CODEWITHSUNDEEP
javascripttypescriptnestjs
Noor_Hasan
Noor_Hasan

Reputation: 97

How can I use forwardRef() for circular dependency?

How can I use forwardRef() for circular dependency? I did the same as the documentation but didn't work it gives me this error: The module at index [1] of the GroupModule "imports" array is undefined.

Potential causes:

Scope [AppModule -> EntityModule -> BranchModule] +91ms

Upvotes: 2

Views: 3271

Answers (1)

Noor_Hasan
Noor_Hasan

Reputation: 97

the circular dependency happened when two modules are calling each other, for example, if I have an animal module and a cats model calling each other:

in animal.module.ts:

import { forwardRef, Module } from '@nestjs/common';
import { AnimalController } from './animal.controller';
import { AnimalService }    from './animal.service';
import { AnimalRepository } from './animal.repository';

@Module({
    imports: [
        forwardRef(() => CatModule),
        
    ],
    controllers: [AnimalController],
    providers  : [AnimalService, AnimalRepository],
    exports    : [AnimalService],
})
export class AnimalModule { }

in cat.module.ts:

import { forwardRef, Module } from '@nestjs/common';
import {CatController } from './cat.controller';
import { CatService }    from './cat.service';
import { CatRepository } from './cat.repository';

@Module({
    imports: [
        forwardRef(() => AnimalModule),
        
    ],
    controllers: [CatController],
    providers  : [CatService, CatRepository],
    exports    : [CatService],
})
export class CatModule { }

in animal.service.ts:

export class AnimalService {

constructor(
   
    @Inject(forwardRef(() => CatService)) private readonly catService: CatService,
   

) {
   
}//rest of code here}

in cat.service.ts:

export class CatService {

constructor(

    @Inject(forwardRef(() => AnimalService)) private readonly animalService: AnimalService,


) {

}//rest of code here}

Upvotes: 2

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