How to write error depending on field in which the @Column({ unique: true }) Decorator failed. Error Code 23505

Question

I am trying to write a Sign Up exception to let the user know if their username OR email was already in use. Using the decorator @Column({ unique: true}) allows me to catch the error 23505, but it is the same error regardless of whether it is the username or email that fails. Is there a way I can determine which of the properties I am catching the error on and write a separate exception for each?

  const user = this.create({
      username,
      email,
      password: hashedPassword,
    });
    try {
      await this.save(user);
    } catch (error) {
      console.log(error.code);
      if (error.code === '23505') {
        throw new ConflictException('Username already exists');
      } else {
        throw new InternalServerErrorException();
      }
    }

@Entity()
export class User {
  @PrimaryGeneratedColumn('uuid')
  id: string;

  @Column({ unique: true })
  username: string;

  @Column({ unique: true })
  email: string;

  @Column()
  password: string;
}

Answer 1

You should check this code. If you want to separate the error, you need to check it both. I'm not sure you are using typeORM. I'm using a TypeORM in this code.

    const user = this.create({
      username,
      email,
      password: hashedPassword,
    });
    try {
      // check if there is same username
      const findName = await this.findOne({
        username : username
      })
      // if the username exist, throw a error
      // if not, it will be 'undefined'
      if(findName){
        throw new ConflictException('Username already exists');
      }

      // check if there is same email
      const findEmail = await this.findOne({
        email : email
      })
      // if the email exist, throw a error
      // if not, it will be 'undefined'
      if(findEmail){
        throw new ConflictException('Email already exists');
      }

      await this.save(user);
    } catch (error) {
      console.log(error.code);
      if (error.code === '23505') {
        throw new ConflictException('Username already exists');
      } else {
        throw new InternalServerErrorException();
      }
    }