Entity

import { Entity, Column, PrimaryGeneratedColumn } from 'typeorm';

@Entity()
export class Cat {
  @PrimaryGeneratedColumn()
  id: number;

  @Column({ length: 500 })
  name: string;

  @Column('int')
  age: number;

  @Column()
  breed: string;
}

Service:

@Injectable()
export class CatsService {
  constructor(
    @InjectRepository(Cat)
    private repository: Repository<Cat>
  ) {}

  create(cat: Cat) {
    return this.repository.create(cat);
  }

  findAll() {
    return this.repository.find();
  }
}