Generates additional wrapper class based on object + attribute name,

like `<div class='input string user_name'>`.

Closes #576

CHANGELOG.md

@@ -1,5 +1,10 @@
 ## 2.1.0.dev
 
+### enhancements
+  * Generates additional wrapper class based on object + attribute name.
+    ([@lucasmazza](https://github/lucasmazza))
+    Closes [#576](https://github.com/plataformatec/simple_form/issues/576).
+
 ### bug fix
   * Fix escaping issue in `label_input` component
   ([@allomov](https://github.com/allomov))

lib/simple_form/inputs/base.rb

@@ -82,6 +82,10 @@ def additional_classes
         @additional_classes ||= [input_type, required_class, readonly_class, disabled_class].compact
       end
 
+      def input_class
+        "#{object_name}_#{reflection_or_attribute_name}"
+      end
+
       private
 
       def add_size!
@@ -113,7 +117,7 @@ def nested_boolean_style?
 
       # Find reflection name when available, otherwise use attribute
       def reflection_or_attribute_name
-        reflection ? reflection.name : attribute_name
+        @reflection_or_attribute_name ||= reflection ? reflection.name : attribute_name
       end
 
       # Retrieve options for the given namespace from the options hash

lib/simple_form/wrappers/root.rb

@@ -24,7 +24,9 @@ def find(name)
 
       def html_classes(input, options)
         css = options[:wrapper_class] ? Array.wrap(options[:wrapper_class]) : @defaults[:class]
-        css += SimpleForm.additional_classes_for(:wrapper) { input.additional_classes }
+        css += SimpleForm.additional_classes_for(:wrapper) do
+          input.additional_classes + [input.input_class]
+        end
         css << (options[:wrapper_error_class] || @defaults[:error_class]) if input.has_errors?
         css << (options[:wrapper_hint_class] || @defaults[:hint_class]) if input.has_hint?
         css.compact

test/form_builder/wrapper_test.rb

@@ -11,6 +11,16 @@ class WrapperTest < ActionView::TestCase
     assert_no_select 'div.field_with_errors'
   end
 
+  test 'wrapper should add the attribute name class' do
+    with_form_for @user, :name
+    assert_select 'div.user_name'
+  end
+
+  test 'wrapper should add the association name class' do
+    with_form_for @user, :company
+    assert_select 'div.user_company'
+  end
+
   test 'wrapper should add error class for attribute with errors' do
     with_form_for @user, :name
     assert_select 'div.field_with_errors'
@@ -72,6 +82,7 @@ class WrapperTest < ActionView::TestCase
       assert_select 'form div.wrapper'
       assert_no_select 'div.required'
       assert_no_select 'div.string'
+      assert_no_select 'div.user_name'
     end
   end