fix: @Expose decorator exposes class property names when working with Maps

[panki]

import 'reflect-metadata';

import { Expose, plainToClass, Type } from 'class-transformer';

export class Skill {
  @Expose() name: string;
}

export class Weapon {
  @Expose() name: string;
  @Expose() range: number;
}

export class Player {
  name: string;

  @Expose()
  @Type(() => Skill)
  skills: Set<Skill>;

  @Expose()
  @Type(() => Weapon)
  weapons: Map<string, Weapon>;
}

const v = {
  name: 'name',
  skills: new Set([
    { name: 'skill1', remove: 1 },
    { name: 'skill2', remove: 2 },
  ]),
  weapons: new Map([
    ['w1', { name: 'weapon1', range: 1, remove: 1 }],
    ['w2', { name: 'weapon2', range: 2, remove: 2 }],
  ]),
};

console.log(
  plainToClass(Player, v, {
    excludeExtraneousValues: true,
  }),
);

Output:

Player {
  skills: [ Skill { name: 'skill1' }, Skill { name: 'skill2' } ],
  weapons: Map { 'name' => undefined, 'range' => undefined }
}

Expected output:

Player {
  skills: [ Skill { name: 'skill1' }, Skill { name: 'skill2' } ],
  weapons: Map {
    'w1' => Weapon { name: 'weapon1', range: 1 },
    'w2' => Weapon { name: 'weapon2', range: 2 }
  }
}

[randfur]

We are encountering this issue as well. Using @Expose seems to mess up @Type for Map fields and add the inner type's fields to the map.

[cvlvxi]

It appears that when adding @Expose() to the nested class in conjunction with @Type where its tied to a Map<string,T> type does the following

    class Weapon {
      @Expose() name: string;
      @Expose() range: number;
    }

   class Player {
      @Expose() name: string
      @Expose()
      @Type(() => Weapon)
      weapons: Map<string, Weapon>;
    }

    const json = {
      name: "name",
      weapons: {
        "w1": { name: "weapon1", range: 1 },
        "w2": { name: "weapon2", range: 2}
      }
    };

    console.log(
      plainToClass(Player, json, {
        excludeExtraneousValues: false,
      })
    )

Result

    Player {
      name: 'name',
      weapons: Map {
        'w1' => Weapon { name: 'weapon1', range: 1 },
        'w2' => Weapon { name: 'weapon2', range: 2},
        'name' => undefined,
        'range' => undefined
      }
    }

• You can see that it added the Weapon properties as the string keys of the Map which doesn't seem right..
• As you can see here:

        'name' => undefined,
        'range' => undefined

• This is with Expose() added and also excludeExtraneousValues set to false
• When we set excludeExtraneousValues to true we get the abnormal behaviour that the above users is experiencing

    class Weapon {
      @Expose() name: string;
      @Expose() range: number;
    }

    class Player {
      @Expose() name: string;

      @Expose()
      @Type(() => Weapon)
      weapons: Map<string, Weapon>;
    }

    const json = {
      name: "name",
      weapons: {
        "w1": { name: "weapon1", range: 1 },
        "w2": { name: "weapon2", range: 2}
      }
    };

    console.log(
      plainToClass(Player, json, {
        excludeExtraneousValues: true,
      })
    );
  });

Result

    Player {
      weapons: Map { 'name' => undefined, 'range' => undefined }
    }

[NoNameProvided]

This has been fixed in develop via #405 and be included in the next release.

[github-actions]

This issue has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.