Add markdown field support through SimpleMDE

app/assets/javascripts/rails_admin/ra.widgets.coffee

@@ -171,6 +171,31 @@ $(document).on 'rails_admin.dom_ready', (e, content) ->
                 html = html.add(option)
               object_select.html(html)
 
+
+    # simplemde
+
+    goSimpleMDEs = ->
+      content.find('[data-richtext=simplemde]').not('.simplemded').each (index, domEle) ->
+        options = $(this).data('options')
+        instance_config = options.instance_config
+        new window.SimpleMDE($.extend(true, {
+          element: document.getElementById(this.id),
+          autosave: {
+            uniqueId: this.id
+          }
+        }, instance_config))
+        $(this).addClass('simplemded')
+
+    $editors = content.find('[data-richtext=simplemde]').not('.simplemded')
+    if $editors.length
+      if not window.SimpleMDE
+        options = $editors.first().data('options')
+        $('head').append('<link href="' + options['css_location'] + '" rel="stylesheet" media="all" type="text\/css">')
+        $.getScript options['js_location'], (script, textStatus, jqXHR) ->
+          goSimpleMDEs()
+      else
+        goSimpleMDEs()
+
     # ckeditor
 
     goCkeditors = ->

app/views/rails_admin/main/_form_simple_mde.haml

@@ -0,0 +1,8 @@
+:ruby
+  js_data = {
+    js_location: field.js_location,
+    css_location: field.css_location,
+    instance_config: field.instance_config
+  }
+
+= form.text_area field.method_name, field.html_attributes.reverse_merge(data: { richtext: 'simplemde', options: js_data.to_json }).reverse_merge({ value: field.form_value })

lib/rails_admin/config/fields/types/all.rb

@@ -25,6 +25,7 @@
 require 'rails_admin/config/fields/types/time'
 require 'rails_admin/config/fields/types/timestamp'
 require 'rails_admin/config/fields/types/color'
+require 'rails_admin/config/fields/types/simple_mde'
 require 'rails_admin/config/fields/types/ck_editor'
 require 'rails_admin/config/fields/types/code_mirror'
 require 'rails_admin/config/fields/types/wysihtml5'

lib/rails_admin/config/fields/types/simple_mde.rb

@@ -0,0 +1,33 @@
+require 'rails_admin/config/fields/base'
+
+module RailsAdmin
+  module Config
+    module Fields
+      module Types
+        class SimpleMDE < RailsAdmin::Config::Fields::Types::Text
+          # Register field type for the type loader
+          RailsAdmin::Config::Fields::Types.register(self)
+
+          # If you want to have a different SimpleMDE config for each instance
+          # you can override this option with these values: https://github.com/sparksuite/simplemde-markdown-editor#configuration
+          register_instance_option :instance_config do
+            nil
+          end
+
+          # Use this if you want to point to a cloud instance of the base SimpleMDE
+          register_instance_option :js_location do
+            "#{Rails.application.config.assets.prefix}/simplemde.min.js"
+          end
+
+          register_instance_option :css_location do
+            "#{Rails.application.config.assets.prefix}/simplemde.min.css"
+          end
+
+          register_instance_option :partial do
+            :form_simple_mde
+          end
+        end
+      end
+    end
+  end
+end

spec/integration/config/edit/rails_admin_config_edit_spec.rb

@@ -901,6 +901,18 @@ class HelpTest < Tableless
     end
   end
 
+  describe 'SimpleMDE Support' do
+    it 'adds Javascript to enable SimpleMDE' do
+      RailsAdmin.config Draft do
+        edit do
+          field :notes, :simple_mde
+        end
+      end
+      visit new_path(model_name: 'draft')
+      is_expected.to have_selector('textarea#draft_notes[data-richtext="simplemde"]')
+    end
+  end
+
   describe 'CKEditor Support' do
     it 'adds Javascript to enable CKEditor' do
       RailsAdmin.config Draft do

spec/rails_admin/config/fields/types/simple_mde_spec.rb

@@ -0,0 +1,32 @@
+require 'spec_helper'
+
+describe RailsAdmin::Config::Fields::Types::SimpleMDE do
+  describe 'asset locations' do
+    before do
+      @custom_prefix = '/foo'
+      @default_prefix = Rails.application.config.assets.prefix
+      Rails.application.config.assets.prefix = @custom_prefix
+      RailsAdmin.config FieldTest do
+        field :text_field, :simple_mde
+      end
+    end
+
+    after do
+      Rails.application.config.assets.prefix = @default_prefix
+    end
+
+    it 'allows custom assets prefix for js' do
+      expect(
+        RailsAdmin.config(FieldTest).fields.detect { |f| f.name == :text_field }.with(object: FieldTest.new).js_location[0..(@custom_prefix.length - 1)],
+      ).to eq @custom_prefix
+    end
+
+    it 'allows custom assets prefix for css' do
+      expect(
+        RailsAdmin.config(FieldTest).fields.detect { |f| f.name == :text_field }.with(object: FieldTest.new).css_location[0..(@custom_prefix.length - 1)],
+      ).to eq @custom_prefix
+    end
+  end
+
+  it_behaves_like 'a generic field type', :text_field, :simple_mde
+end