simple_form.rb for semantic ui

_form.html.erb

<%= f.input :email,
            wrapper: :semantic_icon_input,
            label: false,
            required: true,
            placeholder: t('users.form.placeholder.email'),
            left_icon: 'user' %>

icons_component.rb

module SimpleForm
  module Components
    # Needs to be enabled in order to do automatic lookups
    module Icons
      # Name of the component method
      def left_icon(wrapper_options = nil)
        options.merge!(left_icon_html: { class: options[:left_icon].to_s.html_safe }) if options[:left_icon].present?
        @left_icon ||= begin
          '' if options[:left_icon].present?
        end
      end

      # Name of the component method
      def right_icon(wrapper_options = nil)
        options.merge!(right_icon_html: { class: options[:right_icon].to_s.html_safe }) if options[:right_icon].present?
        @right_icon ||= begin
          '' if options[:right_icon].present?
        end
      end

      def has_left_icon?
        not left_icon.nil?
      end

      def has_right_icon?
        not right_icon.nil?
      end
    end
  end
end

SimpleForm::Inputs::Base.send(:include, SimpleForm::Components::Icons)

labels_component.rb

module SimpleForm
  module Components
    # Needs to be enabled in order to do automatic lookups
    module Labels
      # Name of the component method
      def left_label(wrapper_options = nil)
        @left_label ||= begin
          options[:left_label].to_s.html_safe if options[:left_label].present?
        end
      end

      # Name of the component method
      def right_label(wrapper_options = nil)
        @right_label ||= begin
          options[:right_label].to_s.html_safe if options[:right_label].present?
        end
      end

      def has_left_label?
        left_label.present?
      end

      def has_right_label?
        right_label.present?
      end
    end
  end
end

SimpleForm::Inputs::Base.send(:include, SimpleForm::Components::Labels)

simple_form.rb

# Use this setup block to configure all options available in SimpleForm.
SimpleForm.setup do |config|
  # Wrappers are used by the form builder to generate a
  # complete input. You can remove any component from the
  # wrapper, change the order or even add your own to the
  # stack. The options given below are used to wrap the
  # whole input.
  config.wrappers :default, class: :input,
                  hint_class: :field_with_hint, error_class: :field_with_errors do |b|
    ## Extensions enabled by default
    # Any of these extensions can be disabled for a
    # given input by passing: `f.input EXTENSION_NAME => false`.
    # You can make any of these extensions optional by
    # renaming `b.use` to `b.optional`.

    # Determines whether to use HTML5 (:email, :url, ...)
    # and required attributes
    b.use :html5

    # Calculates placeholders automatically from I18n
    # You can also pass a string as f.input placeholder: "Placeholder"
    b.use :placeholder

    ## Optional extensions
    # They are disabled unless you pass `f.input EXTENSION_NAME => true`
    # to the input. If so, they will retrieve the values from the model
    # if any exists. If you want to enable any of those
    # extensions by default, you can change `b.optional` to `b.use`.

    # Calculates maxlength from length validations for string inputs
    b.optional :maxlength

    # Calculates pattern from format validations for string inputs
    b.optional :pattern

    # Calculates min and max from length validations for numeric inputs
    b.optional :min_max

    # Calculates readonly automatically from readonly attributes
    b.optional :readonly

    ## Inputs
    b.use :label_input
    b.use :hint, wrap_with: { tag: :span, class: :hint }
    b.use :error, wrap_with: { tag: :span, class: :error }

    ## full_messages_for
    # If you want to display the full error message for the attribute, you can
    # use the component :full_error, like:
    #
    # b.use :full_error, wrap_with: { tag: :span, class: :error }
  end


  config.wrappers :semantic, tag: 'div', class: 'field', error_class: 'error', hint_class: 'with_hint' do |b|
    b.use :html5
    b.use :placeholder
    b.use :label_input
    b.optional :maxlength
    b.optional :pattern
    b.optional :min_max
    b.use :error, wrap_with: { tag: 'div', class: 'ui red pointing above label error' }
    b.use :hint, wrap_with: { tag: 'div', class: 'hint' }
  end

  config.wrappers :semantic_icon_input, tag: 'div', class: 'field', error_class: 'error', hint_class: 'with_hint' do |b|
    b.use :html5
    b.use :label
    b.wrapper :icon_input_wrapper, tag: 'div', class: 'ui left icon input', error_class: 'error', hint_class: 'with_hint' do |bw|
      bw.use :placeholder
      bw.optional :maxlength
      bw.optional :pattern
      bw.optional :min_max
      bw.use :left_icon, wrap_with: { tag: :i, class: 'ui icon' }
      bw.use :input
      bw.use :right_icon, wrap_with: { tag: :i, class: 'ui icon' }
    end

    b.use :error, wrap_with: { tag: 'div', class: 'ui red pointing above label error' }
    b.use :hint, wrap_with: { tag: 'div', class: 'hint' }
  end

  config.wrappers :semantic_labeled_input, tag: 'div', class: 'field', error_class: 'error', hint_class: 'with_hint' do |b|
    b.use :html5
    b.use :label
    b.wrapper :labeled_input_wrapper, tag: 'div', class: 'ui both labeled input', error_class: 'error', hint_class: 'with_hint' do |bw|
      bw.use :placeholder
      bw.optional :maxlength
      bw.optional :pattern
      bw.optional :min_max
      bw.use :left_label, wrap_with: { tag: :div, class: 'ui label' }
      bw.use :input
      bw.use :right_label, wrap_with: { tag: :div, class: 'ui label' }
    end

