I've got a PlayersModule and an ItemsModule.
I want to use the ItemsService in the PlayersService.
When I add it by injection:
import { Injectable } from '#nestjs/common';
import { InjectModel } from 'nestjs-typegoose';
import { ModelType, Ref } from 'typegoose';
import { Player } from './player.model';
import { Item } from '../items/item.model';
import { ItemsService } from '../items/items.service';
#Injectable()
export class PlayersService {
constructor(
#InjectModel(Player) private readonly playerModel: ModelType<Player>,
private readonly itemsService: ItemsService){}
I get this nest error :
[Nest] 11592 - 2018-8-13 11:42:17 [ExceptionHandler] Nest can't
resolve dependencies of the PlayersService (+, ?). Please make sure
that the argument at index [1] is available in the current context.
Both modules are imported in the app.module.ts. Both services are working alone in their module.
You have to export the ItemsService in the module that provides it:
#Module({
controllers: [ItemsController],
providers: [ItemsService],
exports: [ItemsService]
^^^^^^^^^^^^^^^^^^^^^^^
})
export class ItemsModule {}
and then import the exporting module in the module that uses the service:
#Module({
controllers: [PlayersController],
providers: [PlayersService],
imports: [ItemsModule]
^^^^^^^^^^^^^^^^^^^^^^
})
export class PlayersModule {}
⚠️ Don't add the same provider to multiple modules. Export the provider, import the module. ⚠️
Let' say you want to use AuthService from AuthModule in my TaskModule's controller
for that, you need to export authService from AuthModule
#Module({
imports: [
....
],
providers: [AuthService],
controllers: [AuthController],
exports:[AuthService]
})
export class AuthModule {}
then in TaskModule, you need to import AuthModule (note: import AuthModule not the AuthService in TaskModule)
#Module({
imports:[
AuthModule
],
controllers: [TasksController],
providers: [TasksService]
})
export class TasksModule {}
Now you should be able to use DI in TaskController
#Controller('tasks')
export class TasksController {
constructor(private authService: AuthService) {}
...
}
The question is answered by Kim Kern. But I just want to remind people who read through this comment. Whenever you get this error, you should follow these steps that may help you easily figure out where the stuck is:
Make sure the Module which provides providers was imported.
Make sure the provider which you are using is exported.
For example, you have category module which contains category service, post module has post service and it has category service as a dependency:
#Module({
controllers: [CategoryController],
providers: [CategoryService],
exports: [CategoryService] // Remember to export
})
export class CategoryModule {}
And
#Module({
imports: [CategoryModule], // Make sure you imported the module you are using
controllers: [PostController],
providers: [PostService]
})
export class PostModule {}
Don't forget to use this annotation.
Nest uses this to detect singleton class.
In spring boot - Java, this one used to be called Bean. Read more:
#Injectable()
export class PostService {
constructor(private readonly categoryService: CategoryService // This will be auto injected by Nestjs Injector) {}
}
I solved my problem by removing #Inject() from the argument in my constructor that was passing the exported service.
I believe that you faced the same problem i had. My scenario was 2 sibling custom modules (user, auth) that needed to use each other's services. I used circular DI to solve it. please check this link
Let me know whether if it solved your issue, maybe I can advise you further.
Solved my problem by changing the way of importing the constant string (TOKEN) used in #Inject()) of my provider... be careful using index.ts whith export * from module.ts, nest won't resolve the dependecy
Based on the answer by Kim Kern nowadays we should add only injected service into our service without any decorators (#Inject() doesn't required). After that it will work right. That was my mistake and probably can help others.
Steps 1. Export the file that you want
Step 2. Import the whole module.
I initially made a mistake of adding the file as provider and also adding the module which was throwing error.
Related
I'm trying to use nest custom provider with factory, for some reason I'm struggling to get it working.
