[avaram] Skip save on specified field if this fields content is blank in before_save

[zw963]

I use avram with kemal.

Following is a example.

class UpdateUser < User::SaveOperation
  permit_columns licenses_allowed_creation_times, password
  
  before_save do
    if licenses_allowed_creation_times.value.blank? || !licenses_allowed_creation_times.changed?
	  # Need skip save on licenses_allowed_creation_times column here
    end
	
	# others password update logic here.
  end
end

I guess, if no add before_save hook, the value from licenses_allowed_creation_times column will always be saved to db, right?

so, how can i skip updated this column instead?

thank you.

[jwoertink]

If you remove the licenses_allowed_creation_times from the permit_columns, then it won't set the value from params.

class UpdateUser < User::SaveOperation
  permit_columns password
  
  before_save do
	
	# others password update logic here.
  end
end

If you need it in some cases, you could have a separate operation for that.

class UpdateUserPassword < User::SaveOperation
  include DefaultUserValidations
  permit_columns password
end

class UpdateUserLicenses < User::SaveOperation
  include DefaultUserValidations
  permit_columns licenses_allowed_creation_times
end

You could try something like that.

[jwoertink]

When the record is passed in user the attribute sets the original_value to what was pulled from the database. Then when a named arg or param value is passed in, that sets the value. That way we can see if the value changed like

if licenses_allowed_creation_times.changed?(from: "this", to: "that")
  # ...
end

by comparing original_value and value. It should work on updated_at too. updated_at.value = updated_at.original_value since it won't set the value to that if it already has one

https://github.com/luckyframework/avram/blob/5c553aa7bd67a8ec8f00050eddda8adcdd0a72f8/src/avram/save_operation.cr#L389-L390

[zw963]

Hi, sorry for my bad english.

  before_save do
    if licenses_allowed_creation_times.value.nil?
    # ignore updating it...
     licenses_allowed_creation_times.value = licenses_allowed_creation_times.original_value
    end
  end

The question is, when update only one column, use licenses_allowed_creation_times.value = licenses_allowed_creation_times.original_value, as above code, if will caused the updated_at column get auto updated to Time.utc?

i want to know, if just save value with original_value like this, if will touch the DB and save same value on DB, and trigger the updated_at hook, and update the value of updated_at ?

[jwoertink]

Yes. The updated_at will always be updated when updated_at.value is nil. A database call is always made even if nothing is being changed.

user = UserQuery.first

User::SaveOperation.update(user) do |_, _|
  # still makes a database call and updates updated_at
end

[jwoertink]

@zw963 I just came up with a new idea on how to clean this up that you can try if you want:

UpdateUserLicenses.update!(user, **params, licenses_allowed_creation_times: licenses_allowed_creation_times || Avram::Nothing.new)

I wonder if we can just make a global constant for this like:

IGNORE_VALUE = Avram::Nothing.new

Then if licenses_allowed_creation_times is nil, and you want to ignore it instead of using the nil value, you'd just do

SomeOp.update(this, some_param: some_param || IGNORE_VALUE)

This would obviously cause issues if the value could be a boolean false... but something to consider I guess 😄

[zw963]

Okay, i guess if apply the new idea, my code will change to following form: (avram + kemal), and remove the licenses_allowed_creation_times.value = licenses_allowed_creation_times.original_value in before_save hook of UpdateUser, right?

  post path.admin_update_user do |env|
      user = get_user(env).not_nil!

      licenses_allowed_creation_times = env.params.body["licenses_allowed_creation_times"]

      if licenses_allowed_creation_times.present?
        value = licenses_allowed_creation_times.to_i
      else
        value = Avram::Nothing.new
      end

      params = {
        password:                        env.params.body["password"].as(String),
        password_confirmation:           env.params.body["password_confirmation"].as(String),
        licenses_allowed_creation_times: value,
      }

      UpdateUser.update(user, **params) do |operation, updated_user|
        if operation.saved?
          env.session.destroy
          env.redirect path.admin_users_index
        else
          errors = operation.errors
          render_use_layout "admin/users/edit.ecr"
        end
      end
    end

I think it should work, if i am not misunderstood the means of Avram::Nothing.new, but we have to move logic to kemal block instead of before_save, i still consider hidden following saving logic into avram, make kemal part is more simple is better?

      licenses_allowed_creation_times = env.params.body["licenses_allowed_creation_times"]

      if licenses_allowed_creation_times.present?
        value = licenses_allowed_creation_times.to_i
      else
        value = Avram::Nothing.new
      end