# NoCMS Pages

## What's this?

This is a Rails engine with a basic functionality of flexible configurable menus stored in a database, so user can create, delete or modify menus via an admin interface (or at least through the databse). It's not attached to any particular CMS so you can use it freely within your Rails application without too much dependencies.

## How do I install it?

Right now there's no proper gem, although we have a couple of projects making extensive use of it.

To install it just put the repo in your Gemfile:

```ruby
gem "nocms-menus", git: 'git@github.com:simplelogica/nocms-menus.git'
```

And then import all the migrations:

```
rake no_cms_menus:install:migrations
```

And run them

```
rake db:migrate
```

And run the initializer:

```
rails g nocms:menus
```

This will create a `config/initializers/no_cms/menus.rb` file that contains all the configuration.

## How does it works?

NoCms Menus allow to create some "menu item" categories that can be attached to an object, an action/controller or an static url.

### Menu Kinds

This configuration is made through the `config/initializers/no_cms/menus.rb` file.

```ruby
NoCms::Menus.configure do |config|

  config.menu_kinds = {
    'page' => {
      object_class: Page,
    },
    'product' => {
      object_class: Product,
      object_name_method: :name,
      hidden: false
    },
    'products' => {
      action: 'products#index'
    },
    'fixed_url' => {
      external_url:  true
    }
  }

end

```

In the example there are four kinds of menu items: page, product, products and fixed_url. We will explain now each kind of menu item:

#### Object Classes: Page and Product

The first option for a menu_kind is to attach it to an ActiveRecord class. The `NoCms::Menus::MenuItem` class has a polymorphic relationship that will be used for each instance to retrieve the object attached.

The URL corresponding with that menu item will be the result of executing [polymorphic_path](http://api.rubyonrails.org/classes/ActionDispatch/Routing/PolymorphicRoutes.html#method-i-polymorphic_path) using the associated object.

```ruby
menu_item = NoCms::Menu::Item.create kind: :page, menuable: Page.first

show_submenu menu_item # => It will show (among other things) -> link_to(menu_item.name, main_app.polymorphic_path(Page.first))
```

There's one exception to this `polymorphic_path` solution. If the model defines a path method (maybe because it has a mechanism to customize paths) then this path method will be used.

```ruby
menu_item = NoCms::Menu::Item.create kind: :page, menuable: Page.first

Page.first.path # => an-awesome/customized/path-for-seo

show_submenu menu_item # => It will show (among other things) -> link_to(menu_item.name, Page.first.path)
```

The other option of the menu kind (`object_name_method`) is thought to be used by the admin interface (read about admin interface at the end of this README) and will allow to list all the instances from the attached ActiveRecord model.

#### Action: Products

Sometimes we need to attach a menu item not to an object, but to a controller and an action. The syntax used for the configuration is the standard one used by Rails in other places `namespace/controller#action`.

Following the previous configuration:

```ruby
menu_item = NoCms::Menu::Item.create kind: :products

show_submenu menu_item # => It will show (among other things) -> link_to(menu_item.name, main_app.url_for('products#index'))
```

#### External url

Other times we would like to link to a fixed url (normally an external one we can't automatically build from the Rails routes system). The external_url setting allows us to do it.

The external_url attribute from the model will be used to print the url.

```ruby
menu_item = NoCms::Menu::Item.create kind: :fixed_url

show_submenu menu_item # => It will show (among other things) -> link_to(menu_item.name, menu_item.external_url)
```

### Route sets

One of the most interesting of Rails features is the ability to modularize our apps using engines. This modularization allow us to have separate functionalities properly isolated in our application making code sharing and reusing quite easier (in fact, this nocms-menus gem is an engine!).

One concept coming from this isolation of routes is that of [Route Sets](http://guides.rubyonrails.org/engines.html#routes) that creates contexts of routes were helpers are defined (you can see an example in the previous link).

This mean that since our menu is normally displayed in all of our app we have to know in which RouteSet the `polymorphic_path` or `url_for` is being called.

If we are using routes from an engine (i.e. we are using routes from our news engine, which is mounted in the routes as :news) we need to configure the right route_set to be called:

```ruby
NoCms::Menus.configure do |config|

  config.menu_kinds = {
    'news' => {
      object_class: NewsEngine::NewsItem,
      route_set: :news
    }
  }

end
```

This way, the route set will be used:

```ruby
menu_item = NoCms::Menu::Item.create kind: :news, menuable: NewsEngine::NewsItem.first

show_submenu menu_item # => It will show (among other things) -> link_to(menu_item.name, news.polymorphic_path(NewsEngine::NewsItem.first))
```

If you look carefully you'll see that no main_app has been used to call the polymorphic path. Instead, the news route_set has been used.