I've created the following sample -
interface ProviderOptions: {x:string, y:number};
interface AsyncProps {useFactory:(...args:any[])=> ProviderOptions, inject:any[], imports:any[] }
#Module({})
export class MyModule {
static forRootAsync(asyncProps: AsyncProps): DynamicModule {
const myFactory: Provider = {
provide: "MY_PROVIDER",
useFactory: asyncProps.useFactory,
inject: asyncProps.inject,
};
return {
module: MyModule,
providers: [myFactory, MyService],
exports: [MyService],
imports: [...asyncProps.imports],
};
}
}
#Injectable()
export class MyService {
constructor(#Inject("MY_PROVIDER") this options:ProviderOptions){
}
}
For some reason I'm unable to resolve MyService -
Error: Nest can't resolve dependencies of the MyService (?). Please
make sure that the argument dependency at index [0] is available in
the MyModule context.
what I'm missing here?
Thanks!
UPDATE -
so now it's really strange -
originally MyService was in a different file, next to MyModule. when moved MyService to the same file as MyModule, the above code does work as expected. how can it be?
Based on your error, you have a circular file import which means that typecript can't resolve the class name and in turn Nest can't create the class. I just answered another question on it here
I have the following scenario in NestJS:
// user.service.ts
#Injectable()
export class UserService {
constructor(
private readonly userRepository: UserRepository,
private readonly userProfileService: UserProfileService,
) {}
}
// user-profile.service.ts
#Injectable()
export class UserProfileService {
constructor(
private readonly userProfileRepository: UserProfileRepository,
) {}
}
// user.module.ts
#Module({
imports: [DataRepositoryModule], // Required for the repository dependencies
providers: [UserService, UserProfileService],
exports: [UserService, UserProfileService],
})
export class UserModule {}
However, when I try to use the UserService inside a controller from another module, I get the following error:
Nest can't resolve dependencies of the UserService (UserRepository, ?). Please make sure that the argument dependency at index [1] is available in the UserModule context.
Potential solutions:
- If dependency is a provider, is it part of the current UserModule?
- If dependency is exported from a separate #Module, is that module imported within UserModule?
#Module({
imports: [ /* the Module containing dependency */ ]
})
Controller code:
#Controller()
export class UserController {
constructor(private readonly userService: UserService) {}
}
Controller module:
#Module({
imports: [],
providers: [],
controllers: [UserController],
})
export class UserManagementModule {}
Main app.module.ts:
#Module({
imports: [
UserManagementModule,
UserModule,
DataRepositoryModule.forRoot(),
],
controllers: [],
providers: [],
})
export class AppModule {}
I'm confused because I'm doing exactly what the error suggests, adding both services inside the providers array (UserModule). What could I be missing?
From your error, it looks like there's a circular dependency between your file imports. Check to make sure that you don't have a circular import chain going on (i.e. ServiceA imports ServiceB imports ServiceA or ServiceA imports ModuleA imports ServiceB imports ServiceA). This can especially become common common when using barrel files inside the same module.
Bug Report
Current behavior
Getting error while instantiating the PaymentProcessorModule:
Error: Nest can't resolve dependencies of the PaymentProcessor (?, PaymentsService, ProcessingService). Please make sure that the argument TransactionsService at index [0] is available in the PaymentProcessor context.
Potential solutions:
- If TransactionsService is a provider, is it part of the current PaymentProcessor?
- If TransactionsService is exported from a separate #Module, is that module imported within PaymentProcessor?
#Module({
imports: [ /* the Module containing TransactionsService */ ]
})
However, both services come from the same module.
Input Code
Here's my module:
#Module({
imports: [
TypeOrmModule.forFeature([ Transaction ]),
],
providers: [
PaymentProcessor,
TransactionsService,
TransactionsResolver,
],
exports: [PaymentProcessor],
})
export class PaymentProcessorModule {}
TransactionService:
#Injectable()
export class TransactionsService {
constructor(
#InjectRepository(Transaction) private transRepo: Repository<Transaction>,
) {}
//...
