I am running into issues getting the proper class injected with NestJS. There is a base class #Injectable() export class FakeBinanceClient implements ITradeClient {... and a child class #Injectable() export class ScheduledFakeBinanceClient extends FakeBinanceClient {...
I do inject the child explicitely in another class by constructor(#Inject(ScheduledFakeBinanceClient) tradeClient: ITradeClient, .... However, the FakeBinanceClient base class gets injected.
The main module also states clearly to use the child class:
#Module({
imports: [
...
],
controllers: [],
providers: [ScheduledFakeBinanceClient, ... (no FakeBinanceClient)]
})
export class AppModule {}
Any idea whe the child class isn't being injected?
Wasn't a code problem. I simply had to delete the dist-folder and rebuild.
Related
I already checked the link NestJs dependency injection with task scheduling is not working but that is not the same problem that I have since I'm not using request scope on the on my injectable service.
I recorded a loom video to show the issue.
https://www.loom.com/share/37875a6e0d79400698a4408ef8d9ac89
Thanks
Tiago
Solved. Thanks to #Micael Levi.
The problem was the provider array on AppModule. It was instantiating the ReckonService again.
Example of the ReckonModule after fix:
#Module({
imports: [HttpModule],
controllers: [ReckonController],
providers: [ReckonService],
exports: [ReckonService],
})
export class ReckonModule {}
Example of the AppModule after fix:
#Module({
imports: [ReckonModule],
controllers: [],
providers: [AppService],
})
export class AppModule {}
Thanks
Tiago
Current behavior
The documentation states here that:
...we passed the RolesGuard type (instead of an instance), leaving responsibility for instantiation to the framework and enabling dependency injection.
So I'm expecting to "override" a guard with another, via the module's providers.
This doesn't work as expected.
Interestingly enough,
injecting the same service via the controller's constructor does yield the correct service, though.
Input Code
Simple: https://github.com/dima-gusyatiner/nestjs-guards-override/tree/only-app-module
With Another module, using exports: https://github.com/dima-gusyatiner/nestjs-guards-override/tree/master
Controller:
#Controller()
#UseGuards(AuthGuard)
Module:
#Module({
controllers: [AppController],
providers: [
{
provide: AuthGuard,
useClass: AuthOverrideGuard,
}
],
})
Expected behavior
I would expect AuthGuard to never even be constructed.
Instead, both classes are constructed, and AuthGuard is used as the guard.
Environment
- Nest version: 8.0.6
- Node version: 16.8.0
- Platform: Linux
Bug Report
I've also opened a ticket for this:
https://github.com/nestjs/nest/issues/8011
Question
Am I doing something wrong here, or is this a bug?
Anybody can suggest a workaround?
I am not sure I understand it that well either but from what I saw:
With UseGuards, the passed in class is not resolved as provider. Only when you declare the guard as a dependency. Just like in AppController, is it looked up in the provider scope.
Sure the guard's dependencies are resolved as providers within the calling module's scope but it itself is not. Just regular instantiation with dependency injection.
I think that is why both guards are still created, just that AuthOverrideGuard, is registered as a provider.
That is why you get the following output:
[Nest] 77074 - 05/09/2021, 05:01:39 LOG [NestFactory] Starting Nest application...
Construct AuthOverrideGuard
Construct AuthGuard
AuthGuard
AppController AuthOverrideGuard {}
This is why this.guard is correctly resolved as AuthOverrideGuard from the provider scope
To summarize, in my understanding, the docs are inaccurate.
The documentation states here that:
...we passed the RolesGuard type (instead of an instance), leaving responsibility for instantiation to the framework and enabling dependency injection.
This is inaccurate, since RolesGuard won't be instantiated with proper dependency injection. Instead, it will be instantiated using this exact class only.
To achieve proper dependency injection, one should use another class, injected via the guard's constructor. For example:
import { CanActivate, ExecutionContext, Injectable } from '#nestjs/common';
import { Observable } from 'rxjs';
import { AuthService } from '../services';
#Injectable()
export class AuthGuard implements CanActivate {
constructor(
private readonly auth: AuthService,
) {}
canActivate(context: ExecutionContext) {
return this.auth.canActivate(context);
}
}
You can never provide another AuthGuard, it won't work. But you can provide another AuthService, which this guard uses.
#Module({
controllers: [AppController],
providers: [
{
provide: AuthService,
useClass: AuthServiceOverride,
}
],
})
I have a component which contains a generic popup, it implements therefore the interface PopupParent
#Injectable()
#Component(
//...
)
class SubjectListComponent implements OnInit, PopupParent {
}
The generic class InfoPopup needs to deal abstractly with its parent (that implements PopupParent), so I would like to take get the parent injected by its interface (instead of being injected by its concrete class SubjectListComponent)
class InfoPopup {
final PopupParent _parent;
InfoPopup(this._parent);
//...non relevant code
}
The issue is that the SubjectListComponent was registred by class in the injector, so the injector won't find what to inject into the InfoPopup class.
If I try to declare my SubjectListComponent manually, I found that it has to be done in the providers constants. but I still don't have my instance of SubjectListComponent when I declare my component...
How could I do that?
