« dziesig

Dynamic, Role-based Main Menu

Posted by dziesig.

I have a demo site for this recipe that I posted to github. Keep in mind that I have never used github before and am a relative new-comer to git itself.


This recipe implements a Dynamic Main Menu whose contents are a function of the site’s models and the User’s Role(s), with each User potentially having both Primary and Secondary Roles.

<bs> Background: My daughter is a successful Real Estate Broker here in Florida. <brag>She has degrees in Russian, French, Marketing and Computer Science.</brag> Together we collaborated on a Back Office Intranet originally implemented in Ruby-on-Rails (1.2 if I recall correctly). The menu system on that website was hard-coded to allow any given user to choose between two potential modes. For example, the Broker is also an Agent with different needs for each role. We had multiple roles:

   *   Administrator (me)
   *   Broker (my daughter)
   *   Reviewer (new for the Hobo version)
   *   Agent (my daughter plus many others)
   *   InactiveAgent (few)
   *   Unassigned (needed as a place holder).

The design called for a main menu with the following tabs:

   *   Home
   *   ModeSelect (caption is based on user's alternate role)
   *   Yada 1 (Required place-holder, never visible)
   *   Yada 2 (Broker-specific)
   *   Yada 10 (Agent-specific)
   *   Yada 20 (Reviewer-specific)
   *   Yada 32 (it's a big site with many functions/data).

After a really helpful tip from kevinpfromnm, which eliminated a lot of redundant editing between migrations, and which serendipitously improved the appearance of menus whose owners had primary and secondary roles, the menu design became:

   *   ModeSelect (caption is based on user's alternate role, if any)
       <extra space>
   *   Home
   *   Yada 1 (Required place-holder, never visible)
   *   Yada 2 (Broker-specific)
   *   Yada 10 (Agent-specific)
   *   Yada 20 (Reviewer-specific)
   *   Yada 32 (it's a big site with many functions/data).

The admin menu was:

   *   Home
   *   Permissions
   *   Roles
   *   Users

The formats of these menus can be seen in the attached images (once someone tells me where the link is hint, it is not the words “Upload image” on the left aside). In the meanwhile, the images are in the github repository noted above under the doc directory.

If all of the tabs on the main menu were visible simultaneously, there would be no room “above the fold” for application data.
Also, there are things that the Broker/Administrator can do that we didn’t want Agents know was possible.

My original Hobo design (or lack thereof) used a hard-coded main menu that (like its Rails predecessor) was getting very hard to maintain.

I took a step back (figuratively) and looked at what Hobo supplied in a “plain-vanilla” site with the intent of using dryml to extend it and map the main menu to the permission/role system. </bs>

The setup wizard choices need invite-only/email-invitation so the admin can set user’s roles in this recipe. There may be other ways for the administrator to setup the restricted attributes of users (specifically the user’s role that only admin can change) but I haven’t tried to find them.

    hobo new DynamicMainMenu

    cd DynamicMainMenu

I found this permission/role implementation somewhere but I can’t remember where. With a few mods to the original it works fine here.

    hobo g model permission_role
    hobo g resource admin::permission name:string description:string
    hobo g resource admin::role name:string description:string

This will populate the menu with some items.

    hobo g resource test_with_space name:string
    hobo g resource yada1  name:string
    hobo g resource yada2  name:string
    hobo g resource yada3  name:string
    hobo g resource yada4  name:string
    hobo g resource yada5  name:string
    hobo g resource yada6  name:string
    hobo g resource yada7  name:string
    hobo g resource yada8  name:string
    hobo g resource yada9  name:string
    hobo g resource yada10 name:string
    hobo g resource yada11 name:string
    hobo g resource yada12 name:string
    hobo g resource yada13 name:string
    hobo g resource yada14 name:string
    hobo g resource yada15 name:string
    hobo g resource yada16 name:string
    hobo g resource yada17 name:string
    hobo g resource yada18 name:string
    hobo g resource yada19 name:string
    hobo g resource yada20 name:string
    hobo g migration

At this point, you can start the app and see what happens when you have a lot of menu items. Note that the White Current tab impacts those below it.

