In nestjs, how can we change default error messages from typeORM globally? - nestjs

Question

I have this code to change the default message from typeorm when a value in a unique column already exists. It just creates a custom message when we get an error 23505.
if (error.code === '23505') {
// message = This COLUMN VALUE already exists.
const message = error.detail.replace(
/^Key \((.*)\)=\((.*)\) (.*)/,
'The $1 $2 already exists.',
);
throw new BadRequestException(message);
}
throw new InternalServerErrorException();
I will have to use it in other services, so I would like to abstract that code.
I think I could just create a helper and then I import and call it wherever I need it. But I don’t know if there is a better solution to use it globally with a filter or an interceptor, so I don’t have to even import and call it in different services.
Is this possible? how can that be done?
If it is not possible, what do you think the best solution would be?
Here all the service code:
#Injectable()
export class MerchantsService {
constructor(
#InjectRepository(Merchant)
private merchantRepository: Repository<Merchant>,
) {}
public async create(createMerchantDto: CreateMerchantDto) {
try {
const user = this.merchantRepository.create({
...createMerchantDto,
documentType: DocumentType.NIT,
isActive: false,
});
await this.merchantRepository.save(user);
const { password, ...merchantData } = createMerchantDto;
return {
...merchantData,
};
} catch (error) {
if (error.code === '23505') {
// message = This COLUMN VALUE already exists.
const message = error.detail.replace(
/^Key \((.*)\)=\((.*)\) (.*)/,
'The $1 $2 already exists.',
);
throw new BadRequestException(message);
}
throw new InternalServerErrorException();
}
}
public async findOneByEmail(email: string): Promise<Merchant | null> {
return this.merchantRepository.findOneBy({ email });
}
}

Answer 1

I created an exception filter for typeORM errors.
This was the result:
import {
ArgumentsHost,
Catch,
ExceptionFilter,
HttpStatus,
InternalServerErrorException,
} from '#nestjs/common';
import { Response } from 'express';
import { QueryFailedError, TypeORMError } from 'typeorm';
type ExceptionResponse = {
statusCode: number;
message: string;
};
#Catch(TypeORMError, QueryFailedError)
export class TypeORMExceptionFilter implements ExceptionFilter {
private defaultExceptionResponse: ExceptionResponse =
new InternalServerErrorException().getResponse() as ExceptionResponse;
private exceptionResponse: ExceptionResponse = this.defaultExceptionResponse;
catch(exception: TypeORMError | QueryFailedError, host: ArgumentsHost) {
const ctx = host.switchToHttp();
const response = ctx.getResponse<Response>();
exception instanceof QueryFailedError &&
this.setQueryFailedErrorResponse(exception);
response
.status(this.exceptionResponse.statusCode)
.json(this.exceptionResponse);
}
private setQueryFailedErrorResponse(exception: QueryFailedError): void {
const error = exception.driverError;
if (error.code === '23505') {
const message = error.detail.replace(
/^Key \((.*)\)=\((.*)\) (.*)/,
'The $1 $2 already exists.',
);
this.exceptionResponse = {
statusCode: HttpStatus.BAD_REQUEST,
message,
};
}
// Other error codes can be handled here
}
// Add more methods here to set a different response for any other typeORM error, if needed.
// All typeORM erros: https://github.com/typeorm/typeorm/tree/master/src/error
}
I set it globally:
import { TypeORMExceptionFilter } from './common';
async function bootstrap() {
//...Other code
app.useGlobalFilters(new TypeORMExceptionFilter());
//...Other code
await app.listen(3000);
}
bootstrap();
And now I don't have to add any code when doing changes in the database:
#Injectable()
export class MerchantsService {
constructor(
#InjectRepository(Merchant)
private merchantRepository: Repository<Merchant>,
) {}
public async create(createMerchantDto: CreateMerchantDto) {
const user = this.merchantRepository.create({
...createMerchantDto,
documentType: DocumentType.NIT,
isActive: false,
});
await this.merchantRepository.save(user);
const { password, ...merchantData } = createMerchantDto;
return {
...merchantData,
};
}
}
Notice that now I don't use try catch because nest is handling the exceptions. When the repository save() method returns an error (actually it is a rejected promise), it is caught in the filter.