Hide fields in Golang Gorm

Question

I am using Gorm in my Golang project. Exctly I have a Rest-API and I get a request make the process and return an object, so, for example I have a struct User like this:

type User struct {
    gorm.Model
    Password []byte
    Active bool
    Email string
    ActivationToken string
    RememberPasswordToken string
}

Now, when I create a User I am encoding it to JSON with:

json.NewEncoder(w).Encode(user)

But in the client side I am receiving some fields that I don't really want to send/receive, for example: Created_At, Deleted_At, Updated_At, Password. So, what is the best way to ignore or hide that fields in the response? I saw that I can use a library called Reflect, but it seems to be a lot of work for a simple thing and I want to know if there's another way. Thank you very much

Zaffer

Either have separate models for what you're going to be returning and storing in the database, don't export the field, or you can use a json attribute to ignore the field i.e. Password []byte `json:'-'` – Fabiano

@Gavin, is it even possible to change those attributes on an external struct? – Myopic

@Myopic When was the struct mentioned to be external? – Fabiano

gorm.Model contains anonymous fields within the User struct. I'm assuming OP wants to restrict visibility to those fields. – Myopic

@Myopic Ah, yeah you're right. I would probably make a separate model for the response then. That sounds like the easiest solution and also separates the database specific information from what the end user sees. – Fabiano

Answer 1

As Gavin said, I would suggest having two separate models and giving the model the ability to convert to the correct return type.

models/user.go

package models

type User struct {
    gorm.Model
    Password []byte
    Active bool
    Email string
    ActivationToken string
    RememberPasswordToken string
}

func (u *User) UserToUser() app.User {
    return app.User{
        Email: u.Email
    }
}

app/user.go

package app

type User struct {
    Email string
}

Chromatics

if we use preload/joins do we have to loop every object to convert it to other struct? – Graduated

Answer 2

If you want to have a fixed object to return, you can change the tags with json:"-" to decide the elements to send with json. For the elements in the gorm.Model:

type Model struct {
    ID        uint `gorm:"primary_key"`
    CreatedAt time.Time
    UpdatedAt time.Time
    DeletedAt *time.Time `sql:"index"`
}

You can substitute them for your own struct:

type OwnModel struct {
    ID        uint       `gorm:"primary_key"`
    CreatedAt time.Time  `json:"-"`
    UpdatedAt time.Time  `json:"-"`
    DeletedAt *time.Time `json:"-";sql:"index"`
}

So, your User struct would be like that:

type User struct {
    OwnModel
    Password []byte
    Active bool
    Email string
    ActivationToken string
    RememberPasswordToken string
}

The other User fields is your decision to add or not `json:"-"` tag.

Wildfowl

Answer 3

For me helped add json:"-" to gorm.Model

For example:

type User struct {
    gorm.Model `json:"-"`
    Password []byte
    Active bool
    Email string
    ActivationToken string
    RememberPasswordToken string
}

Cavin

Answer 4

I found a way to hide the relation to my User model from my Sessions model by creating an inherited struct with an omitempty

// Trick to hide the User assocation from the results
type Session struct {
    models.Session
    User *models.User `json:"User,omitempty"`
}

func Token(c *fiber.Ctx) error {
    user := auth.User(c)
    var sessions []Session
    database.Db.Find(&sessions, "user_id = ?", user.ID)
    return render.Render(c, sessions)
}

I hope this helps - i also added a feature request - i think this would be great built-in to gorm

https://github.com/go-gorm/gorm/issues/5746

Kukri

Answer 5

type OrmModel struct {
    gorm.Model `json:"-"`
    ID        uint  `gorm:"primarykey" json:"id,omitempty"`
}
type User struct {
    OrmModel
    Password []byte
    Active bool
    Email string
    ActivationToken string
    RememberPasswordToken string
}

Frenchify