Class: Curly::Presenter

Inherits:
Object
  • Object
show all
Defined in:
lib/curly/presenter.rb

Overview

A base class that can be subclassed by concrete presenters.

A Curly presenter is responsible for delivering data to templates, in the form of simple strings. Each public instance method on the presenter class can be referenced in a template. When a template is evaluated with a presenter, the referenced methods will be called with no arguments, and the returned strings inserted in place of the references in the template.

Note that strings that are not HTML safe will be escaped.

A presenter is always instantiated with a context to which it delegates unknown messages, usually an instance of ActionView::Base provided by Rails. See Curly::TemplateHandler for a typical use.

Examples

class BlogPresenter < Curly::Presenter
  presents :post

  def title
    @post.title
  end

  def body
    markdown(@post.body)
  end

  def author
    @post.author.full_name
  end
end

presenter = BlogPresenter.new(context, post: post)
presenter.author #=> "Jackie Chan"

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(context, options = {}) ⇒ Presenter

Initializes the presenter with the given context and options.

context - An ActionView::Base context. options - A Hash of options given to the presenter.



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# File 'lib/curly/presenter.rb', line 45

def initialize(context, options = {})
  @_context = context
  self.class.presented_names.each do |name|
    instance_variable_set("@#{name}", options.fetch(name))
  end
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(method, *args, &block) ⇒ Object (private)

Delegates private method calls to the current view context.

The view context, an instance of ActionView::Base, is set by Rails.



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# File 'lib/curly/presenter.rb', line 200

def method_missing(method, *args, &block)
  @_context.public_send(method, *args, &block)
end

Class Method Details

.available_methods ⇒ Object

A list of methods available to templates rendered with the presenter.

Returns an Array of Symbol method names.



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# File 'lib/curly/presenter.rb', line 128

def available_methods
  public_instance_methods - Curly::Presenter.public_instance_methods
end

.cache_key ⇒ Object

The cache key for the presenter class. Includes all dependencies as well.

Returns a String cache key.



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# File 'lib/curly/presenter.rb', line 172

def cache_key
  @cache_key ||= compute_cache_key
end

.dependencies ⇒ Object

The set of view paths that the presenter depends on.

Example

class Posts::ShowPresenter < Curly::Presenter
  version 2
  depends_on 'posts/comment', 'posts/comment_form'
end

Posts::ShowPresenter.dependencies
#=> ['posts/comment', 'posts/comment_form']

Returns a Set of String view paths.



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# File 'lib/curly/presenter.rb', line 145

def dependencies
  @dependencies ||= Set.new
end

.depends_on(*deps) ⇒ Object

Indicate that the presenter depends a list of other views.

deps - A list of String view paths that the presenter depends on.

Returns nothing.



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# File 'lib/curly/presenter.rb', line 154

def depends_on(*deps)
  dependencies.merge(deps)
end

.presenter_for_path(path) ⇒ Object 



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# File 'lib/curly/presenter.rb', line 121

def presenter_for_path(path)
  presenter_name_for_path(path).constantize
end

.presenter_name_for_path(path) ⇒ Object

The name of the presenter class for a given view path.

path - The String path of a view.

Examples

Curly::TemplateHandler.presenter_name_for_path("foo/bar")
#=> "Foo::BarPresenter"

Returns the String name of the matching presenter class.



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# File 'lib/curly/presenter.rb', line 117

def presenter_name_for_path(path)
  "#{path}_presenter".camelize
end

.version(version = nil) ⇒ Object

Get or set the version of the presenter.

version - The Integer version that should be set. If nil, no version

is set.

Returns the current Integer version of the presenter.



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# File 'lib/curly/presenter.rb', line 164

def version(version = nil)
  @version = version if version.present?
  @version || 0
end

Instance Method Details

#cache_duration ⇒ Object

The duration that the view should be cached for. Only relevant if ‘#cache_key` returns a non nil value.

If nil, the view will not have an expiration time set.

Examples

def cache_duration
  10.minutes
end

Returns the Fixnum duration of the cache item, in seconds, or nil if no

duration should be set.



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# File 'lib/curly/presenter.rb', line 83

def cache_duration
  nil
end

#cache_key ⇒ Object

The key that should be used to cache the view.

Unless ‘#cache_key` returns nil, the result of rendering the template that the presenter supports will be cached. The return value will be part of the final cache key, along with a digest of the template itself.

Any object can be used as a cache key, so long as it

  • is a String,

  • responds to #cache_key itself, or

  • is an Array of a Hash whose items themselves fit either of these criteria.

Returns the cache key Object or nil if no caching should be performed.



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# File 'lib/curly/presenter.rb', line 66

def cache_key
  nil
end

#method_available?(method) ⇒ Boolean

Whether a method is available to templates rendered with the presenter.

Templates can reference “variables”, which are simply methods defined on the presenter. By default, only public instance methods can be referenced, and any method defined on Curly::Presenter itself cannot be referenced. This means that methods such as ‘#cache_key` and #inspect are not available. This is done for safety purposes.

This policy can be changed by overriding this method in your presenters.

method - The Symbol name of the method.

Returns true if the method can be referenced by a template,

false otherwise.

Returns:

  • (Boolean) 


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# File 'lib/curly/presenter.rb', line 101

def method_available?(method)
  self.class.available_methods.include?(method)
end