How I can I avoid having validation for update while having it for create? For instance:
I wish to have an image field to have presence validation on create. But want to avoid it in edit and assume the previous value in case of no change.
Note: I am using Padrino.
In Sequel, validations are generally done at the instance level using the validation_helpers plugin. So you just use a standard ruby conditional if you only want to validate it for new objects and not for existing ones:
plugin :validation_helpers
def validate
super
validates_presence :image if new?
end
you can say something like:
validates :image, :presence => true, on: :create
that means you will do validation only when do create.
In Rails,
The "validates" keyword in Rails takes a parameter that allows you to do this:
validates :your_validator, :presence => true, :on => :create
You can also pass an array there:
validates :your_validator, :presence => true, :on => [:create, :update]
In Padrino,
I believe padrino using datamapper - DM has contextual validations. So, you could do a contextual validation.
validates :image, :presence => true, :when => [:custom]
Then while saving, you can do this:
post.save(:custom)
# OR
post.valid?(:custom)
The context :custom can be used in different places.
