Class: DataMapper::Associations::ManyToMany::Relationship

Inherits:
OneToMany::Relationship show all
Extended by:
Chainable
Defined in:
lib/dm-core/associations/many_to_many.rb

Constant Summary collapse

OPTIONS = 
superclass::OPTIONS.dup << :through << :via

Instance Attribute Summary

Attributes inherited from Relationship

#child_properties, #child_repository_name, #instance_variable_name, #max, #min, #name, #options, #parent_properties, #parent_repository_name, #reader_visibility, #writer_visibility

Instance Method Summary collapse

Methods included from Chainable

chainable, extendable

Methods inherited from OneToMany::Relationship

#collection_for, #default_for, #get, #get_collection, #lazy_load, #set, #set_collection

Methods inherited from Relationship

#==, #child_model, #child_model?, #child_model_name, #eql?, #field, #get, #get!, #hash, #inverse, #loaded?, #parent_key, #parent_model, #parent_model?, #parent_model_name, #query_for, #relative_target_repository_name, #relative_target_repository_name_for, #set, #set!, #valid?

Methods included from Subject

#default?, #default_for

Methods included from DataMapper::Assertions

#assert_kind_of

Instance Method Details

#child_key ⇒ DataMapper::PropertySet Also known as: target_key

Returns a set of keys that identify the target model

Returns:



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# File 'lib/dm-core/associations/many_to_many.rb', line 15

def child_key
  return @child_key if defined?(@child_key)

  repository_name = child_repository_name || parent_repository_name
  properties      = child_model&.properties(repository_name)

  @child_key = if @child_properties
                 child_key = properties&.values_at(*@child_properties)
                 properties.class.new(child_key).freeze
               else
                 properties&.key
               end
end

#eager_load(source, other_query = nil) ⇒ ManyToMany::Collection

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Eager load the collection using the source as a base

Parameters:

  • source (Resource, Collection) —

    the source to query with

  • other_query (Query, Hash) (defaults to: nil) —

    optional query to restrict the collection

Returns:



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# File 'lib/dm-core/associations/many_to_many.rb', line 157

def eager_load(source, other_query = nil)
  # FIXME: enable SEL for m:m relationships
  source.model.all(query_for(source, other_query))
end

#finalize ⇒ self

Initialize the chain for “many to many” relationships

Returns:

  • (self) 


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# File 'lib/dm-core/associations/many_to_many.rb', line 128

def finalize
  through
  via
  self
end

#links ⇒ Object 



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# File 'lib/dm-core/associations/many_to_many.rb', line 106

def links
  return @links if defined?(@links)

  @links = []
  links  = [through, via]

  while (relationship = links.shift)
    if relationship.respond_to?(:links)
      links.unshift(*relationship.links)
    else
      @links << relationship
    end
  end

  @links.freeze
end

#query ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future. 



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# File 'lib/dm-core/associations/many_to_many.rb', line 140

def query
  # TODO: consider making this a query_for method, so that ManyToMany::Relationship#query only
  #   returns the query supplied in the definition
  @many_to_many_query ||= super.merge(links: links).freeze
end

#source_scope(source) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future. 



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# File 'lib/dm-core/associations/many_to_many.rb', line 135

def source_scope(source)
  {through.inverse => source}
end

#through ⇒ Object

Intermediate association for through model relationships

Example: for :bugs association in

class Software::Engineer

include DataMapper::Resource

has n, :missing_tests
has n, :bugs, :through => :missing_tests

end

through is :missing_tests

TODO: document a case when

through option is a model and
not an association name



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# File 'lib/dm-core/associations/many_to_many.rb', line 51

def through
  return @through if defined?(@through)

  @through = options[:through]

  return @through if @through.is_a?(Associations::Relationship)

  model           = source_model
  repository_name = source_repository_name
  relationships   = model&.relationships(repository_name)
  name            = through_relationship_name

  @through = relationships[name] ||
             DataMapper.repository(repository_name) do
               model&.has(min..max, name, through_model, one_to_many_options)
             end

  @through.child_key

  @through
end

#via ⇒ Object 



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# File 'lib/dm-core/associations/many_to_many.rb', line 74

def via
  return @via if defined?(@via)

  @via = options[:via]

  return @via if @via.is_a?(Associations::Relationship)

  name            = self.name
  through         = self.through
  repository_name = through.relative_target_repository_name
  through_model   = through.target_model
  relationships   = through_model.relationships(repository_name)
  singular_name   = DataMapper::Inflector.singularize(name.to_s).to_sym

  @via = relationships[@via] ||
         relationships[name] ||
         relationships[singular_name]

  @via ||= if anonymous_through_model?
             DataMapper.repository(repository_name) do
               through_model.belongs_to(singular_name, target_model, many_to_one_options)
             end
           else
             raise UnknownRelationshipError, "No relationships named #{name} or #{singular_name} in #{through_model}"
           end

  @via.child_key

  @via
end