Reach Attachments And Basic Metaprogramming

Reach Attachments And Some Metaprogramming, Too

The basic problem

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Need to be able to attach arbitrary attachments to various model objects Don’t want to have to create new models for every relationship

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Need to have multiple kinds of attachments on each model object

Basic Implementation •

Using attachment_fu as a base Basic Data Layout: •

attachment_fu stuff

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attachable_id & attachable_type (polymorphic belongs_to) relationship (the relationship between the main model object and the attachment)

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position - used for ordering

Things We Need

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Easily add relationships Easily add the attachments from the controller

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Easily create the input/view boxes on the view

The Interface •

Model: reach_single_attachment :relationship_name Controller: @model_obj.attach_relationship_name(par ams[:file_field_name])

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View: •

<%= file_field :file_field_name %>

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<%= link_to_attachment “View”, @model_obj.relationship_name %>

The Metaprogram

module ActiveRecord class Base def self.reach_single_attachment(relationship) has_one relationship, :as => :attachable, :class_name => "Attachment", :conditions => "relationship = '#{relationship}'", :dependent => :destroy define_method("attach_#{relationship}") do |file_field| if file_field.size > 0 new_relationship_obj = self.send("create_#{relationship}", :uploaded_data => file_field, :relationship => relationship.to_s) return new_relationship_obj end end end end end

Usage in Reach Models

cord::Base

nity_map reach_single_attachment :community_video re

Using Metaprogramming

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Allows you to generalize in wierd ways Allows you to automate common tasks

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Allows you to codify application-specific conventions