Class: ActiveRecord::Base

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

Direct Known Subclasses

Backlog, Estimate, Party, Period, Task, Work

Class Method Summary collapse

Class Method Details

.class_table_inheritance(options = {}) ⇒ Object



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# File 'lib/class_table_inheritance.rb', line 24

def class_table_inheritance(options = {})
  table_name = options[:subclass_table] || name.demodulize.tableize
  primary_key_name = options[:subclass_foreign_key] || "#{superclass.name.demodulize.underscore}_id"
  
  has_extra_columns_from(
                         :table => table_name, :foreign_key => primary_key_name,
                         :proxy_class_name => 'ExtraColumns',
  :proxy_class_belongs_to => self.name,
  :delegate_new_associations => true,
  :save_before_superclass_callbacks => true
  )
end

.find_with_default_eager_loading(*params) ⇒ Object



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# File 'lib/class_table_inheritance.rb', line 7

def find_with_default_eager_loading(*params)
  if default_eager_loading
    if params.last.is_a?(Hash)
      opts = params.last
    else
      opts = {}
      params.push(opts)
    end
    opts[:include] ||= []
    opts[:include] = [opts[:include]] unless opts[:include].is_a?(Array)
    opts[:include] += default_eager_loading
  end
  find_without_default_eager_loading(*params)
end

.has_extra_columns_from(options, &block) ⇒ Object



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# File 'lib/class_table_inheritance.rb', line 37

def has_extra_columns_from(options, &block)
  table_name = options[:table]
  primary_key_name = options[:foreign_key] || "#{name.demodulize.underscore}_id"
  
  proxy_class_name = options[:proxy_class_name] || "ExtraColumnsFor#{table_name.camelize}"
  proxy_class_namespace = (options[:proxy_class_namespace] || name).constantize
  proxy_symbol = "extra_columns_for_#{table_name}".to_sym
  
  proxy_class = proxy_class_namespace.const_get(proxy_class_name) rescue nil
  unless proxy_class
    proxy_class = proxy_class_namespace.const_set(proxy_class_name, Class.new(ActiveRecord::Base))    
    proxy_class.class_eval do
      set_table_name table_name
      set_primary_key primary_key_name
      def self.reloadable?; false; end
    end
    proxy_class.class_eval(&block) if block_given?
  end
  
  has_one_without_cti proxy_symbol, :class_name => proxy_class.name, :foreign_key => primary_key_name, :dependent => true
  
  if options[:save_before_superclass_callbacks] || true
    # We need the after_save filter for this association to run /before/ any other after_save's already registered on a superclass,
    # and before any after_creates or after_updates. This calls for some hackery:
    proxy_save_callback = @inheritable_attributes[:after_save].pop
    @inheritable_attributes[:after_create] ||= []
    @inheritable_attributes[:after_create].unshift(proxy_save_callback)
    @inheritable_attributes[:after_update] ||= []
    @inheritable_attributes[:after_update].unshift(proxy_save_callback)
  end
  
  # adds this to the class-inheritable array of default eager loads:
  self.default_eager_loading = [proxy_symbol] unless options[:default_eager_loading] == false
  
  class_eval <<-EOV
    alias_method :#{proxy_symbol}_old, :#{proxy_symbol}
    def #{proxy_symbol}
      #{proxy_symbol}_old or self.#{proxy_symbol} = #{proxy_class.name}.new
    end
    def save(*args)
      self.#{proxy_symbol} ||= #{proxy_class.name}.new
      super
    end
    # this doesn't happen automatically on update, so we'll make it:
    after_update {|record| record.#{proxy_symbol}.save }
    
    alias_method :write_attribute_super, :write_attribute
    def write_attribute(attr_name, attr_value)
      if self.class.columns.find {|c| c.name == attr_name}
        write_attribute_super(attr_name, attr_value)
      else
        self.#{proxy_symbol}.write_attribute(attr_name, attr_value)
      end
    end
      
    alias_method :old_attributes, :attributes
    def attributes
      all_attributes = old_attributes.update(self.#{proxy_symbol}.attributes)
      all_attributes.delete(#{proxy_class_name}.primary_key) if self.class.primary_key != #{proxy_class_name}.primary_key
      all_attributes
    end

    class << self
      alias_method :method_missing_super, :method_missing
      def method_missing(method_symbol, *parameters)
        if method_symbol.to_s =~ /^find_by_(.+)/
          attributes = $1.split('_and_')
          super_attributes = attributes & columns.map {|c| c.name}
          sub_attributes = attributes - super_attributes
          if super_attributes.size > 0
            # TODO (uwe): Only use super attributes first
            # then filter by sub_attributes
            method_missing_super(method_symbol, parameters)
          else
            #{proxy_class_name}.method_missing(method_symbol, parameters)
          end
        else
          method_missing_super(method_symbol, parameters)
        end
      end
      
      delegate :foreign_keys, :validates_uniqueness_of, {:to => #{proxy_class_name}}
    end
  EOV
  
  delegate_methods = proxy_class.column_names
  delegate_methods += proxy_class.column_names.map {|name| "#{name}=".to_sym }
  delegate_methods += proxy_class.column_names.map {|name| "#{name}?".to_sym }
  proxy_class.reflect_on_all_associations.each do |reflection|
    delegate_methods += case reflection.macro
    when :has_many, :has_and_belongs_to_many
      [reflection.name, "#{reflection.name}=".to_sym, "#{reflection.name.to_s.singularize}_ids=".to_sym]
    when :has_one
      [reflection.name, "#{reflection.name}=".to_sym, "build_#{reflection.name}".to_sym, "create_#{reflection.name}".to_sym]
    when :belongs_to
      [reflection.name, "#{reflection.name}=".to_sym, "#{reflection.name}?".to_sym, "build_#{reflection.name}".to_sym, "create_#{reflection.name}".to_sym]
    end
  end
  delegate *(delegate_methods << {:to => proxy_symbol})
  
  proxy_class.belongs_to(:base, :class_name => options[:proxy_class_belongs_to], :foreign_key => primary_key_name) if options[:proxy_class_belongs_to]
  
  if options[:delegate_new_associations]
    class_eval <<-EOV
      # associations on this subclass get added to the proxy class, and then the relevant methods delegated to the proxy object
      def self.belongs_to(name, *params)
        ExtraColumns.belongs_to(name, *params)
        delegate name, "\#{name}=".to_sym, "\#{name}?".to_sym, "build_\#{name}".to_sym, "create_\#{name}".to_sym, :to => :#{proxy_symbol}
      end

      def self.has_one(name, *params)
        ExtraColumns.has_one(name, *params)
        delegate name, "\#{name}=".to_sym, "build_\#{name}".to_sym, "create_\#{name}".to_sym, :to => :#{proxy_symbol}
      end

      def self.has_many(name, *params)
        ExtraColumns.has_many(name, *params)
        delegate name, "\#{name}=".to_sym, "\#{name.to_s.singularize}_ids=".to_sym, :to => :#{proxy_symbol}
      end

      def self.has_and_belongs_to_many(name, *params)
        ExtraColumns.has_and_belongs_to_many(name, *params)
        delegate name, "\#{name}=".to_sym, "\#{name.to_s.singularize}_ids=".to_sym, :to => :#{proxy_symbol}
      end
    EOV
  end
end