refactoring

Resolve #7779

packages/backend/src/models/entities/user-group-joining.ts

@@ -0,0 +1,42 @@
+import { PrimaryColumn, Entity, Index, JoinColumn, Column, ManyToOne } from 'typeorm';
+import { User } from './user';
+import { UserGroup } from './user-group';
+import { id } from '../id';
+
+@Entity()
+@Index(['userId', 'userGroupId'], { unique: true })
+export class UserGroupJoining {
+	@PrimaryColumn(id())
+	public id: string;
+
+	@Column('timestamp with time zone', {
+		comment: 'The created date of the UserGroupJoining.'
+	})
+	public createdAt: Date;
+
+	@Index()
+	@Column({
+		...id(),
+		comment: 'The user ID.'
+	})
+	public userId: User['id'];
+
+	@ManyToOne(type => User, {
+		onDelete: 'CASCADE'
+	})
+	@JoinColumn()
+	public user: User | null;
+
+	@Index()
+	@Column({
+		...id(),
+		comment: 'The group ID.'
+	})
+	public userGroupId: UserGroup['id'];
+
+	@ManyToOne(type => UserGroup, {
+		onDelete: 'CASCADE'
+	})
+	@JoinColumn()
+	public userGroup: UserGroup | null;
+}