feature request: UnwrapCaslSubjectPipe

[ruscon]

If you want to get subject from hook into a class method argument, you need to use SubjectProxy and manually get the subject (example from docs)

@Mutation(() => Post)
@UseGuards(AuthGuard, AccessGuard)
@UseAbility(Actions.update, Post, PostHook)
async updatePost(
  @Args('input') input: UpdatePostInput,
  @CaslSubject() subjectProxy: SubjectProxy<Post>
) {
  const post = await subjectProxy.get();
}

This can be automated through a generic pipe

import { Injectable, NotFoundException, PipeTransform } from '@nestjs/common';
import type { SubjectProxy } from 'nest-casl';

@Injectable()
export class UnwrapCaslSubjectPipe<T> implements PipeTransform<SubjectProxy<T>, Promise<T>> {
    async transform(subjectProxy: SubjectProxy<T>): Promise<T> {
        const subject = await subjectProxy.get();

        if (!subject) {
            throw new NotFoundException();
        }

        return subject;
    }
}

And code will be like this

@Mutation(() => Post)
@UseGuards(AuthGuard, AccessGuard)
@UseAbility(Actions.update, Post, PostHook)
async updatePost(
  @Args('input') input: UpdatePostInput,
  @CaslSubject(UnwrapCaslSubjectPipe) post: Post,
) {
  // do anything with post oject
}

[liquidautumn]

I looked desperately to hide proxy details and never found this solution. Would be so nice to implicitly unwrap proxy, but API already published. Maybe add Subject and alike decorators and deprecate prefixed ones. Anyway, this is super useful, I'll think how to best handle it and add asap.

[ruscon]

There is no BC in my example :)
Just need to add UnwrapCaslSubjectPipe to your library (@CaslSubject works with pipes)

[AlexStansfield]

I'd be interested in something like this.

Basically right now whenever there is an ID for a resource in the parameters we use a transformer pipe so that fetch the resource, error if not found and then have it delievered into the controller method argument.

e.g

  @Get(':id')
  @UseGuards(AccessGuard)
  @UseAbility(Actions.read, ProductDto)
  @ApiOkResponse({ type: ProductDto })
  getProduct(@Param('id', ProductTransformerPipe) product: IProduct): IProduct {
    return product;
  }

Would love a way that Casl could use this object as the subject. Any ideas?