Module: ActsAsLookupClassMethods

Defined in:
lib/acts_as_lookup.rb

Overview

contains methods and logic to be added to classes that call the acts_as_lookup method

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.extended(klass) ⇒ Object 



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# File 'lib/acts_as_lookup.rb', line 5

def self.extended(klass)
  klass.send(:instance_variable_set, :@acts_as_lookup_options, nil)
  klass.send(:instance_variable_set, :@acts_as_lookup_by_id, {})
  klass.send(:instance_variable_set, :@acts_as_lookup_by_name, {})
  klass.send(:instance_variable_set, :@acts_as_lookup_initialized, false)
  klass.send(:instance_variable_set, :@acts_as_lookup_values, [])
end

Instance Method Details

#acts_as_lookup_add_query_method(lookup_name) ⇒ Object

adds an instance method of the form [lookup_value_name]? to check the identity of a lookup object



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# File 'lib/acts_as_lookup.rb', line 148

def acts_as_lookup_add_query_method(lookup_name)
  method_name = "#{get_method_name(lookup_name)}?"
  if respond_to?(method_name.to_sym)
    raise "Cannot create method '#{method_name}?' to #{self.inspect} " +
          "as it conflicts with existing method with same name"
  end

  define_method(method_name) { self.name == lookup_name }
end

#acts_as_lookup_add_shortcut(name) ⇒ Object

adds a class method to access a particular lookup value via a shortcut method

FUTURE: will allow for any column to be used here; for now, hardcoded

to lookup by name



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# File 'lib/acts_as_lookup.rb', line 135

def acts_as_lookup_add_shortcut(name)
  method_name = get_method_name(name)
  if respond_to?(method_name.to_sym)
    raise "Cannot create method '#{method_name}' to #{self.inspect} " +
          "as it conflicts with existing method with same name"
  end

  instance_eval "def #{method_name}; self.lookup_by_name '#{name}'; end"
end

#acts_as_lookup_fetch_values ⇒ Object

fetches existing records from the db and merges them into the cached values only called if :sync_with_db option is true

FUTURE: if this gem is to be used outside of a Rails’ ActiveRecord::Base descendant, will need to allow calling class to specify an alternative implementation (maybe add a config value that specifies a method to call)



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# File 'lib/acts_as_lookup.rb', line 81

def acts_as_lookup_fetch_values
  @acts_as_lookup_values = self.all
  self.acts_as_lookup_refresh_caches
end

#acts_as_lookup_initialize ⇒ Object

initialize the current lookup class for lookup use if it isn’t already

NOTE: early edition of this gem assumes id, name columns. FUTURE will allow

more flexibility through configuration



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# File 'lib/acts_as_lookup.rb', line 43

def acts_as_lookup_initialize
  Thread.exclusive do
    # double-check in case of race condition in calling code
    unless self.acts_as_lookup_initialized?
      if acts_as_lookup_options[:sync_with_db]
        acts_as_lookup_fetch_values
        if acts_as_lookup_options[:write_to_db]
          acts_as_lookup_write_missing_values
        end
      else
        @acts_as_lookup_values = acts_as_lookup_options[:values]
        self.acts_as_lookup_refresh_caches
      end

      @acts_as_lookup_initialized = true
    end

    # FUTURE: allow for a different column to be used for generating class
    #         accessor methods
    @acts_as_lookup_by_name.each_pair do |name,val|
      if acts_as_lookup_options[:add_query_methods]
        self.acts_as_lookup_add_query_method name
      end
      self.acts_as_lookup_add_shortcut name
    end

  end
end

#acts_as_lookup_initialized? ⇒ Boolean

check if the current lookup class has been initialized for lookup use

Returns:

  • (Boolean) 


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# File 'lib/acts_as_lookup.rb', line 33

def acts_as_lookup_initialized?
  @acts_as_lookup_initialized
end

#acts_as_lookup_options ⇒ Object 



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# File 'lib/acts_as_lookup.rb', line 16

def acts_as_lookup_options
  @acts_as_lookup_options
end

#acts_as_lookup_options=(options) ⇒ Object 



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# File 'lib/acts_as_lookup.rb', line 13

def acts_as_lookup_options=(options)
  @acts_as_lookup_options = options
end

#acts_as_lookup_refresh_caches ⇒ Object

updates the lookup cache hashes from @@acts_as_lookup_values



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# File 'lib/acts_as_lookup.rb', line 119

def acts_as_lookup_refresh_caches
  # FUTURE: this will get cleaned up, and will dynamically select which
  #         columns to establish lookup caches for.
  @acts_as_lookup_values.each do |val|
    @acts_as_lookup_by_id.merge!(val.id => val) unless @acts_as_lookup_by_id.include?(val.id)
    @acts_as_lookup_by_name.merge!(val.name => val) unless @acts_as_lookup_by_name.include?(val.name)
  end
end

#acts_as_lookup_write_missing_values ⇒ Object

writes any missing values to the db only called if :sync_with_db and :write_to_db options are both true

NOTE: does NOT overwrite any values found in the db, so it is possible for

the values specified in the class to be superceded by values in the
database



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# File 'lib/acts_as_lookup.rb', line 94

def acts_as_lookup_write_missing_values
  # FUTURE: if :ids aren't provided, use the uniqueness_column to determine
  #         which values are missing from existing caches
  acts_as_lookup_options[:values].each do |val|
    next if @acts_as_lookup_by_id.include?(val[:id])

    # bypass attr_accessible protection, assign attributes one-by-one
    new_val = self.new
    val.each_pair do |attr,value|
      setter = "#{attr.to_s}=".to_sym
      if new_val.respond_to?(setter)
        new_val.send(setter, value)
      end
    end
    new_val.save!

    @acts_as_lookup_values << new_val
  end

  self.acts_as_lookup_refresh_caches
end

#lookup_by_id(id) ⇒ Object

FUTURE: allow for dynamically specifying which columns can be used for

cache lookups



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# File 'lib/acts_as_lookup.rb', line 23

def lookup_by_id(id)
  @acts_as_lookup_by_id[id]
end

#lookup_by_name(name) ⇒ Object 



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# File 'lib/acts_as_lookup.rb', line 26

def lookup_by_name(name)
  @acts_as_lookup_by_name[name]
end