Edit application.css

    /* Fixes the over-sized current tab */
    .page-header .navigation.main-nav li.current a {
      color: #222;
      background: url(../images/30-DBE1E5-FCFEF5.png) repeat-x #FCFEF5;
    /* reduces size of the development-mode dryml file names */
    /* Note, this comes from a mod I made to the hobo templates */
    /* It is not necessary without my mods, but is present in the demo */
      font-size: 9px;

Refresh the page and the White current tab height returns to the default of the other tabs and the menu behaves normally.

edit role.rb

    fields do
      name        :string, :unique, :index
      description :string
    has_many :users;
    has_many :permissions, :through => :permission_roles, :accessible => true
    has_many :permission_roles, :dependent => :destroy
    # --- Permissions --- #

edit permission.rb

    fields do
      name        :string, :unique, :index
      description :string
    has_many :roles, :through => :permission_roles, :accessible => true
    has_many :permission_roles, :dependent => :destroy
    # --- Permissions --- #

edit permission_role.rb

    fields do
    belongs_to :role
    belongs_to :permission
    def name
      if !role.nil? && !permission.nil?
        role.name + ' ' + permission.name
        '<undefined>' # just in case
    # --- Permissions --- #

hobo g migration

edit user.rb

    fields do
      name          :string, :required, :unique
      email_address :email_address, :login => true, :required => true, :unique => true
      administrator :boolean, :default => false
      use_secondary_role 	:boolean, :default => false #when true, user assumes secondary role
    belongs_to  :primary_role, :class_name => "Role"
    belongs_to  :secondary_role, :class_name => "Role"
    delegate    :permissions, :to => :role
    def role
      if self.use_secondary_role?
    def alternate_role
      if self.use_secondary_role?
    def toggle_mode
      self.use_secondary_role = !self.use_secondary_role
    # This gives admin rights and an :active state to the first sign-up.

< ….. snip ….. >

    alias_method_chain :new_password_required?, :invite_only
    # set default roles to Unassigned
    before_save do |user|
      self.primary_role_id = 6 if self.primary_role.nil?
      self.secondary_role_id = 6 if self.secondary_role.nil?
    # --- Signup lifecycle --- #

< ….. snip ….. >

    # Roles, Permissions, has_multiple_roles
      def method_missing(method_id, *args)
        if match = matches_dynamic_role_check?(method_id)
          tokenize_roles(match.captures.first).each do |check|
            if self.role.name.downcase == check
              return true
          return false
        elsif match = matches_dynamic_perm_check?(method_id)
          if !permissions.nil? 
            result = permissions.find_by_name(match.captures.first)
            return result
      def has_multiple_roles?
        if self.secondary_role != nil
          return self.secondary_role != self.primary_role unless self.secondary_role.name == 'Unassigned'
      def matches_dynamic_role_check?(method_id)
      def tokenize_roles(string_to_split)
      def matches_dynamic_perm_check?(method_id)
        result = /^can([a-zA-Z]\w*)\?$/.match(method_id.to_s)

hobo g migration

edit users_controller.rb

      < ..... snip ..... >
      def toggle
        redirect_to "#{base_url}/"

edit routes.rb

      match 'search' => 'front#search', :as => 'site_search'
      match 'user/toggle' => 'users#toggle'
      # The priority is based upon order of creation:
      < ..... snip ..... >

      # Sample resource route within a namespace:
      #   namespace :admin do
      #     # Directs /admin/products/* to Admin::ProductsController
      #     # (app/controllers/admin/products_controller.rb)
      #     resources :products
      #   end
      namespace :admin do
        resources :roles
        resources :permissions

Now for some DRYML magic (there may be a DRYer way for some of this, but it works for me). Create the file:


      The extension of nav-item implements an interface to the
      Permission/Role subsystem such that a positive permission in the
      form of AccessMenuItem will show the <nav-item> associated with 
      MenuItem (Use caution, the rails convention implies singular names,
      I've already been burnt using the permission "AccessStreetTypes" 
      which should have been "AccessStreetType") -->
    <extend tag="nav-item">
      <% body = parameters.default
         body = h(this.to_s) if body.blank?
         name ||= body.gsub(/<.*?>/, '').strip
         show_it = !(current_user.class == Guest)
        if show_it
          show_it = (name == 'Home') || 
                    (name == 'Permissions') || 
                    (name == 'Roles') || 
                    (name == 'Users') || 
                    (name.include?(' Mode'))
          if !show_it
            access = "current_user.canAccess" + this.to_s + "?"
            show_it = !(eval access).nil?
      <% if show_it %>
        <old-nav-item merge />
      <% else %>
        <old-nav-item merge style="display:none" />
      <% end %>

