module Pluckers::Features::Base::HasManyThroughReflections
This module implements plucking has_many :through 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. - 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()
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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_through_reflections.rb, line 67 def build_results super return if @has_many_through_reflections.blank? @has_many_through_reflections.each do |name, reflection| # As an example we will imagine that we are plucking Authors and # this relation is the :references, that is a relationship through # BlogPost # We get the meta information about the :through reflection (:references) klass_reflection = @klass_reflections[name] # And also the has_many reflection (:posts) as we wiil need it to fetch information reflection_to_pluck = klass_reflection.chain.reverse.first # initialize some options such as the plucker or the scope of the pluck scope = reflection_to_pluck.klass.send(all_method) # Essentially we are going to pluck the has_many relationship and # add the reflections option so it recursively plucks the has_many # :references reflection from BlogPost. plucker = reflection[:plucker] || Pluckers::Base plucker_options = { attributes: [reflection_to_pluck.foreign_key.to_sym], reflections: { klass_reflection.source_reflection.name => reflection } } # In order to create this intermediary plucker 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( reflection_to_pluck.foreign_key => @results.map{|_, r| r[reflection_to_pluck.active_record_primary_key.to_sym] } ), plucker_options # 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 (BlogPost) we search those records # (Author) that are related (author.id == post.author_id) and # insert not the record itself but the desired reflection in the # result if result[reflection_to_pluck.active_record_primary_key.to_sym] == r[reflection_to_pluck.foreign_key.to_sym] && r[klass_reflection.source_reflection.name] result[name] += [r[klass_reflection.source_reflection.name]].flatten end end end end end
configure_query()
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Here we obtain the has_many :through 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_through_reflections.rb, line 41 def configure_query super pluck_reflections = @options[:reflections] || {} return if pluck_reflections.blank? @has_many_through_reflections = { } # We iterate through the class reflections passed as options @klass_reflections.slice(*pluck_reflections.keys). # And select those that are Through and which delegate reflection is a HasMany select{|_, r| active_record_has_many_through_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_through_reflections[name] = pluck_reflections[name] end end