The AppModule has imported an unexpected value of '[object Object]', causing errors

Question

The AppModule has imported an unexpected value of '[object Object]', causing errors

How can I properly import the Pipe Module into my Angular app?

import { NgModule } from '@angular/core';
import { PipeTransform, Pipe } from '@angular/core';

@Pipe({ name: 'values',  pure: false })
export class CustomPipe implements PipeTransform {
  transform(value: any, args: any[] = null): any {
    return Object.keys(value).map(key => value[key]);
  }

  static forRoot() {
      return {
          ngModule: CustomPipe,
          providers: [],
      };
   }
}

This is my custom pipe module.

In my app.module.ts

imports: [
   ...,
    CustomPipe.forRoot()

However, when I import it like this, I encounter the following error:

Unexpected value '[object Object]' imported by the module 'AppModule'

angular typescript module

Answer 1

Answer №1

I encountered a similar error, although the root cause was completely different.

Even though my solution may not be relevant to the original question, I am sharing it here just in case it can help someone facing a similar issue:

During my unit tests, I mistakenly defined a provider object within the imports array instead of the correct providers array. This misplacement was what led to the error.

Answer 2

I encountered a similar error, although the root cause was completely different.

Even though my solution may not be relevant to the original question, I am sharing it here just in case it can help someone facing a similar issue:

During my unit tests, I mistakenly defined a provider object within the imports array instead of the correct providers array. This misplacement was what led to the error.

Answer 3

Answer №2

The class called PipeModule needs to be decorated with the @NgModule decorator in order to be considered a module. Without this decorator, it cannot be imported into your main AppModule, as only classes with the @NgModule decorator are allowed to be imported.

In the context of creating an Angular pipe, it is recommended to rename the class from PipeModule to something like ValuesPipe to avoid confusion and make the purpose clear.

Once you have renamed your class to ValuesPipe, you have two options: either declare ValuesPipe directly in the AppModule, or create a separate NgModule specifically for ValuesPipe and then import that new module into your main AppModule.

Assuming you have renamed the class to ValuesPipe in your code examples:

Option 1:

In app.module.ts,

declarations: [
  .....,
  ValuesPipe,
]

Or Option 2:

Create a new class called PipeModule as shown below:

@NgModule({
   imports: CommonModule,  (from @angular/core)
   declarations: ValuesPipe,
})
export class PipeModule { }

Then, in app.module.ts,

imports: [
  ......,
  PipeModule
]

Answer 4

The class called PipeModule needs to be decorated with the @NgModule decorator in order to be considered a module. Without this decorator, it cannot be imported into your main AppModule, as only classes with the @NgModule decorator are allowed to be imported.

In the context of creating an Angular pipe, it is recommended to rename the class from PipeModule to something like ValuesPipe to avoid confusion and make the purpose clear.

Once you have renamed your class to ValuesPipe, you have two options: either declare ValuesPipe directly in the AppModule, or create a separate NgModule specifically for ValuesPipe and then import that new module into your main AppModule.

Assuming you have renamed the class to ValuesPipe in your code examples:

Option 1:

In app.module.ts,

declarations: [
  .....,
  ValuesPipe,
]

Or Option 2:

Create a new class called PipeModule as shown below:

@NgModule({
   imports: CommonModule,  (from @angular/core)
   declarations: ValuesPipe,
})
export class PipeModule { }

Then, in app.module.ts,

imports: [
  ......,
  PipeModule
]

The AppModule has imported an unexpected value of '[object Object]', causing errors

Answer №1

Answer №2

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