TailwindFormBuilder

example.rb

class TailwindFormBuilder < ActionView::Helpers::FormBuilder
  ERROR_FIELD_CLASS = "is-invalid"
  ERROR_FEEDBACK_CLASS = "invalid-feedback"

  def field_class(attribute)
    ERROR_FIELD_CLASS if object.errors.key?(attribute)
  end

  def errors_for(attribute, attrs = {})
    return if object.blank?
    return unless object.errors.key?(attribute)
    message = object.errors[attribute].join(', ').html_safe
    class_name = "#{ERROR_FEEDBACK_CLASS} #{attrs[:class]}".strip
    @template.tag.p(message, class: class_name)
  end

  def text_field(method, options = {})
    options[:class] = field_class_with_validation(method, options[:class])
    super
  end

  def text_area(method, options = {})
    options[:class] = field_class_with_validation(method, options[:class])
    super
  end

  def email_field(method, options = {})
    options[:class] = field_class_with_validation(method, options[:class])
    super
  end

  def password_field(method, options = {})
    options[:class] = field_class_with_validation(method, options[:class])
    super
  end

  def phone_field(method, options = {})
    options[:class] = field_class_with_validation(method, options[:class])
    super
  end

  def number_field(method, options = {})
    options[:class] = field_class_with_validation(method, options[:class])
    super
  end

  def date_field(method, options = {})
    options[:class] = field_class_with_validation(method, options[:class])
    super
  end

  def check_box(method, options = {}, checked_value = "1", unchecked_value = "0")
    options[:class] = field_class_with_validation(method, options[:class])
    super
  end

  def select(method, choices = nil, options = {}, html_options = {}, &block)
    html_options[:class] = field_class_with_validation(method, html_options[:class])
    super
  end

  private

    def field_class_with_validation(attribute, field_class)
      return field_class if object.blank?
      return field_class unless object.errors.key?(attribute)
      return field_class if field_class&.include?(ERROR_FIELD_CLASS)
      [field_class, ERROR_FIELD_CLASS].compact.join(' ')
    end
end