module Pluckers::Features::Base::HasManyReflections

This module implements plucking has_many relationships in a recursive way.

The options used in this feature are:

* reflections: A hash of the reflections we will pluck recursively. The
  key of this hash will be the name of the reflection and the value is
  another hash of options.

  - scope: You can limit the scope of the objects plucked. E.g, you
    could use Author.active instead of Author.all. Notice that .all is
    the default.

  - plucker: You can use a custom plucker instead of Pluckers::Base in
    case you want any specific logic. Pluckers::Base is the default one.

  - only_ids: We can get the _ids array instead of an array with hashes
    if we pass this option as true. If we do any fields or plucker
    option will be ignored.

  - Any other option will be passed to the plucker, so you can send any
    other regular option such as attributes, custom ones or even more
    reflections. Recursivity FTW!!

Public Instance Methods

build_results() click to toggle source

In this method we get the reflections and for each one creates and executes a new plucker.

This pluck gives the whole process a recursive character and options for that plucker may be passed in the options hash.

Calls superclass method
# File lib/pluckers/features/base/has_many_reflections.rb, line 72
def build_results
  super

  return if @has_many_reflections.blank?

  build_complete_reflections
  build_only_ids_reflections

end
configure_query() click to toggle source

Here we obtain the has_many reflections to include in the pluck operation and also include the relation foreign key in the attributes to pluck for this model.

Calls superclass method
# File lib/pluckers/features/base/has_many_reflections.rb, line 45
def configure_query
  super

  pluck_reflections = @options[:reflections] || {}

  return if pluck_reflections.blank?

  @has_many_reflections = { }

  # We iterate through the class reflections passed as options
  @klass_reflections.slice(*pluck_reflections.keys).
  # And select those that are HasMany
    select{|_, r| active_record_has_many_reflection?(r)}.
  # And store them in the has_many_reflection hash that will be used later
    each do |name, reflection|
      name = name.to_sym
      @has_many_reflections[name] = pluck_reflections[name]
    end

end

Private Instance Methods

build_complete_reflections() click to toggle source

This method build the reflections completely, creating hashes for each record, etc.

It searches reflections that has not the :only_ids option enabled and then creates pluckers for them.

# File lib/pluckers/features/base/has_many_reflections.rb, line 87
        def build_complete_reflections

  @has_many_reflections.reject {|_, reflection| reflection[:only_ids] }.each do |name, reflection|
    # As an example we will imagine that we are plucking Authors and
    # this relation is the :posts

    # We get the meta information about the reflection
    klass_reflection = @klass_reflections[name]


    # initialize some options such as the plucker or the scope of the pluck
    scope = reflection[:scope] || klass_reflection.klass.send(all_method)
    plucker = reflection[:plucker] || Pluckers::Base

    # If there are attributes configured to be plucked we add the foreign
    # key as we will need it to relate the records
    reflection[:attributes] |= [klass_reflection.foreign_key.to_sym] if reflection[:attributes]

    # If the has_many is an :as relationship (inverse of a polymorphic
    # one) we should filter the ones with the right class
    if klass_reflection.options[:as]
      scope = scope.where(klass_reflection.type => klass_reflection.active_record.class_name)
    end

    # And now we create the plucker. Notice that we add a where to the
    # scope, so we filter the records to pluck as we only get those with
    # an id in the set of the foreign keys of the records already
    # plucked by the base plucker
    #
    # In our Example we would be doing something like
    # BlogPost.all.where(author_id: author_ids)
    reflection_plucker = plucker.new scope.where(
        klass_reflection.foreign_key => @results.map{|_, r| r[klass_reflection.active_record_primary_key.to_sym] }
      ),
      reflection

    # We initialize so we return an empty array if there are no record
    # related
    @results.each do |_, result|
      result[name] ||= []
    end

    reflection_plucker.pluck.each do |r|
      @results.each do |_,result|
        # For each related result (Author) we search those records
        # (BlogPost) that are related (author.id == post.author_id) and
        # insert them in the relationship attributes
        if result[klass_reflection.active_record_primary_key.to_sym] == r[klass_reflection.foreign_key.to_sym]
          result[name] << r
        end
      end
    end

  end
end
build_only_ids_reflections() click to toggle source

This method build the ids for the records instead of creating the hashes.

It searches reflections that has the :only_ids option enabled and then creates pluckers for them.

# File lib/pluckers/features/base/has_many_reflections.rb, line 148
        def build_only_ids_reflections

  @has_many_reflections.select {|_, reflection| reflection[:only_ids] }.each do |name, reflection|
    # As an example we will imagine that we are plucking Authors and
    # this relation is the :posts

    # We get the meta information about the reflection
    klass_reflection = @klass_reflections[name]

    # We can send an scope option for filtering the related records
    scope = reflection[:scope] || klass_reflection.klass.send(all_method)

    # We override the attributes as we only get the required ones for
    # relating the records
    reflection[:attributes] = [klass_reflection.foreign_key.to_sym, klass_reflection.active_record_primary_key.to_sym]

    # And now, create the plucker, filtering the records so we only get
    # the related ones
    reflection_plucker = Pluckers::Base.new scope.where(
        klass_reflection.foreign_key => @results.map{|_, r| r[klass_reflection.active_record_primary_key.to_sym] }
      ),
      reflection

    # Now we create the _ids attribute for each result
    ids_reflection_name = "#{name.to_s.singularize}_ids".to_sym

    @results.each do |_, result|
      result[ids_reflection_name] ||= []
    end


    reflection_plucker.pluck.each do |r|
      @results.
        each do |_,result|
          # For each related result (Author) we search those records
          # (BlogPost) that are related (author.id == post.author_id) and
          # insert the id in the _ids array
          if result[klass_reflection.active_record_primary_key.to_sym] == r[klass_reflection.foreign_key.to_sym]
            result[ids_reflection_name] << r[klass_reflection.active_record_primary_key.to_sym]
          end
        end
    end

  end

end