Added validation for at least one formula in calculator

app/models/calculator.rb

@@ -35,8 +35,15 @@ class Calculator < ApplicationRecord
   validates :en_name, :uk_name, presence: true
   validates :en_name, :uk_name, length: { minimum: 3, maximum: 50 }
   validates :slug, presence: true, uniqueness: true
+  validate :must_have_at_least_one_formula
 
   def self.ransackable_attributes(auth_object = nil)
     ["created_at", "id", "name", "preferable", "slug", "updated_at", "uuid"]
   end
+
+  def must_have_at_least_one_formula
+    return if formulas.present?
+
+    errors.add(:formulas, :not_present)
+  end
 end

app/views/account/calculators/partials/_form.html.erb

@@ -6,6 +6,7 @@
 
       <!-- formula input-->
       <div id="formulas" class="space-y-4">
+        <%= f.error_notification message: f.object.errors[:formulas].to_sentence if f.object.errors[:formulas].present? %>
         <%= f.simple_fields_for :formulas do |formula_fields| %>
           <%= render "account/calculators/partials/formula_fields", f: formula_fields %>
         <% end %>

config/locales/en/en.yml

@@ -641,6 +641,8 @@ en:
               too_long: "is too long (maximum is %{count} characters)"
               invalid: "contains invalid characters"
               taken: "has already been taken, please choose another one"
+            formulas:
+              not_present: "Calculator must have at least one formula present"
         category:
           attributes:
             name:

config/locales/uk/uk.yml

@@ -571,6 +571,8 @@ uk:
                 other: "занадто коротка (мінімум %{count} знаків)"
               taken: "вже викориcтовується, будь ласка, оберіть іншу"
               invalid: "містить неприпустимі символи"
+            formulas:
+              not_present: "Калькулятор має містити принаймні одну формулу"
         category:
           attributes:
             uk_name: &name_errors