Linting error (@typescript-eslint/unbound-method)

[ericvoshall]

I keep getting a @typescript-eslint/unbound-method when I attempt to destructure the build result of my ability builder in my project. I am using @casl/ability@6.5.0. Here's my ability builder file:

import {
  AbilityBuilder,
  createMongoAbility,
  MongoAbility,
} from '@casl/ability';
import { Role } from '@prisma/client';
import { z } from 'zod';
import { User } from '@/lib/zod/next-auth';
import { RoleType } from '@/lib/zod/prisma/generated';

export enum Action {
  MANAGE = 'manage',
  CREATE = 'create',
  DELETE = 'delete',
  READ = 'read',
  READ_SENSITIVE = 'read_sensitive',
  UPDATE = 'update',
}
export const ActionSchema = z.nativeEnum(Action);

export enum Subject {
  ALL = 'all',
  APPLICATION = 'application',
  CLIENT = 'client',
  CONTACT = 'contact',
  USER = 'user',
}
export const SubjectSchema = z.nativeEnum(Subject);

export type AppAbility = MongoAbility<[Action, Subject]>;
export type ActionAndSubject = z.infer<typeof ActionAndSubjectSchema>;
export const ActionAndSubjectSchema = z.object({
  action: ActionSchema,
  subject: SubjectSchema,
});

const userHasRole = (user: User, role: RoleType) => {
  return user.roles.includes(role);
};

export const defineAbilityFor = (user?: User) => {
  const { can, build } = new AbilityBuilder<AppAbility>(createMongoAbility);

  if (!user) {
    return build();
  }

  // Application admin
  if (userHasRole(user, Role.APPLICATION_ADMIN)) {
    can(Action.MANAGE, Subject.ALL);
  }

  // Clients
  if (userHasRole(user, Role.CLIENT_ADMIN)) {
    can(Action.MANAGE, Subject.CLIENT);
  }
  if (userHasRole(user, Role.CLIENT_EDITOR)) {
    can(Action.CREATE, Subject.CLIENT);
    can(Action.UPDATE, Subject.CLIENT);
  }
  if (userHasRole(user, Role.CLIENT_VIEWER)) {
    can(Action.READ, Subject.CLIENT);
  }
  if (userHasRole(user, Role.CLIENT_VIEWER_SENSITIVE)) {
    can(Action.READ_SENSITIVE, Subject.CLIENT);
  }

  // Contacts
  if (userHasRole(user, Role.CONTACT_ADMIN)) {
    can(Action.MANAGE, Subject.CONTACT);
  }
  if (userHasRole(user, Role.CONTACT_EDITOR)) {
    can(Action.CREATE, Subject.CONTACT);
    can(Action.UPDATE, Subject.CONTACT);
  }
  if (userHasRole(user, Role.CONTACT_VIEWER)) {
    can(Action.READ, Subject.CONTACT);
  }
  if (userHasRole(user, Role.CONTACT_VIEWER_SENSITIVE)) {
    can(Action.READ_SENSITIVE, Subject.CONTACT);
  }

  return build();
};

However, when I try to destructure the result of the defineAbilityFor function, I get the @typescript-eslint/unbound-method warning:

const { can } = defineAbilityFor(user);

I saw a related issue (#736) that seemed to suggest it was resolved but I'm still getting the error. Is there a better way to create the AbilityBuilder or to return the result that would get rid of this warning? Any help would be appreciated!

[stalniy]

AbilityBuilder can/cannot methods are very complicated in terms of type inference.

Eslint thinks the method is unbound because it cannot detect bound methods created with .bind

so methods are bound be sure.

I’ve tried to rewrite AbilityBuilder so eslint understand that methods are bound but I remember it brought even more complexities. That’s why those changes have not been released

If you want to get rid of that issue with deli t just use a variable

const b = new AbilityBuilder<AppAbility>(createMongoAbility);

b.can(…)

[ericvoshall]

Got it, thank you for the explanation.