Gorm Understanding Foreign Keys/One-to-Many

How can I use 1 - Many Relationships

I'm at a loss how to make this work. I've extensively experimented, and reviewed the documentation, and I'm just not seeing how to make this go. I'm trying to embed a user's roles in the User model, and it's returning null. I have two models:

type User struct {
    ID        uint      `gorm:"primaryKey" json:"id"`
    UserName     string    `json:"user_name,omitempty"`
    FullName     string    `json:"full_name,omitempty"`
    EmailAddress string    `json:"email_address,omitempty"`
    Password     string    `json:"password,omitempty"`
    ApiKey       string    `json:"api_key,omitempty"`
    Enabled      bool      `json:"enabled,omitempty"`
    LastSignin   time.Time `json:"last_signin,omitempty"`
    Roles        []UserRole `json:"roles"`
}

and:

type UserRole struct {
    UserID uint `gorm:"primaryKey" json:"user_id"`
    RoleID uint `gorm:"primaryKey" json:"role_id"`
    Role string `gorm:"->" json:"role"`
}

func (UserRole) TableName() string {
    return "vuserroles"
}

vUserRoles is:

CREATE TABLE systemroles (
    id BIGINT NOT NULL DEFAULT NEXTVAL('systemroles_seq'),
    role VARCHAR(64),
    created_at TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT CURRENT_TIMESTAMP,
    CONSTRAINT PK_USERROLES PRIMARY KEY (id),
    CONSTRAINT UQ_USERROLES_ROLE UNIQUE (role)
    );

CREATE TABLE user_roles (
    user_id BIGINT NOT NULL,
    role_id BIGINT NOT NULL,
    CONSTRAINT PK_USER_ROLES PRIMARY KEY (user_id, role_id),
    CONSTRAINT FK_USER_ROLES_USERS FOREIGN KEY (user_id) REFERENCES users ON DELETE CASCADE,
    constraint FK_USER_ROLES_ROLES FOREIGN KEY (role_id) REFERENCES systemroles ON DELETE CASCADE
    );

CREATE VIEW vUserRoles AS
    SELECT user_roles.*,
        systemroles.role
    FROM user_roles
        INNER JOIN systemroles
        ON systemroles.id=user_roles.role_id;

I can retrieve the roles directly:

    cfg := config.GetConfig()
    db, err := gorm.Open(postgres.Open(cfg.GetDatabaseDSN()), &gorm.Config{})
    if err != nil {
        fmt.Println(err)
    }
    id := ctx.Param("id")
    var roles []models.UserRole
    db.Where("user_id=?",id).Find(&roles)

returns:

    {
        "user_id": 1,
        "role_id": 1,
        "role": "admin"
    },
    {
        "user_id": 1,
        "role_id": 2,
        "role": "editor"
    }

I tried defining:

    Roles        []UserRole `gorm:"foreignKey:UserID" json:"roles"`

as well as:

    Roles        []UserRole `gorm:"foreignKey:user_id" json:"roles"`
````

and it doesn't work. They don't generate an error, but roles is null.

Roles []UserRole gorm:"foreignKey:UserIDXX" json:"roles".
````

generates an error.

The document you expected this should be explained

https://gorm.io/docs/has_many.html

Expected answer

I'd like to know how to have the value for roles populate. I'd really appreciate some help with this. Thanks.

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