I'm working with Nest.js, TypeORM, and PostgreSQL, I have two entities(product and stone) with a many to many relation, based on my own business project, I have to add one extra column to that many to many table(product_stone), but I have some issue with my solution, at first I try to create a product with a set of stones:
"stones": [
{"id": 1,"count":1},
{"id": 2,"count": 3}
]
and after that, I try to add the count to the product_stone table by updating it, the result will be like this: product_stone_table till here everything is Okay, but every time that I restart the server all of the data in that extra column will be set to its default value(null): product_stone_table
And also I tried to do not set the count to {nullable:true} in product_stone table and add count during the creation of a product, but when I want to restart the server I receive an error kile this:
QueryFailedError: column "count" of relation "product_stone" contains null values
Is there anybody to guide me?
product.entity.ts
@Entity()
export class Product extends BaseEntity {
@PrimaryGeneratedColumn()
id: number;
@ManyToMany(() => Stone)
@JoinTable({
name: 'product_stone',
joinColumn: {
name: 'productId',
referencedColumnName: 'id',
},
inverseJoinColumn: {
name: 'stoneId',
referencedColumnName: 'id',
},
})
stones: Stone[];
}
stone.entity.ts
@Entity()
export class Stone extends BaseEntity {
@PrimaryGeneratedColumn()
id: number;
@Column()
title: string;
}
product_stone.entity.ts
@Entity('product_stone')
export class ProductStone extends BaseEntity {
@Column({ nullable: true })
count: number;
@Column()
@IsNotEmpty()
@PrimaryColumn()
productId: number;
@Column()
@IsNotEmpty()
@PrimaryColumn()
stoneId: number;
}
I don't think you can define custom attributes on many-to-many table like that.
From documentation:
In case you need to have additional properties in your many-to-many relationship, you have to create a new entity yourself
In your case that would mean you would have to so something like that:
// product_stone.entity.ts
@Entity()
export class ProductToStone {
@PrimaryGeneratedColumn()
public id: number;
@Column()
public productId: number;
@Column()
public stoneId: number;
@Column()
public count: number;
@ManyToOne(() => Product, product => product.productToStone)
public product: Product;
@ManyToOne(() => Stone, stone => stone.productToStone)
public stone: Stone;
}
// product.entity.ts
...
@OneToMany(() => ProductToStone, productToStone => postToCategory.product)
public productToStone!: PostToCategory[];
// stone.entity.ts
...
@OneToMany(() => ProductToStone, postToCategory => postToCategory.stone)
public postToCategories!: PostToCategory[];