get validations from model

Question

How cat I get list of validations defined in model

Example:

class ModelName
  validates_presence_of :field_name
  validates_inclusion_of :sex, :in => %w(M F)
end

I need Hash like:

{:field_name => 'required', :sex => 'Must be in: M, F'}

Deceive

Answer 1

You don't need a plugin for basic needs.

You can do this to get a hash of all validators.

ModelName.validators

If you want to get the validators for a specific field :

ModelName.validators_on(:attribute)

Edea

Cool! It's better, than plugin – Deceive

Just a note, this is only available in Rails 3. For earlier rails apps, the plugin is the way to go. – Ferritin

How can I get this if I am using a custom validate method like validate :check_name_blank Inside this method I am checking name is present and some other stuffs. So while I am doing ModelName.validators_on :name, I am getting an empty array. – Ottie

Answer 2

This code yields an array of required fields. It should be adaptable to your needs.

@required_fields = []
ModelName.validators.each do |v|
  @required_fields << v.attributes.first if v.kind == :presence
end

Moonseed

Answer 3

If you add validations dynamically in your models, you can use the instance to list the validations:

product = Product.new
product.singleton_class.validators_on(:price)
#=> [#<ActiveModel::Validations::PresenceValidaton>]

Tested in Rails 5.2.

Paterfamilias

Answer 4

Looks like there's no native way to do it, but a quick Google (for "rails reflect validations") turns up this plugin.

Nunez

Answer 5

This code work for me:

ModelName.validators_on(:sex).first.options[:in]

answer: ["M","F"]

You want something like this:

field = :sex
sexs = ModelName.validators_on(field).first.options[:in]
hsh = {}
hsh[:field_name] = (ModelName.validators.grep(ActiveRecord::Validations::PresenceValidator).flat_map(&:attributes).include?(field)) ? 'required': 'optional'
hsh[field] ="Must be in: #{sexs.to_sentence(two_words_connector: ', ')}"

answer hsh: {:field_name=>"required", :sex=>"Must be in: M, F"}

I use Rails 6.1.4.1

Sampling