    b.use :error, wrap_with: { tag: 'div', class: 'ui red pointing above label error' }
    b.use :hint, wrap_with: { tag: 'div', class: 'hint' }
  end

  config.wrappers :semantic_checkbox, tag: 'div', class: 'inline field', error_class: 'error', hint_class: 'with_hint' do |b|
    b.use :html5
    b.wrapper tag: 'div', class: 'ui checkbox' do |input|
      input.use :input
      input.wrapper tag: 'label' do |box|
      end
    end
    b.use :label
  end

  config.wrappers :semantic_checkbox_slider, tag: 'div', class: 'inline field', error_class: 'error', hint_class: 'with_hint' do |b|
    b.use :html5
    b.wrapper tag: 'div', class: 'ui slider checkbox' do |input|
      input.use :input
      input.wrapper tag: 'label' do |slide|
      end
    end
    b.use :label
  end

  config.wrappers :semantic_checkbox_toggle, tag: 'div', class: 'inline field', error_class: 'error', hint_class: 'with_hint' do |b|
    b.use :html5
    b.wrapper tag: 'div', class: 'ui toggle checkbox' do |input|
      input.use :input
      input.wrapper tag: 'label' do |slide|
      end
    end
    b.use :label
  end

  config.wrappers :semantic_radio_buttons, tag: 'div', class: 'grouped fields', error_class: 'error', hint_class: 'with_hint' do |b|
    b.use :html5
    b.optional :readonly

    b.use :label
    b.use :input
    b.use :error, wrap_with: { tag: 'span', class: 'help-block' }
    b.use :hint, wrap_with: { tag: 'p', class: 'help-block' }
  end

# The default wrapper to be used by the FormBuilder.
  config.default_wrapper = :semantic

# Define the way to render check boxes / radio buttons with labels.
# Defaults to :nested for bootstrap config.
#   inline: input + label
#   nested: label > input
  config.boolean_style = :inline

# Default class for buttons
  config.button_class = 'ui fluid large teal submit button'

# Method used to tidy up errors. Specify any Rails Array method.
# :first lists the first message for each field.
# Use :to_sentence to list all errors for each field.
  config.error_method = :first

# Default tag used for error notification helper.
  config.error_notification_tag = :div

# CSS class to add for error notification helper.
  config.error_notification_class = 'ui error message'

# ID to add for error notification helper.
# config.error_notification_id = nil

# Series of attempts to detect a default label method for collection.
# config.collection_label_methods = [ :to_label, :name, :title, :to_s ]

# Series of attempts to detect a default value method for collection.
# config.collection_value_methods = [ :id, :to_s ]

# You can wrap a collection of radio/check boxes in a pre-defined tag, defaulting to none.
  config.collection_wrapper_tag = :div

# You can define the class to use on all collection wrappers. Defaulting to none.
  config.collection_wrapper_class = 'field'

# You can wrap each item in a collection of radio/check boxes with a tag,
# defaulting to :span. Please note that when using :boolean_style = :nested,
# SimpleForm will force this option to be a label.
  config.item_wrapper_tag = :div

# You can define a class to use in all item wrappers. Defaulting to none.
  config.item_wrapper_class = 'ui radio checkbox'

# How the label text should be generated altogether with the required text.
  config.label_text = lambda { |label, required, explicit_label| "#{label} #{required}" }

# You can define the class to use on all labels. Default is nil.
# config.label_class = nil

# DEPRECATED: You can define the class to be used on all forms. Default is
# simple_form.
  config.form_class = ''

# You can define the default class to be used on forms. Can be overriden
# with `html: { :class }`. Defaulting to none.
  config.default_form_class = 'ui form'

# You can define which elements should obtain additional classes
# config.generate_additional_classes_for = [:wrapper, :label, :input]

# Whether attributes are required by default (or not). Default is true.
# config.required_by_default = true

# Tell browsers whether to use the native HTML5 validations (novalidate form option).
# These validations are enabled in SimpleForm's internal config but disabled by default
# in this configuration, which is recommended due to some quirks from different browsers.
# To stop SimpleForm from generating the novalidate option, enabling the HTML5 validations,
# change this configuration to true.
  config.browser_validations = false

# Collection of methods to detect if a file type was given.
# config.file_methods = [ :mounted_as, :file?, :public_filename ]

# Custom mappings for input types. This should be a hash containing a regexp
# to match as key, and the input type that will be used when the field name
# matches the regexp as value.
# config.input_mappings = { /count/ => :integer }

# Custom wrappers for input types. This should be a hash containing an input
# type as key and the wrapper that will be used for all inputs with specified type.
# config.wrapper_mappings = { string: :prepend }
  config.wrapper_mappings = {
    radio_buttons: :semantic_radio_buttons,
  }

# Namespaces where SimpleForm should look for custom input classes that
# override default inputs.
# config.custom_inputs_namespaces << "CustomInputs"

# Default priority for time_zone inputs.
# config.time_zone_priority = nil

# Default priority for country inputs.
# config.country_priority = nil

# When false, do not use translations for labels.
# config.translate_labels = true

# Automatically discover new inputs in Rails' autoload path.
# config.inputs_discovery = true

# Cache SimpleForm inputs discovery
# config.cache_discovery = !Rails.env.development?

# Default class for inputs
# config.input_class = nil

# Define the default class of the input wrapper of the boolean input.
  config.boolean_label_class = 'checkbox'

# Defines if the default input wrapper class should be included in radio
# collection wrappers.
  config.include_default_input_wrapper_class = true

  # Defines which i18n scope will be used in Simple Form.
  # config.i18n_scope = 'simple_form'
end