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Decorating a Model using SimpleDelegator
Rails developers start by modifying their model information within the template.
<h1><%= "#{ @user.first_name } #{ @user.last_name }" %></h1>
<h3>joined: <%= @user.created_at.in_time_zone(current_user.timezone).strftime("%A, %d %b %Y %l:%M %p") %></h3>Clicking "Copy Code" button will copy the code into the clipboard - memory. Please paste(Ctrl+V) it in your destination. The code will get pasted. Happy coding from Wikitechy - ruby on rails tutorial - rails guides - ruby rails - rubyonrails - learn ruby on rails - team
- For models with a lot of data, this can quickly become cumbersome and lead to copy-pasting logic from one template to another.
- This example uses SimpleDelegator from the stdlib.
- All requests to a SimpleDelegator object are passed to the parent object by default. You can override any method with presentation logic, or you can add new methods that are specific to this view.
- SimpleDelegator provides two methods: __setobj__ to set what object is being delegated to, and __getobj__ to get that object.
class UserDecorator < SimpleDelegator
attr_reader :view
def initialize(user, view)
__setobj__ @user
@view = view
end
# new methods can call methods on the parent implicitly
def full_name
"#{ first_name } #{ last_name }"
end
# however, if you're overriding an existing method you need
# to use __getobj__
def created_at
Time.use_zone(view.current_user.timezone) do
__getobj__.created_at.strftime("%A, %d %b %Y %l:%M %p")
end
end
endClicking "Copy Code" button will copy the code into the clipboard - memory. Please paste(Ctrl+V) it in your destination. The code will get pasted. Happy coding from Wikitechy - ruby on rails tutorial - rails guides - ruby rails - rubyonrails - learn ruby on rails - team
- Some decorators rely on magic to wire-up this behavior, but you can make it more obvious where the presentation logic is coming from by initializing the object on the page.
<% user = UserDecorator.new(@user, self) %>
<h1><%= user.full_name %></h1>
<h3>joined: <%= user.created_at %></h3>Clicking "Copy Code" button will copy the code into the clipboard - memory. Please paste(Ctrl+V) it in your destination. The code will get pasted. Happy coding from Wikitechy - ruby on rails tutorial - rails guides - ruby rails - rubyonrails - learn ruby on rails - team
- By passing a reference to the view object into the decorator, we can still access all of the rest of the view helpers while building the presentation logic without having to include it.
- The view template is only concerned with inserting data into the page, and it is much more clear.