get validations from model

问题

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'}

回答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)

回答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

回答3:

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

回答4:

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.

来源：https://stackoverflow.com/questions/4051864/get-validations-from-model