Postgresql gorm 创建并返回值 many2many

我想创建一个数据，然后返回值，但该值与另一个表相关.

User response struct个

type UserRespone struct {
    ID        int           `json:"id,omitempty"`
    Email     string        `json:"email"`
    FirstName string        `json:"first_name"`
    LastName  string        `json:"last_name"`
    Address   string        `json:"address"`
    Roles     []roles.Roles `json:"roles" gorm:"many2many:users_roles;foreignKey:ID;joinForeignKey:UserID;references:ID;joinReferences:RolesID"`
}

Roles struct个

type Roles struct {
    ID   int `json:"id" gorm:"<-:false;primaryKey"`
    Name string
}

这是一个创建数据的函数，我想返回值[]Roles.Roles

func (r *UserRepositoryImpl) AuthSignUp(ctx context.Context, req user.AuthSignUp) (user.UserRespone, error) {
    createdUser := req.ToUser()
    
    hashPassword, _ := bcrypt.GenerateFromPassword([]byte(createdUser.Password), bcrypt.DefaultCost)

    createdUser.Password = string(hashPassword[:])

    result := r.Db.
        WithContext(ctx).
        Create(&createdUser)

    for _, rolesID := range req.RolesID {
        userRole := new(user.UsersRoles)

        userRole.UserID = createdUser.ID
        userRole.RolesID = rolesID
        result = r.Db.WithContext(ctx).Create(&userRole)
    }

    return createdUser.ToResponse(), result.Error
}

我想像这样返回值:

user.UserResponse{
        ID:        4,
        Email:     "putri4@gmail.com",
        FirstName: "putri",
        LastName:  "cantik",
        Address:   "bonang",
        Roles: []roles.Roles{
            {
                ID: 1,
                Name: "Admin",
            },
            {
                ID: 2,
                Name: "Consumer",
            },
        },
    }

但当我创建一个数据集时，我只得到如下值:

user.UserRespones{
        ID:        4,
        Email:     "putri4@gmail.com",
        FirstName: "putri",
        LastName:  "cantik",
        Address:   "bonang",
        Roles:     []roles.Roles(nil),
    }