Many to Many (bidirectional) - table path is undefined (bug in documentation?)

Issue type:

[ ] question [x] bug report [ ] feature request [ ] documentation issue

Database system/driver:

[ ] cordova [ ] mongodb [ ] mssql [x] mysql / mariadb [ ] oracle [ ] postgres [ ] sqlite [ ] sqljs [ ] react-native [ ] expo

TypeORM version:

[x] latest [ ] @next [ ] 0.x.x (or put your version here)

Steps to reproduce or a small repository showing the problem: User entity

@Entity()
export class User {
  @PrimaryGeneratedColumn({
    type: "bigint",
    unsigned: true
  })
  id: number;

  @Column("varchar")
  name: string;

  @ManyToMany(type => Role)
  @JoinTable({
    name: "user_role",
    joinColumns: [{ name: "userId" }],
    inverseJoinColumns: [{ name: "roleId" }]
  })
  roles: Role[];
}

Role entity

@Entity()
export class Role {
  @PrimaryGeneratedColumn({
    type: "bigint",
    unsigned: true
  })
  id: number;

  @Column("varchar")
  name: string;

  @ManyToMany(type => User, user => user.roles)
  users: User[];

  @CreateDateColumn()
  createdAt: string;

  @UpdateDateColumn()
  updatedAt: string;
}

Then query:

db
    .getRepository(Role)
    .createQueryBuilder("role")
    .leftJoin("role.users", "user")
    .where("user.id = :id", { id: 1 })
    .getMany();

Error: TypeError: Cannot read property ‘tablePath’ of undefined

Everything is done the same as in documentation: http://typeorm.io/#/many-to-many-relations If I add @JoinTable to the “Role” entity, everything is working fine, but documentation cleary says: “We just made our relation bi-directional. Note, the inverse relation does not have a @JoinTable. @JoinTable must be only on one side of the relation.”

What is more, when the @JoinTable decorator is on both sides, it spoils inserting many to many:

db
 .createQueryBuilder()
 .relation(User, "roles")
 .of(2) //User id
 .add(10); // Role id

It produces query: ‘INSERT INTO user_role(userId, roleId) VALUES (10, 2)’ Foreign keys are switched.