    <def tag="mode-nav-item">
      <% if current_user.respond_to?(:has_multiple_roles?) && current_user.has_multiple_roles?
        mode = "#{current_user.alternate_role} Mode" %> 
        <nav-item href="/user/toggle"><%= mode -%></nav-item>
      <% end %>

The following is only necessary if you absolutely need to re-arrange the menu. kevinpfromnm’s tip populates the menu automatically by <extending…> the <main-nav> tag.

Create the file app/views/taglibs/main_navigation.dryml

Copy the head of app/views/tablibs/auto/rapid/pages.dryml that contains the main menu into it, then make the noted change:

    <!-- ====== Main Navigation ====== -->
    <def tag="main-nav">
      <navigation class="main-nav" merge-attrs param="default">
        <nav-item href="#{base_url}/">Home</nav-item>
        <mode-nav-item/> <!-- ADD THIS IF YOU WANT TO HAVE MULTI-ROLE USERS -->
        <nav-item with="&TestWithSpace"><ht key="test_with_space.nav_item" count="100"><model-name-human count="100"/></ht></nav-item>
        <nav-item with="&Yada1"><ht key="yada1.nav_item" count="100"><model-name-human count="100"/></ht></nav-item>
        <nav-item with="&Yada2"><ht key="yada2.nav_item" count="100"><model-name-human count="100"/></ht></nav-item>
        <nav-item with="&Yada3"><ht key="yada3.nav_item" count="100"><model-name-human count="100"/></ht></nav-item>
        <nav-item with="&Yada4"><ht key="yada4.nav_item" count="100"><model-name-human count="100"/></ht></nav-item>
        <nav-item with="&Yada5"><ht key="yada5.nav_item" count="100"><model-name-human count="100"/></ht></nav-item>
        <nav-item with="&Yada6"><ht key="yada6.nav_item" count="100"><model-name-human count="100"/></ht></nav-item>
        <nav-item with="&Yada7"><ht key="yada7.nav_item" count="100"><model-name-human count="100"/></ht></nav-item>
        <nav-item with="&Yada8"><ht key="yada8.nav_item" count="100"><model-name-human count="100"/></ht></nav-item>
        <nav-item with="&Yada9"><ht key="yada9.nav_item" count="100"><model-name-human count="100"/></ht></nav-item>
        <nav-item with="&Yada10"><ht key="yada10.nav_item" count="100"><model-name-human count="100"/></ht></nav-item>
        <nav-item with="&Yada11"><ht key="yada11.nav_item" count="100"><model-name-human count="100"/></ht></nav-item>
        <nav-item with="&Yada12"><ht key="yada12.nav_item" count="100"><model-name-human count="100"/></ht></nav-item>
        <nav-item with="&Yada13"><ht key="yada13.nav_item" count="100"><model-name-human count="100"/></ht></nav-item>
        <nav-item with="&Yada14"><ht key="yada14.nav_item" count="100"><model-name-human count="100"/></ht></nav-item>
        <nav-item with="&Yada15"><ht key="yada15.nav_item" count="100"><model-name-human count="100"/></ht></nav-item>
        <nav-item with="&Yada16"><ht key="yada16.nav_item" count="100"><model-name-human count="100"/></ht></nav-item>
        <nav-item with="&Yada17"><ht key="yada17.nav_item" count="100"><model-name-human count="100"/></ht></nav-item>
        <nav-item with="&Yada18"><ht key="yada18.nav_item" count="100"><model-name-human count="100"/></ht></nav-item>
        <nav-item with="&Yada19"><ht key="yada19.nav_item" count="100"><model-name-human count="100"/></ht></nav-item>
        <nav-item with="&Yada20"><ht key="yada20.nav_item" count="100"><model-name-human count="100"/></ht></nav-item>

Notice that I re-arranged the Yada’s so they were in numeric order, not alphanumeric order. I did this only to be sure that we were NOT using the rapid-generated menu. Using the extended <main-nav> tag will return them to the original alphanumeric order.

