Nest: How rewrite service exception?

Created on 6 Nov 2017 · 7Comments · Source: nestjs/nest

Hi all, i can't rewrite controllers exceptions.
When TypeORM generate some exceptions, i want display this for end user in error message.
Exception Filters and Interceptors not work in this case.

question 🙌

Source

xvs32x

Most helpful comment

I haven't used Observable a much. Maybe something like this could work:

create = (user: UserDto): Observable<User> => Observable
        .fromPromise(this.userRepository.save({ ...new User(), ...user }))
.catch((err) => Observable.throw(mapBusinessError(err));

Matonen on 6 Nov 2017

👍3

All 7 comments

It would better to catch TypeORM exceptions in service level and transform those business exceptions which are then handled in controller level. Then you can catch those using filters and send maybe Bad Request back to clients.

Matonen on 6 Nov 2017

@Matonen Thank for yout help. How i can tranfrom this exception? For example i have user.service with create method:

create = (user: UserDto): Observable<User> => Observable
        .fromPromise(this.userRepository.save({ ...new User(), ...user }))

and controller method

    @Post('create')
    async create( @Body() user: UserDto) {
        return this.userService.create(user);
    }

xvs32x on 6 Nov 2017

I haven't used Observable a much. Maybe something like this could work:

create = (user: UserDto): Observable<User> => Observable
        .fromPromise(this.userRepository.save({ ...new User(), ...user }))
.catch((err) => Observable.throw(mapBusinessError(err));

Matonen on 6 Nov 2017

👍3

@Matonen thank you, after mapping work is nice, my example:

 create = (user: UserDto): Observable<User> => Observable
        .fromPromise(this.userRepository.save({ ...new User(), ...user }))
        .catch(err => Observable.throw(new HttpException(err.sqlMessage, 500)))

xvs32x on 7 Nov 2017

Great! Also think about extends HttpException with your custom ones to have better readability.

I dont't know what kind app you are writing but it not usually good idea to send sql error message back to client.

Matonen on 7 Nov 2017

👍1

Hi @xvs32x,
Yeah, @Matonen solution is great! Glad you found an answer 🙂