}
And finally, PaymentProcessor:
#Injectable()
export class PaymentProcessor {
constructor(
private transactions: TransactionsService,
private payments: PaymentsService,
private processor: ProcessingService,
) {}
//...
}
Expected behavior
Expected to inject the TransactionsService. I could not seem to reproduce it in a sample repo, unfortunately.
Environment
Nest version: 7.4.1
The official support of NestJS told me that the PaymentProcessor must be mentioned in the imports array somewhere. I checked for usages of the class and it's true, I accidentally imported the provider instead of the module in another context.
I am developing an angular library. it has an internal service. which is defined like below.
Used providedIn to be tree-shakable. and didn't use providedIn:'root' because its internal and just used in the module scope.
#Injectable({
providedIn: MyChartModule,
})
export class LineChartLibService {
and when i wanted to add forRoot in module definition to have just one instance in lazy loading, it encounter Circular dependency.
export class MyChartModule {
static forRoot(): ModuleWithProviders {
return {
ngModule: MyChartModule,
providers: [LineChartLibService],
};
}
}
what should we do in this situations?
is it possible to have a lazy load-able tree-shakable service in library?
WARNING: Circular dependency: dist\my-chart\esm2015\lib\my-chart.module.js -> dist\my-chart\esm2015\lib\line-chart\line-chart.component.js
-> dist\my-chart\esm2015\lib\line-chart-lib.service.js -> dist\my-chart\esm2015\lib\my-chart.module.js
I have previously answered a (non-duplicate) question that provides you with alternatives to this approach.
https://stackoverflow.com/a/60377431/5367916
Take this setup:
my-module.ts
declarations: [
MyComponent
]
my-service.ts
#Injectable({ providedIn: MyModule })
my-component.ts
constructor(private myService: MyService) {}
my-service imports my-module
my-module imports my-component
my-component imports my-service
There is a circular dependency.
A workaround
The workaround for this is to create a service module and import that into your module.
my-module.ts
imports: [
MyModuleServices
],
declarations: [
MyComponent
]
my-module-services.ts
// no imports or declarations
my-service.ts
#Injectable({ providedIn: MyModuleServices })
my-component.ts
constructor(private myService: MyService) {}
Alternative
The much more straightforward way is to add the service to your module's providers.
#NgModule({
providers: [ MyService ]
})
export class MyModule {}
I think what happens is the following:
You have the line-chart.component.js that probably calls for the LineChartLibService.
Within the LineChartLibService you say that this Injectable is provided in MyChartModule.
Within the MyChartModule you probably declare the line-chart.component.js to be part of this module.
This means the module asks for the component, which asks for the service, which asks for the module which then asks for the component again: A circular dependency.
If you add more code and context to your question, we might be able to make a better suggestion ;-)
I have an Angular service that looks like this
#Component({})
#Inject(ChromeDataService)
#Injectable()
export class MainDataService {
}
when I run ng build --prod, I get this error
ERROR in : No template specified for component MainDataService
my only guess is that an Angular service does not need to be a component? So I removed the #Component annotation, but then I get this:
ERROR in : Unexpected value 'MainDataService in
/home/.../main.ts'
declared by the module 'SharedModule in
/home/.../src/app/shared.module.ts'.
Please add a #Pipe/#Directive/#Component annotation.
Uh, how do I create a service in Angular5?
To use an angular service properly you only need injectable()
Here's an example
#Injectable()
export class myService {
//some logic
}
then in your app.module or in a feature module you add the service in the providers array and to have the angular DI handle the service for you.
#Component({
usual stuff with template, selector, css})
export class someComponent {
constructor(private myService: MyService){}
}
The constructor will tell angular to auto-magically inject the service you need in.
your service only needs the #Injectable() decorator.like this
import {Injectable} from '#angular/core'
import {Router} from '#angular/router'
#Injectable()
export class AuthService {
constructor(private router: Router) {}
}
That's how I declare services in Angular:
#Injectable()
export class AuthService {
...
}
I think you only need #Injectable decorator. Maybe your problem comes from shared.module.ts.