Dynamically set method on before_save

In my controller i want to dynamically bind my instance method to the before_save call开发者_开发问答backs.

Is there any ways we can dynamically bind methods to the callback from controller side....

EDIT :

Controller

This original code..

def amfupdate
  set_properties
  validate_record  if params[:csv_header][:validate_record] == "Y" #On this condition...
  super
end

If condition is true than i want to set custom callback that will exact call after before_save but before object is saved.

I want to call this method exact after before_save.. But if condition is true on controller side ..

In Model

def validate_record
  self.csv_columns.each do |csv_column|
    self.errors.add_to_base(_("Invalid column name #{csv_column.column_name}.")) \
      unless self.model_name.constantize.column_names.include?(csv_column.column_name)
  end
end

---

I think you're looking for something like the following. In the Model:

validate do |instance|
  instance.csv_columns.each do |csv_column|
    instance.errors.add :csv_columns, "Invalid column name #{csv_column.column_name}"
      unless instance.class.column_names.include?(csv_column.column_name)
  end
end

This will be called before the record is saved and will abort the save if the errors are added to

UPDATE: With suggestion for conditional validations

Add an attribute to the model

attr_accessor :some_condtional

Set this in the controller

@instance.some_conditional = true # or false

Then the validation now looks like this:

validate do |instance|
  instance.csv_columns.each do |csv_column|
    instance.errors.add :csv_columns, "Invalid column name #{csv_column.column_name}"
      unless instance.class.column_names.include?(csv_column.column_name)
  end if instance.some_conditional
end

Or something along those lines. In other words use the model to hold the state and communicate the logic