Edit application.dryml

    <include src="taglibs/auto/rapid/forms"/>
    <include src="taglibs/nav_item"/>
    <include src="taglibs/main_navigation"/> <!-- only if you used the 
    <set-theme name="clean"/>

End of the “don’t do this unless…” section

kevinpfromnm’s tip. Create the file app/views/taglib/front_site.dryml:

    <include src="rapid" plugin="hobo"/>

    <include src="taglibs/auto/rapid/cards"/>
    <include src="taglibs/auto/rapid/pages"/>
    <include src="taglibs/auto/rapid/forms"/>

    <set-theme name="clean"/>

    <extend tag="main-nav">
      <navigation class="main-nav" merge-attrs param="default">
      <old-main-nav merge-attrs/>

At this time, if you restart the app and refresh your browser, you will see a very empty main menu

Now to populate the roles and permissions.

Login as the administrator (first user). In the gitHub demo site, the admin email is a@a.com with ‘Password’ as the password (all users of the demo site have ‘Password’ as their passwords).

Select the Admin link to get to the Admin sub-site.

Select the Roles tab on the menu and start adding Roles. In the demo site they are (in descending capability order):

  • Administrator
  • Broker
  • Reviewer
  • Agent
  • InactiveAgent
  • Unassigned « note this is hard-coded in user.rb as the 6th item.

You do not have to add permissions at this time. You do not have to order the entries except, for now, the 6th entry is the initialization value when users are created (I’ll fix that soon, I hope).

Select the Permissions tab on the menu and start adding menu permissions. Note that menu permissions start with Access and contain the SINGULAR name of the associated model.

Thus in the demo site,

   *  AccessYada1
   *      .
   *      .
   *      .
   *  AccessYada20

map to each of the dummy model menu tabs, even though the tabs are captioned Yada1s, …, Yada20s.

In my real-estate app, I use the locales to re-caption the menu tabs (this works even if you only use a single language, I implement en and es so it is not much of an additional hardship) just because the model names don’t necessarily map to concise labels.

Let’s add some permissions to the roles.

Select the Roles tab on the menu and map permissions to each role as you like.

I entered some pseudo-random associations in the demo site.

Now add some users with various roles. Since I have not setup the email for the demo site, you will have to look in the terminal output for the email message and manually copy the link for the invitation acceptance, as in:

    Sent mail to betty@broker.org (711ms)
    Date: Sun, 17 Apr 2011 21:18:20 -0400
    From: no-reply@
    To: betty@broker.org
    Message-ID: <4dab915cceea9_546d25615c84186cc@development.mail>
    Subject: Invitation to Dynamic Main Menu
    Mime-Version: 1.0
    Content-Type: text/html;
    Content-Transfer-Encoding: 7bit
    Betty Broker,
    You have been invited to join Dynamic Main Menu. If you wish to accept, please click on the following link
    Thank you,
    The Dynamic Main Menu team.

As soon as you issue the invitation (in the real world), edit the new user and assign appropriate roles. If you don’t, and the new user is fast enough, she will encounter the situation where her roles are unassigned and she can’t do anything.

Play with the demo site and you can see how the dynamics work. The Broker and Reviewer both have alternate roles as Agents so the tab immediately to the left of Home allows them to toggle to the mode displayed on the tab.

Note also that the permission system is not limited to the AccessMenuItem function. In my real-estate app, I have fine-grained permissions that enable/limit each role’s ability to (for example) view or modify other user’s data. The broker, in broker mode, can edit everyone’s profiles; in agent mode, she can only edit her own profile. The permissions, in this case are:

EditAllProfiles – associated code: current_user.canEditAllProfiles?

EditOwnProfile – associated code: current_user.canEditOwnProfile?

in the absence of either of these permissions, the user can not even edit her own profile.

Many thanks to kevinpfromnm for tip on extending the main-nav tag.

One last comment. If I were starting over, I would change the name of the Administrator role to something different to avoid confusion with the hobo user’s administrator boolean. For me this is more of a political issue; the name could be easily changed by editing the Role, but the rest of the staff is accustomed to it, (backwards compatibility with the rails app where it did not conflict), so I’m stuck with it (unless I just do it).

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