Add Radio component with collection support

Radio buttons now bind to field values automatically:

  # Single radio
  Field(:gender).radio("male")  # checked when field.value == "male"

  # Collection of options
  Field(:status).radio("active", "inactive", "pending").each do |status|
    label do
      status.radio
      whitespace
      plain status.value.humanize
    end
  end

RadioCollection reuses OptionMapper for consistent option handling
across select, checkbox, and radio components.

Author: bradgessler

README.md

@@ -417,6 +417,19 @@ class SignupForm < Components::Form
       end
     end
 
+    # Radio groups: pass options to radio and iterate. Superform handles
+    # the name, value, and checked state automatically.
+    fieldset do
+      legend { "Status" }
+      Field(:status).radio(User.statuses).each do |status|
+        label do
+          status.radio
+          whitespace
+          plain status.value.humanize
+        end
+      end
+    end
+
     render button { "Submit" }
   end
 end

lib/superform/rails/components/radio.rb

@@ -0,0 +1,22 @@
+module Superform
+  module Rails
+    module Components
+      class Radio < Field
+        def initialize(field, value:, index: nil, attributes: {})
+          super(field, attributes: attributes)
+          @value = value
+          @index = index
+        end
+
+        def view_template(&)
+          input(type: :radio, **attributes)
+        end
+
+        def field_attributes
+          id = @index ? "#{dom.id}_#{@index}" : dom.id
+          { id: id, name: dom.name, value: @value, checked: field.value == @value }
+        end
+      end
+    end
+  end
+end

lib/superform/rails/field.rb

@@ -143,8 +143,15 @@ def file(*, **)
         input(*, **, type: :file)
       end
 
-      def radio(value, *, **)
-        input(*, **, type: :radio, value: value)
+      def radio(*args, **attributes)
+        if args.length == 1 && !args.first.is_a?(Array)
+          # Single scalar value: Field(:gender).radio("male")
+          Components::Radio.new(field, value: args.first, attributes: attributes)
+        else
+          # Collection of options: Field(:status).radio("active", "inactive", "pending")
+          # or Field(:status).radio(["active", "Active"], ["inactive", "Inactive"])
+          RadioCollection.new(field: field, options: args)
+        end
       end
 
       # Rails compatibility aliases

lib/superform/rails/radio_collection.rb

@@ -0,0 +1,35 @@
+module Superform
+  module Rails
+    class RadioCollection
+      include Enumerable
+
+      def initialize(field:, options:)
+        @field = field
+        @options = options
+        @index = 0
+      end
+
+      def each
+        OptionMapper.new(@options).each do |value, label|
+          @index += 1
+          yield RadioOption.new(field: @field, value: value, label: label, index: @index)
+        end
+      end
+    end
+
+    class RadioOption
+      attr_reader :value, :label
+
+      def initialize(field:, value:, label:, index:)
+        @field = field
+        @value = value
+        @label = label
+        @index = index
+      end
+
+      def radio(**attributes)
+        Components::Radio.new(@field, value: @value, index: @index, attributes: attributes)
+      end
+    end
+  end
+end

spec/superform/rails/components/radio_spec.rb

@@ -0,0 +1,89 @@
+RSpec.describe Superform::Rails::Components::Radio, type: :view do
+  describe 'single radio' do
+    let(:object) { double('object', gender: "male") }
+    let(:field) do
+      Superform::Rails::Field.new(:gender, parent: nil, object: object)
+    end
+
+    it 'renders a checked radio when value matches' do
+      html = render(field.radio("male"))
+      expect(html).to include('type="radio"')
+      expect(html).to include('name="gender"')
+      expect(html).to include('value="male"')
+      expect(html).to include('checked')
+    end
+
+    it 'renders an unchecked radio when value does not match' do
+      html = render(field.radio("female"))
+      expect(html).to include('value="female"')
+      expect(html).not_to include('checked')
+    end
+
+    it 'accepts custom attributes' do
+      html = render(field.radio("male", class: "radio-input"))
+      expect(html).to include('class="radio-input"')
+    end
+  end
+
+  describe 'radio collection' do
+    let(:object) { double('object', status: "active") }
+    let(:field) do
+      Superform::Rails::Field.new(:status, parent: nil, object: object)
+    end
+
+    it 'returns an enumerable' do
+      collection = field.radio("active", "inactive", "pending")
+      expect(collection).to respond_to(:each)
+    end
+
+    it 'yields options with value, label, and radio' do
+      options = field.radio(["active", "Active"], ["inactive", "Inactive"]).to_a
+      expect(options.length).to eq(2)
+      expect(options.first.value).to eq("active")
+      expect(options.first.label).to eq("Active")
+      expect(options.first).to respond_to(:radio)
+    end
+
+    it 'renders radios with correct checked state' do
+      html = ""
+      field.radio(["active", "Active"], ["inactive", "Inactive"], ["pending", "Pending"]).each do |status|
+        html += render(status.radio)
+      end
+
+      expect(html.scan(/type="radio"/).count).to eq(3)
+      expect(html.scan(/name="status"/).count).to eq(3)
+      expect(html.scan(/checked/).count).to eq(1)
+      expect(html).to match(/<input[^>]*value="active"[^>]*checked/)
+      expect(html).not_to match(/<input[^>]*value="inactive"[^>]*checked/)
+      expect(html).not_to match(/<input[^>]*value="pending"[^>]*checked/)
+    end
+
+    it 'generates unique IDs for each radio' do
+      html = ""
+      field.radio("active", "inactive").each do |status|
+        html += render(status.radio)
+      end
+
+      expect(html).to include('id="status_1"')
+      expect(html).to include('id="status_2"')
+    end
+
+    it 'works with the label pattern from the docs' do
+      html = ""
+      field.radio(["active", "Active"], ["inactive", "Inactive"]).each do |status|
+        # Simulating: label { status.radio; whitespace; plain status.value.humanize }
+        html += render(status.radio)
+      end
+
+      expect(html).to include('value="active"')
+      expect(html).to include('value="inactive"')
+      expect(html.scan(/checked/).count).to eq(1)
+    end
+
+    it 'works with single-value options (value used as label)' do
+      options = field.radio("active", "inactive").to_a
+      expect(options.first.value).to eq("active")
+      expect(options.first.label).to eq("active")
+    end
+  end
+end

spec/superform/rails/field_convenience_methods_spec.rb

@@ -25,7 +25,7 @@
     it { expect(field.color.type).to eq("color") }
     it { expect(field.search.type).to eq("search") }
     it { expect(field.file.type).to eq("file") }
-    it { expect(field.radio("male").type).to eq("radio") }
+    it { expect(field.radio("male")).to be_a(Superform::Rails::Components::Radio) }
   end
 
   describe "Rails compatibility aliases" do
@@ -56,8 +56,8 @@
     end
 
     it "handles radio button value parameter correctly" do
-      component = field.radio("female", class: "radio-input", data: { value: "f" })
-      expect(component.type).to eq("radio")
+      component = field.radio("female", class: "radio-input")
+      expect(component).to be_a(Superform::Rails::Components::Radio)
     end
   end
 end