How to handle circular dependencies in NestJS modules?

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How to handle circular dependencies in NestJS modules?

asked about 1 year ago

I have two services in NestJS: UsersService and PostsService. They depend on each other, which causes a circular dependency error when starting the app. What is the best practice to handle this kind of situation in NestJS?

typescript

nestjs

1 Answer

John Doe

• answered about 1 year ago

You can use NestJS's forwardRef function to resolve circular dependencies:

1@Module({
2  providers: [UsersService],
3  imports: [forwardRef(() => PostsModule)],
4  exports: [UsersService],
5})
6export class UsersModule {}

1@Module({
2  providers: [UsersService],
3  imports: [forwardRef(() => PostsModule)],
4  exports: [UsersService],
5})
6export class UsersModule {}

And inside PostsModule, do the same:

1@Module({
2  providers: [PostsService],
3  imports: [forwardRef(() => UsersModule)],
4  exports: [PostsService],
5})
6export class PostsModule {}

1@Module({
2  providers: [PostsService],
3  imports: [forwardRef(() => UsersModule)],
4  exports: [PostsService],
5})
6export class PostsModule {}

This tells NestJS to resolve the modules later, preventing the circular import from crashing the app.

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