TypeORM OneToMany relation doesn't add entry to the array when it is created

Question

I am trying to create two entities - Assignment and Lesson. Each Lesson can have multiple Assignments and each Assignment can be part of one Lesson. When I create a Lesson with Assignments in it, the Assignemnts get created, they are added to the assignments array and everything works.

When I create a Lesson and then try to add a new Assignment to it, the Assignment is created, it is linked to the correct Lesson but the assignments field in the Lesson is not updated.

Is this how it is supposed to work or is there any way to update the assignments array in Lesson?

Below is my code. I am using a sqlite in-memory database

Assignment.ts

import { Entity, Column, PrimaryGeneratedColumn, TableInheritance, ManyToOne, JoinColumn } from 'typeorm';
import { Lesson } from './Lesson';

@Entity()
@TableInheritance({ column: { type: 'varchar', name: 'type' } })
export abstract class Assignment {
    @PrimaryGeneratedColumn()
    id: number;

    @Column()
    name: string;

    @ManyToOne(() => Lesson, (lesson) => lesson.assignments, { eager: true })
    @Column('json')
    lesson: Lesson;
}

Lesson.ts

import { Entity, Column, PrimaryGeneratedColumn, OneToMany } from 'typeorm';
import { Assignment } from './Assignment';

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

    @Column()
    name: string;

    @OneToMany(() => Assignment, (assignment) => assignment.lesson, { cascade: true })
    @Column('json')
    assignments: Assignment[];
}

I have tried adding @JoinColumn() to the @ManyToOne relation but nothing changed

Answer 1

The solution was to remove the @Column annotation from both of the fields - assignments and lesson.

I could also add a filed lessonId: number with the @Column annotation to store the lesson id in the Assignment.