Using model validations to determine whether a field is required.

lib/simple_form/inputs/base.rb

@@ -49,6 +49,11 @@ module SimpleForm
       end
 
       def attribute_required?
+        klass = object.class
+        if defined? klass.validators_on
+          return options[:required] unless options[:required].nil?
+          return klass.validators_on(attribute_name).map {|validator| validator.kind}.include?(:presence)
+        end
         options[:required] != false
       end
 

test/components/label_test.rb

@@ -94,13 +94,27 @@ class LabelTest < ActionView::TestCase
     with_label_for @user, :created_at, :datetime
     assert_select 'label.datetime'
   end
+  
+  test 'label should obtain required from ActiveModel::Validations when it is included' do
+    with_label_for @validating_user, :name, :string
+    assert_select 'label.required'
+    with_label_for @validating_user, :status, :string
+    assert_select 'label.optional'
+  end
+  
+  test 'label should allow overriding required when ActiveModel::Validations is included' do
+    with_label_for @validating_user, :name, :string, :required => false
+    assert_select 'label.optional'
+    with_label_for @validating_user, :status, :string, :required => true
+    assert_select 'label.required'
+  end
 
-  test 'label should be required by default' do
+  test 'label should be required by default when ActiveModel::Validations is not included' do
     with_label_for @user, :name, :string
     assert_select 'label.required'
   end
 
-  test 'label should be able to disable required' do
+  test 'label should be able to disable required when ActiveModel::Validations is not included' do
     with_label_for @user, :name, :string, :required => false
     assert_no_select 'label.required'
   end

test/form_builder_test.rb

@@ -229,12 +229,26 @@ class FormBuilderTest < ActionView::TestCase
     assert_select 'span.error#cool', "can't be blank"
   end
 
-  test 'builder input should be required by default' do
+  test 'builder input should obtain required from ActiveModel::Validations when it is included' do
+    with_form_for @validating_user, :name
+    assert_select 'input.required#validating_user_name'
+    with_form_for @validating_user, :status
+    assert_select 'input.optional#validating_user_status'
+  end
+  
+  test 'builder input should allow overriding required when ActiveModel::Validations is included' do
+    with_form_for @validating_user, :name, :required => false
+    assert_select 'input.optional#validating_user_name'
+    with_form_for @validating_user, :status, :required => true
+    assert_select 'input.required#validating_user_status'
+  end
+  
+  test 'builder input should be required by default when ActiveModel::Validations is not included' do
     with_form_for @user, :name
     assert_select 'input.required#user_name'
   end
-
-  test 'builder input should allow disabling required' do
+  
+  test 'builder input should allow disabling required when ActiveModel::Validations is not included' do
     with_form_for @user, :name, :required => false
     assert_no_select 'input.required'
     assert_select 'input.optional#user_name'

test/support/models.rb

@@ -100,3 +100,8 @@ class User < OpenStruct
     }
   end
 end
+
+class ValidatingUser < User
+  include ActiveModel::Validations
+  validates :name, :presence => true
+end

test/test_helper.rb

@@ -55,6 +55,13 @@ class ActionView::TestCase
       :description => 'Hello!',
       :created_at => Time.now
     }.merge(options))
+    
+    @validating_user = ValidatingUser.new({
+      :id => 1,
+      :name => 'New in Simple Form!',
+      :description => 'Hello!',
+      :created_at => Time.now
+    }.merge(options))
   end
 
   def protect_against_forgery?
@@ -66,4 +73,5 @@ class ActionView::TestCase
   end
   alias :users_path :user_path
   alias :super_user_path :user_path
+  alias :validating_user_path :user_path
 end