Eoraptor Extracts - "Prepares.rb" 6:24 AM, Feb 8th
Just a simple one to start off today - This is a piece of code I've reused quite a few times and it's really saved me a lot of coding time retyping the same thing. In essence, prepares is a single drop in file for rails that adds a few niceties - basically preparing a model instance (via find) and storing it in an instance variable.
For example, if you want to prepare the model Post in the current controller on a certain set of actions, you may use this -
prepares :post, :only => [:show, :edit, :update, :destroy, :publish]
You have :only and :except options which can be passed straight into the before filter it builds. Other options include:
- :instance_var - the alternative instance variable name to use
- :params_key - what params attribute to use
- :if - a string (same as ruby code) which will be called if passed in e.g. a method (:action_name) - it's eval'ed
- :model - An alternate model to use; can either be a class (on which to_s is called for the name) or a symbol e.g. :blog_post -> BlogPost
There are no tests / documentation for it other than this (it's something I need to work on) but it in use on this blog. Oh, if you pick up an error, let me know - I chopped out some parts of it at the last minute.
Using it
Just add prepares.rb to your lib subdirectory of rails with this code; then add:
include Prepares::ControllerMixin
to your application controller / whichever controllers you want to use it.
The Source
Use it, even if your name isn't Luke and it isn't "The Force".
# prepares.rb - Copyright Darcy R. Laycock, 2008
# http://blog.ninjahideout.com
# Use as you want but please keep this header up top.
module Prepares
module ControllerMixin
def self.included(parent)
parent.class_eval do
extend Prepares::ClassMethods
include Prepares::InstanceMethods
end
end
end
module ClassMethods
def prepares(name, opts = {})
raise ArgumentError unless opts.is_a?(Hash)
opts.assert_valid_keys(:instance_var, :model, :except, :only, :params_key, :if)
params_key = opts[:params_key] || :id
instance_var_name = "@#{(opts[:instance_var] || name).to_s.gsub(/^[@]+/, "")}"
conditionals = opts.delete(:if) || nil
pmodel = get_prepares_model(opts[:model] || name)
method_name = :"prepares_#{name.to_s.underscore}"
method = "def #{method_name}\n"
method << "if #{conditionals}\n" if conditionals
method << " #{instance_var_name} = #{pmodel}.find(params[:#{params_key}])\n"
method << " end\n" if conditionals
method << "end\n"
before_filter_opts = {}
before_filter_opts[:except] = opts[:except].to_a unless opts[:except].blank? || opts[:except].to_a.empty?
before_filter_opts[:only] = opts[:only].to_a unless opts[:only].blank? || opts[:only].to_a.empty?
class_eval do
before_filter method_name, before_filter_opts
end
self.class_eval method
end
private
def get_prepares_model(pmodel)
if pmodel.is_a?(Symbol)
return pmodel.to_s.classify
else
return pmodel.to_s
end
end
end
module InstanceMethods # if it needs to be included.
end
end
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