModule {
      static rootComponent = GeneralComponent
    }

Import general.module.ts in app.module.ts

app.module.ts

 import { GeneralModule } from './component/graph-general/graph-general.module';
    @NgModule({
      declarations: [
      ],
      imports: [  
         GeneralModule ,
    ]
    }) 
    export class AppModule { 
}

NOTE: Remember to keep components in declarations and modules in imports only.

Answer 5

Answer №3

When setting up your application in the app.module.ts file, make sure to only import the highest level module that wraps your component.

For example:

layout.module.ts

@NgModule({
  declarations: [
    ToolbarComponent // This is where it should be imported.
  ],
  imports: [
    CommonModule, 
    SharedModule,
  ],
  exports: [
    ToolbarComponent // Also here.
  ]
})
export class LayoutModule { }

app.module.ts

@NgModule({
  declarations: [
    AppComponent,
  ],
  imports: [
    BrowserModule,
    AppRoutingModule,
    BrowserAnimationsModule,
    LayoutModule, // Import LayoutModule here.
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

By following this setup, you will have full access to the

<app-toolbar></app-toolbar>

component selector in your app.component.html just by importing LayoutModule.

Answer 6

When setting up your application in the app.module.ts file, make sure to only import the highest level module that wraps your component.

For example:

layout.module.ts

@NgModule({
  declarations: [
    ToolbarComponent // This is where it should be imported.
  ],
  imports: [
    CommonModule, 
    SharedModule,
  ],
  exports: [
    ToolbarComponent // Also here.
  ]
})
export class LayoutModule { }

app.module.ts

@NgModule({
  declarations: [
    AppComponent,
  ],
  imports: [
    BrowserModule,
    AppRoutingModule,
    BrowserAnimationsModule,
    LayoutModule, // Import LayoutModule here.
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

By following this setup, you will have full access to the

<app-toolbar></app-toolbar>

component selector in your app.component.html just by importing LayoutModule.

Answer 7

Answer №4

Whenever you generate a component using the Angular CLI, it is important to note that the component should be automatically included in both the import and decoration sections of the app.module.ts file in your application. If, for some reason, the Angular CLI fails to carry out these tasks after creating the component and you have to manually add it, there may be a risk of duplication leading to errors in the background. Resolution: The issue could potentially stem from either the Angular CLI version or your internet connection, meaning that the Angular CLI might face obstacles in performing certain operations.

Answer 8

Whenever you generate a component using the Angular CLI, it is important to note that the component should be automatically included in both the import and decoration sections of the app.module.ts file in your application. If, for some reason, the Angular CLI fails to carry out these tasks after creating the component and you have to manually add it, there may be a risk of duplication leading to errors in the background. Resolution: The issue could potentially stem from either the Angular CLI version or your internet connection, meaning that the Angular CLI might face obstacles in performing certain operations.

The module has been declared by multiple NgModules

Answer №1

Answer №2

Answer №3

Answer №4

Similar questions

Tips on using class-validator @isArray to handle cases where only a single item is received from a query parameter

Creating a rotating circle in CSS with ion-slides: A step-by-step guide

The JSX component in next.js cannot be utilized as a user component

Angular 16 routing not loading content

Entering _this

Issue encountered while initializing a fresh project with Angular CLI version 13.1.0

Having difficulty implementing NG Zorro into the project because of a dependency issue

Issues with NPM start arise moments after incorporating create react app typescript into the project

Navigating session discrepancies: Combining various social media platforms using Next.js and NextAuth

Adding an icon to the contents of a specific column in Angular material

What is the best way to toggle the Angular date picker on and off for a specific date with Angular Material?

Is it possible to utilize a function within an Angular [routerLink] to define the query parameter?

Incorporating the Vidyard embedded player within an Angular application

Tips and tricks for displaying JSON data in Angular 2.4.10

There was a problem with the module '@angular/material' as it was unable to export a certain member

Generate a unique identifier based on data type

Tips for resolving Typescript type error when overriding MuiContainer classes

Utilizing React and MobX to dynamically render components based on observable arrays

The CSS variables set within the :root section of styles.scss are not recognized as valid

Utilizing Typescript template strings for data inference