Catch

Kind: Function

Source: packages/common/decorators/core/catch.decorator.ts

Part of: Common

Decorator that marks a class as a Nest exception filter. An exception filter handles exceptions thrown by or not handled by your application code.

The decorated class must implement the ExceptionFilter interface.

Catch() marks a class as a Nest exception filter, allowing it to intercept exceptions thrown during request processing. The decorated class must implement Nest's ExceptionFilter interface and can optionally target one or more specific exception types.

Signature

ts
function Catch(exceptions: Array<Type<any> | Abstract<any>>): ClassDecorator

Parameters

Name	Type
`exceptions`	`Array<Type

Returns: ClassDecorator

Diagram

mermaid
graph LR
  A[Request Handler] -->|throws exception| B[Nest Exception Layer]
  B --> C{Matching @Catch Filter?}
  C -->|Yes| D[Custom ExceptionFilter.catch]
  D --> E[Create HTTP Response]
  C -->|No| F[Default Nest Exception Handler]

Usage

ts
import {
  ArgumentsHost,
  Catch,
  ExceptionFilter,
  HttpException,
} from '@nestjs/common';

@Catch(HttpException)
export class HttpExceptionFilter implements ExceptionFilter {
  catch(exception: HttpException, host: ArgumentsHost): void {
    const response = host.switchToHttp().getResponse();
    const request = host.switchToHttp().getRequest();

    response.status(exception.getStatus()).json({
      statusCode: exception.getStatus(),
      path: request.url,
      message: exception.message,
    });
  }
}

// Register globally:
// app.useGlobalFilters(new HttpExceptionFilter());

AI Coding Instructions

Decorate exception filter classes with @Catch(); pass exception constructors such as HttpException to handle only matching errors.
Always implement the ExceptionFilter interface and provide a catch(exception, host) method.
Use ArgumentsHost to select the active transport context, such as host.switchToHttp() for HTTP requests.
Register filters globally with app.useGlobalFilters(), at controller scope with @UseFilters(), or provide them through Nest dependency injection.
Avoid swallowing exceptions without sending or delegating an appropriate response for the active transport.

Used by

6 references from 6 files. Each is a place in this repository where the symbol is actually used — go read one rather than trusting an example.

Imported by (6)

UnauthorizedFilter — integration/graphql-code-first/src/common/filters/unauthorized.filter.ts:4
HttpExceptionFilter — integration/inspector/src/common/filters/http-exception.filter.ts:8
RequestFilter — integration/websockets/src/request.filter.ts:4
HttpExceptionFilter — sample/01-cats-app/src/common/filters/http-exception.filter.ts:8
ExceptionFilter — sample/03-microservices/src/common/filters/rpc-exception.filter.ts:5
HttpExceptionFilter — sample/36-hmr-esm/src/common/filters/http-exception.filter.ts:8