[Solved] Why does this Angular component fail to inject the service?@Component({selector: 'app', template: ''}) export class MyComponent { constructor(private dataService:... | Angular

Angular - Services and Dependency Injection

Why does this Angular component fail to inject the service?

@Component({selector: 'app', template: ''})
export class MyComponent {
  constructor(private dataService: DataService) {}
}

Given DataService is not provided anywhere.

ADataService class is missing @Component decorator

BDataService is not registered as a provider

CConstructor parameter is missing private keyword

DComponent selector is incorrect

Step-by-Step Solution

Solution:

Step 1: Check service registration
DataService must be registered as a provider in a module or via providedIn for DI to work.
Step 2: Verify other options
Selector and private keyword are correct; DataService should have @Injectable, not @Component.
Final Answer:
DataService is not registered as a provider -> Option B
Quick Check:
Service must be provided to be injectable [OK]

Quick Trick: Register services as providers or use providedIn [OK]

Common Mistakes:

MISTAKES

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Why does this Angular component fail to inject the service?