Implementing patterns in text input. Closes #193

lib/simple_form/inputs/string_input.rb

@@ -8,6 +8,7 @@ module SimpleForm
 
       def input
         input_html_options[:size]      ||= [limit, SimpleForm.default_input_size].compact.min
+        input_html_options[:pattern]   ||= pattern_validator if validate_pattern?
         if password? || SimpleForm.html5
           input_html_options[:type]    ||= input_type unless string?
         end
@@ -35,6 +36,20 @@ module SimpleForm
       def password?
         input_type == :password
       end
+
+      def validate_pattern?
+        return unless has_validators?
+
+        SimpleForm.html5 && SimpleForm.browser_validations && find_pattern_validator.present?
+      end
+
+      def pattern_validator
+        find_pattern_validator.options[:with].source
+      end
+
+      def find_pattern_validator
+        attribute_validators.find { |v| ActiveModel::Validations::FormatValidator === v }
+      end
     end
   end
 end

test/inputs_test.rb

@@ -323,6 +323,30 @@ class InputTest < ActionView::TestCase
     assert_select 'input[max=119]'
   end
 
+  test 'input should infer pattern from attributes when it is present' do
+    with_input_for @other_validating_user, :country, :string
+    assert_select 'input[pattern="\w+"]'
+  end
+
+  test 'input should infer pattern from attributes when it is present as a password' do
+    with_input_for @other_validating_user, :country, :password
+    assert_select 'input[pattern="\w+"]'
+  end
+
+  test 'input should not add pattern from attributes when html5 are turned off' do
+    swap SimpleForm, :html5 => false do
+      with_input_for @other_validating_user, :country, :password
+      assert_no_select 'input[pattern="\w+"]'
+    end
+  end
+
+  test 'input should not add pattern from attributes when browser validations are turned off' do
+    swap SimpleForm, :browser_validations => false do
+      with_input_for @other_validating_user, :country, :password
+      assert_no_select 'input[pattern="\w+"]'
+    end
+  end
+
   test 'input should have step value of any except for integer attribute' do
     with_input_for @validating_user, :age, :float
     assert_select 'input[step="any"]'

test/support/models.rb

@@ -177,6 +177,8 @@ class OtherValidatingUser < User
     :greater_than_or_equal_to => Proc.new { |user| user.age },
     :less_than_or_equal_to => Proc.new { |user| user.age + 100},
     :only_integer => true
+
+  validates_format_of :country, :with => /\w+/
 end
 
 class HashBackedAuthor < Hash