How to Update Multiple Attribute With Struct

Question

I was trying to make a function that can update user by given parameter.

My Method:

func UpdateMultiple(db *gorm.DB, user *User, id uint32) error {
    usr := User{}

    err := db.Debug().Model(User{}).Where("id = ?", id).Updates(map[string]interface{}{"email": user.Email, "is_active": false}).Take(&usr).Error
    if err != nil {
        return err
    }
    return nil
}

And Using like this:

Updater := &User{
    Email:    holder.Email,
    IsActive: false,
}
err = UpdateMultiple(s.DB, Updater, id)

It is working fine for now.But If want to update another field i have to change my UpdateMultiple() method. Is there any other way i can update without changing method but only changing given parameters value?

Anton · Accepted Answer · 2020-05-17 07:20:13Z

3

You can pass your User model to the Updates function, it will update all struct fields with non blank value (which means that all fields should be pointers, in order to make the best use of this feature). The code would look like this:

func UpdateMultiple(db *gorm.DB, user *User, id uint32) error {
     return db.Debug().
          Model(User{}).
          Where("id = ?", id).
          Updates(user).Error

}

See some examples from the official documentation:

// Update multiple attributes with `struct`, will only update those changed & non blank fields
db.Model(&user).Updates(User{Name: "hello", Age: 18})
//// UPDATE users SET name='hello', age=18, updated_at = '2013-11-17 21:34:10' WHERE id = 111;

// WARNING when update with struct, GORM will only update those fields that with non blank value
// For below Update, nothing will be updated as "", 0, false are blank values of their types
db.Model(&user).Updates(User{Name: "", Age: 0, Actived: false})

edited May 17, 2020 at 7:20

answered May 17, 2020 at 7:09

Anton

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8 Comments

Eklavya Over a year ago

How do you update a field with blank value means null in database ?

Anton Over a year ago

@Eklavya you mean how to erase, set field as NULL in db?

Eklavya Over a year ago

Yes, may be then it ignores the update. That's it's quite risky.

Anton Over a year ago

@Eklavya then map[string]interface{} has to be passed to the Updates function. "field_a": nil will set it to NULL in db. That's a peculiarity of this approach, you have to specify explicitly when you want to set a field to NULL.

Eklavya Over a year ago

Yes, I know that's why I am not suggesting non blank field approach.

|

Arvind Kumar Avinash · Accepted Answer · 2020-05-18 13:21:57Z

0

Since you need dynamic field update, fetch user first by id

user := &User{}
db.First(&user, id)

Update the field you want to update

user.Email = "[email protected]"
user.IsActive = false

And update the user info

db.Save(&user)

Or

Create map[string]interface{} and add which field you want to update.

mp := make(map[string]interface{})
mp["email"] = holder.Email
mp["is_active"] =  false

And update the user

db.Model(User{}).Where("id = ?", id).Updates(mp)

edited May 18, 2020 at 13:21

Arvind Kumar Avinash

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answered May 17, 2020 at 5:33

Eklavya

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1 Comment

Md Ariful islam Protik Over a year ago

I never thought of that. Thanks for Quick Response! Let me Try

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