Rails Contexts
A demonstration of polymorphic associations and dynamic context-setting through meta-programming in Rails. We use a generic CRUD environment modeled after a question-and-answer database with users, tags, questions, answers, comments, and votes.
Dynamic Contexts
Contexts are set dynamically:
def update
set_contexts
if @answer.update(answer_params)
redirect_to dyn_question_path(@context, @id, @answer.question), notice: 'Answer updated.'
else
render :edit
end
end
def set_contexts(array = default_contexts)
array.each do |ctxt|
if params["#{ctxt}_id".intern]
@context = ctxt
@id = params["#{ctxt}_id".intern]
return
end
end
@context = :none
end
Paths are organized by helpers:
def dyn_receiver(context, id, answer)
get_context(context,
user: -> { [User.find(id), answer] },
tag: -> { [Tag.find(id), answer] },
none: -> { answer }
)
end
def get_context(context, hash)
hash.each { |ctxt, lmbd| return lmbd.call if context == ctxt }
end
Polymorphism
Associations are polymorphic. Questions, answers, comments, and votes are all interpreted as items:
class Answer < ActiveRecord::Base
belongs_to :user
belongs_to :question
has_many :comments, as: :item
has_many :votes, as: :item
end
Contributing
- Fork it
- Create your feature branch (
git checkout -b my-new-feature) - Commit your changes (
git commit -am 'Add some feature') - Push to the branch (
git push origin my-new-feature) - Create new Pull Request