[Solved] Why does this middleware cause a runtime error? @Injectable() export class SampleMiddleware implements NestMiddleware { use(req: Request, res: Response) { console.log('Middleware running'); } } | NestJS

NestJS - Middleware

Why does this middleware cause a runtime error?

@Injectable()
export class SampleMiddleware implements NestMiddleware {
  use(req: Request, res: Response) {
    console.log('Middleware running');
  }
}

AIncorrect class name

BMissing next parameter in use() method

CMissing @Controller decorator

Duse() method should be async

Step-by-Step Solution

Solution:

Step 1: Check method signature
Middleware use() method must accept three parameters: req, res, and next.
Step 2: Identify missing parameter
The next parameter is missing, causing runtime errors when next() is called internally.
Final Answer:
Missing next parameter in use() method -> Option B
Quick Check:
use() needs req, res, next parameters [OK]

Quick Trick: Middleware use() must have three parameters: req, res, next [OK]

Common Mistakes:

Omitting next parameter
Confusing middleware with controllers
Assuming async is required

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Why does this middleware cause a runtime error?

Step 1: Check method signature

Step 2: Identify missing parameter

Final Answer:

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