I also tried to pass the parent to an #Input:
#Component(
selector: 'info-popup',
templateUrl: 'info_popup.html',
styleUrls: const ['info_popup.css'],
)
class InfoPopup {
#Input()
final PopupParent parent;
InfoPopup(this._parent);
//...non relevant code
}
But then I got stuck on how to inject the this instance from the component client :
subject_list_comp.html:
<div>
<info-popup [parent]="this"></info-popup>
</div>
since dart angular doesn't recognize this as a keyword, but it searches for a property called this in SubjectListComponent.dart
Two issues were created for this question:
https://github.com/dart-lang/site-webdev/issues/514
https://github.com/dart-lang/site-webdev/issues/515
This can be accomplished by providing aliases. multi: true allows to add more than one alias. There is no way to make automatically derive the interfaces.
#Component(
providers: [
const Provider(PopupParent, useExisting: SubjectListComponent, multi: true),
const Provider(PopupParent, useExisting: FooComponent, multi: true)
]
)
class InfoPoupup ...
update
To make
[parent]="this"
work, you could add a getter to the component
get self => this;
and then use
[parent]="self"
I have problem with injecting singleton service into a directive.
I have service:
#Injectable()
export class AuthService{ ... }
I put it into bootstrapper.
bootstrap(AppComponent, [AuthService, ...]);
I made directive, that protects my component:
#Directive({
selector: '[protected]'
})
export class ProtectedDirective {
constructor(private authService:AuthService) { ... }
}
... and added to one of components
#Component({
selector: 'dashboard',
directives: [ProtectedDirective],
template: '<div protected></div',
})
export class DashboardCmp { }
In console i see an error:
ORIGINAL EXCEPTION: No provider for AuthService!
If I add a provider to DashboardCmp, everything works fine, but it's not a singleton service. I set its properties in other component and I don't see them when I'm in directive.
I resolved my problem. Everything was fine but
import {AuthService} from '../services/auth.service'; (in protected.directive.ts)
is not equal to
import {AuthService} from '../Services/auth.service'; ( in main.ts)
Yes, it's stupid, but it made the dependency injection impossible.
I have a NavBar Component which loads the QApi Service, the QApi Service loads the UserService, but I get the following error:
EXCEPTION: No provider for UserService! (NavBarComponent -> QApi -> UserService)
Either I simply don't get the concept of dependency injection, I made a stupid error, or this is just way to complicated compared to native development... Thanks for your help.
Here my code:
UserService:
import {Injectable} from 'angular2/core';
//import {User} from '../data-source-mocks/users';
#Injectable()
export class UserService {
public isAuthenticated = true;
}
QApi Service:
import {Injectable} from 'angular2/core';
import {UserService} from '../user/user.service';
#Injectable()
export class QApi {
constructor(private _userService: UserService) {}
}
NavBar Component:
import {Component} from 'angular2/core';
import {QApi} from '../../services/q-api/q-api';
#Component({
selector: 'nav-bar',
template: `Test NavBar`,
providers: [QApi]
})
export class NavBarComponent {
private _isAuthenticated = false;
constructor(private _QApi: QApi) {}
}
EDIT:
First of all: Thanks for alle the great answers each and every single one helped me to understand dependency injection better, especially this article: https://angular.io/docs/ts/latest/guide/hierarchical-dependency-injection.html
I changed my QApi class to this:
import {Injectable, Inject, Injector} from 'angular2/core';
import {UserService} from '../user/user.service';
import {CardService} from '../card/card.service';
#Injectable()
export class QApi {
constructor() {
var _injector = Injector.resolveAndCreate([UserService,
CardService]);
this.userService = _injector.get(UserService);
this.cardService = _injector.get(CardService);
}
}
Now it works like I hoped it would. Cant thank you guys enough!!
Add UserService to the component providers:
#Component({
selector: 'nav-bar',
template: `Test NavBar`,
providers: [QApi, UserService] // <- add UserService here
})
export class NavBarComponent { /* ... */ }
Here are two good articles to better understand Angular2 Dependency Injection:
blog.thoughtram.io: Dependency Injection in Angular2
blog.thoughtram.io: Injecting services in services in Angular 2
In fact both previous responses are true! ;-)
You need to define the services:
Application level. Within the second parameter of the bootstrap function. It contains the list of the providers that are available for the whole application.
bootstrap(App, [UserService, QApi, ...]);
Component level. Within the providers attribute of the Component annotation. In this case, this is only configured for this component and you need to define this for each component where the QApi service.
#Component({
selector: 'nav-bar',
template: `Test NavBar`,
providers: [QApi, UserService]
})
You also mix things. I mean you can put the UserService provider at the application level and QApi at the component level. In fact what is important is that Angular can find providers for all the involved elements in the processing chaining (with dependency injection). They can come from either component level (1st) or application level (2nd).
Hope that it gives you some additional hints following alexpods and MichaelOryl great answers ;-)
Thierry
List the services in your bootstrap call (wherever you are handling that). Something like the following should work:
bootstrap(App, [UserService, QApi, COMMON_DIRECTIVES, ROUTER_DIRECTIVES, ROUTER_PROVIDERS, HTTP_PROVIDERS]);
providers// directives added here are available to all children
Then you will have a single instance of each of those services available to the rest of your application.