`main_app` is only used when no route_set has been configured in the menu kind.

### Hidden menu items

Some menu items are not to be shown. As an example, we can imagine a menu `Events` pointing to an action such as `events#index`. If we enter into an event and go the `events#show` action we may want to activate the `Events` menu but, since we are not in `events#index` it won't be activated.

Solution is to create another menu kind `Any Event` that points to `events#show`, but if we create a menu item of this kind and accidentally leave it published then we will try to write the event_path helper, but without any id, which lead to crash.

To prevent this behaviour and having to watch out that our menu items are correctly published we can use the `hidden` flag on the configuration to make that any menu item of that kind is never visible.

In our example:

```ruby
NoCms::Menus.configure do |config|

  config.menu_kinds = {
    'events' => {
      action: 'events#index'
    },
    'any_event' => {
      action: 'events#show',
      hidden: true
    }
  }

end
```

Default value of this hidden flag will be `false`.

## Menu Cache

### Rails fragment cache

An standard Rails fragment cache is used to store an static version of the menus. You can enable/disable this cache by setting the NoCms::Menus.cache_enabled setting on the initialize.

You can override this setting on every call to the menu helper by sending the `cache: true` option.

## Menu Helpers

Menus and menu items are Rails object, and you can do with them whatever you want (just take into account considerations about route sets, cache and how to show each kind of menu item). If you want to show your menu in your own customized way I would recommend you to take a look to the [Menu Helper file](https://github.com/simplelogica/nocms-menus/blob/master/app/helpers/no_cms/menus/menu_helper.rb).

However, you have some helpers ready to be used that show the menu as a nested list:

* *show_menu*: This helper displays the menu as a nested list (ul). It takes the uid for the menu to be displayed (if there's no menu with that uid it doesn't print anything). It also takes a lot of options that will be explained later.

* *show_submenu*: This helper display a branch of a menu starting from the menu_item passed as parameter. It's used to display a menu item and the whole tree of descendants

* *show_children_submenu*: This helper displays the descendant tree of a menu item without that menu item. Main purpose of this helper is to show a submenu for a section (i.e. I'm in this section, show me the  menu just for this section).

```ruby

show_menu 'missing-menu' # It doesn't show anything as the menu is missing

show_menu 'main'
# <ul>
#   <li> A
#     <ul>
#       <li>AA</li>
#       <li>AB</li>
#     </ul>
#   </li>
#   <li> B
#     <ul>
#       <li>BA</li>
#       <li>BB
#         <ul>
#           <li>BBA</li>
#         </ul>
#       </li>
#       <li>BC</li>
#     </ul>
#   </li>
# </ul>

show_submenu menu_item_a
# <li> A
#   <ul>
#     <li>AA</li>
#     <li>AB</li>
#   </ul>
# </li>

show_children_submenu menu_item_b
# <ul>
#   <li>BA</li>
#   <li>BB
#     <ul>
#       <li>BBA</li>
#     </ul>
#   </li>
#   <li>BC</li>
# </ul>
```

The options for the helpers:

* *menu_class*: Class for the menu ul. By default it's 'menu'
* *initial_cache_key*: Initial fragment for the menu cache key. This way you can make the menus dependant on something external.
* *current_class*: Class for the li's of the currently active items
* *with_children_class*: Class for the li's that have a submenu
* *active_menu_items*: Menu items will be activated automatically. If for any reason we need to force the activation of certain menu items you can use this option
* *depth*: The number of levels we want to display (maybe we don't want infinite recursive menus)
* *submenu_class*: Class for the ul submenus
* *submenu_id: An id to be assigned to the first submenu displayed.


## Where is the admin interface?

`nocms-menus` is a gem with the minimum dependencies and that includes the admin interface.

Main idea is that this gem can be used in a project with a Rails Admin, an Active Admin or a home made admin.

As soon as we started using this gem we started our own admin interface, which is contained in another gem [nocms-admin-menus](https://github.com/simplelogica/nocms-admin-menus) and you can use it.

If your project already has another standard admin interface such as Rails Admin and you manage to embed nocms-menus on it, please, let us know and we will make a note here giving you full credit for the development :)