typeorm/docs/entity-inheritance.md

Entity Inheritance

You can reduce duplication in your code by using entity inheritance.

For example, you have Photo, Question, Post entities:

@Entity()
export class Photo {
    
    @PrimaryGeneratedColumn()
    id: number;
 
    @Column()
    title: string;
    
    @Column()
    description: string;
    
    @Column()
    size: string;
    
}

@Entity()
export class Question {
    
    @PrimaryGeneratedColumn()
    id: number;
 
    @Column()
    title: string;
    
    @Column()
    description: string;
    
    @Column()
    answersCount: number;
    
}

@Entity()
export class Post {
    
    @PrimaryGeneratedColumn()
    id: number;
 
    @Column()
    title: string;
    
    @Column()
    description: string;
    
    @Column()
    viewCount: number;
    
}

As you can see all those entities have common columns: id, title, description. To reduce duplication and produce a better abstraction we can create a base class called Content for them:

export abstract class Content {
    
    @PrimaryGeneratedColumn()
    id: number;
 
    @Column()
    title: string;
    
    @Column()
    description: string;
    
}
@Entity()
export class Photo extends Content {
    
    @Column()
    size: string;
    
}

@Entity()
export class Question extends Content {
    
    @Column()
    answersCount: number;
    
}

@Entity()
export class Post extends Content {
    
    @Column()
    viewCount: number;
    
}

All columns (relations, embeds, etc.) from parent entities (parent can extend other entity as well) will be inherited and created in final entities.