Fix required on belongs_to for rails 7.1+

lib/simple_form/helpers/validators.rb

@@ -21,7 +21,46 @@ def valid_validator?(validator)
       end
 
       def conditional_validators?(validator)
-        validator.options.include?(:if) || validator.options.include?(:unless)
+        if_condition = validator.options[:if]
+        unless_condition = validator.options[:unless]
+
+        return false if if_condition.nil? && unless_condition.nil?
+
+        conditional = false
+
+        if if_condition
+          conditions = Array(if_condition)
+          conditional = conditions.any? { |c| !resolve_if_condition(c) }
+        end
+
+        if !conditional && unless_condition
+          conditions = Array(unless_condition)
+          conditional = conditions.any? { |c| resolve_if_condition(c) }
+        end
+
+        conditional
+      # If evaluating the condition fails (e.g., the condition references a method
+      # the object doesn't have, or a callable with unexpected arity), fall back to
+      # treating the validator as conditional and skipping it.
+      rescue NoMethodError, ArgumentError
+        true
+      end
+
+      def resolve_if_condition(condition)
+        case condition
+        when Symbol
+          object.send(condition)
+        else
+          if condition.respond_to?(:call)
+            if condition.is_a?(Proc) && condition.arity == 0
+              condition.call
+            else
+              condition.call(object)
+            end
+          else
+            condition
+          end
+        end
       end
 
       def action_validator_match?(validator)

test/inputs/required_test.rb

@@ -82,20 +82,32 @@ class RequiredTest < ActionView::TestCase
   end
 
   # VALIDATORS :if :unless
-  test 'builder input does not be required when ActiveModel::Validations is included and if option is present' do
+  test 'builder input is required when if condition is present and evaluates to true' do
+    with_form_for @validating_user, :age
+    assert_select 'input.required[required]#validating_user_age'
+  end
+
+  test 'builder input is not required when if condition is present and evaluates to false' do
+    @validating_user.name = nil
     with_form_for @validating_user, :age
     assert_no_select 'input.required'
     assert_no_select 'input[required]'
     assert_select 'input.optional#validating_user_age'
   end
 
-  test 'builder input does not be required when ActiveModel::Validations is included and unless option is present' do
+  test 'builder input is not required when unless condition is present and evaluates to true' do
     with_form_for @validating_user, :amount
     assert_no_select 'input.required'
     assert_no_select 'input[required]'
     assert_select 'input.optional#validating_user_amount'
   end
 
+  test 'builder input is required when unless condition is present and evaluates to false' do
+    @validating_user.age = nil
+    with_form_for @validating_user, :amount
+    assert_select 'input.required[required]#validating_user_amount'
+  end
+
   # VALIDATORS :on
   test 'builder input is required when validation is on create and is not persisted' do
     @validating_user.new_record!