Class: Rasti::DB::Relations::ManyToMany

Inherits:
Base
  • Object
show all
Defined in:
lib/rasti/db/relations/many_to_many.rb

Instance Attribute Summary

Attributes inherited from Base

#name, #source_collection_class

Instance Method Summary collapse

Methods inherited from Base

#from_many?, #from_one?, #initialize, #join_relation_name, #many_to_many?, #many_to_one?, #one_to_many?, #one_to_one?, #target_collection_class, #to_many?, #to_one?

Constructor Details

This class inherits a constructor from Rasti::DB::Relations::Base

Instance Method Details

#add_join(environment, dataset, prefix = nil) ⇒ Object 



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# File 'lib/rasti/db/relations/many_to_many.rb', line 67

def add_join(environment, dataset, prefix=nil)
  validate_join!

  many_to_many_relation_alias = with_prefix prefix, "#{relation_collection_name}_#{SecureRandom.base64}"

  relation_name = prefix ? Sequel[prefix] : Sequel[source_collection_class.collection_name]

  many_to_many_condition = {
    Sequel[many_to_many_relation_alias][source_foreign_key] => relation_name[source_collection_class.primary_key]
  }

  relation_alias = join_relation_name prefix

  relation_condition = {
    Sequel[relation_alias][target_collection_class.primary_key] => Sequel[many_to_many_relation_alias][target_foreign_key]
  }

  dataset.join(qualified_relation_collection_name(environment).as(many_to_many_relation_alias), many_to_many_condition)
         .join(environment.qualify_collection(target_collection_class).as(relation_alias), relation_condition)
end

#apply_filter(environment, dataset, primary_keys) ⇒ Object 



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# File 'lib/rasti/db/relations/many_to_many.rb', line 88

def apply_filter(environment, dataset, primary_keys)
  if source_collection_class.data_source_name == relation_data_source_name
    dataset.join(qualified_relation_collection_name(environment), source_foreign_key => source_collection_class.primary_key)
           .where(Sequel[relation_collection_name][target_foreign_key] => primary_keys)
           .select_all(source_collection_class.collection_name)
           .distinct
  else
    data_source = environment.data_source relation_data_source_name
    fks = data_source.db.from(data_source.qualify(relation_collection_name))
                        .where(target_collection_class.foreign_key => primary_keys)
                        .select_map(source_collection_class.foreign_key)
                        .uniq
    dataset.where(source_collection_class.primary_key => fks)
  end
end

#fetch_graph(environment, rows, selected_attributes = nil, excluded_attributes = nil, relations_graph = nil) ⇒ Object 



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# File 'lib/rasti/db/relations/many_to_many.rb', line 22

def fetch_graph(environment, rows, selected_attributes=nil, excluded_attributes=nil, relations_graph=nil)
  pks = rows.map { |row| row[source_collection_class.primary_key] }

  if target_collection_class.data_source_name == relation_data_source_name
    target_data_source = environment.data_source_of target_collection_class

    dataset = target_data_source.db.from(environment.qualify_collection(target_collection_class))
                                   .join(qualified_relation_collection_name(environment), target_foreign_key => target_collection_class.primary_key)
                                   .where(Sequel[relation_collection_name][source_foreign_key] => pks)
                                   .select_all(target_collection_class.collection_name)

    selected_attributes ||= target_collection_class.collection_attributes - excluded_attributes if excluded_attributes
    dataset = dataset.select(*selected_attributes.map { |a| Sequel[target_collection_class.collection_name][a] }) if selected_attributes

    join_rows = dataset.select_append(Sequel[relation_collection_name][source_foreign_key].as(:source_foreign_key)).all
  else
    relation_data_source = environment.data_source relation_data_source_name

    relation_index = relation_data_source.db.from(relation_data_source.qualify(relation_collection_name))
                                            .where(source_foreign_key => pks)
                                            .select_hash_groups(target_foreign_key, source_foreign_key)

    query = target_collection_class.new environment
    query = query.exclude_attributes(*excluded_attributes) if excluded_attributes
    query = query.select_attributes(*selected_attributes) if selected_attributes

    join_rows = query.where(target_collection_class.primary_key => relation_index.keys).raw.flat_map do |row|
      relation_index[row[target_collection_class.primary_key]].map do |source_primary_key|
        row.merge(source_foreign_key: source_primary_key)
      end
    end
  end

  relations_graph.fetch_graph join_rows if relations_graph

  relation_rows = join_rows.each_with_object(Hash.new { |h,k| h[k] = [] }) do |row, hash|
    attributes = row.select { |attr,_| target_collection_class.model.attribute_names.include? attr }
    hash[row[:source_foreign_key]] << target_collection_class.model.new(attributes)
  end

  rows.each do |row|
    row[name] = relation_rows.fetch row[source_collection_class.primary_key], []
  end
end

#relation_collection_name ⇒ Object 



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# File 'lib/rasti/db/relations/many_to_many.rb', line 14

def relation_collection_name
  @relation_collection_name ||= options[:relation_collection_name] || [source_collection_class.collection_name, target_collection_class.collection_name].sort.join('_').to_sym
end

#relation_data_source_name ⇒ Object 



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# File 'lib/rasti/db/relations/many_to_many.rb', line 18

def relation_data_source_name
  @relation_data_source_name ||= options[:relation_data_source_name] || source_collection_class.data_source_name
end

#source_foreign_key ⇒ Object 



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# File 'lib/rasti/db/relations/many_to_many.rb', line 6

def source_foreign_key
  @source_foreign_key ||= options[:source_foreign_key] || source_collection_class.foreign_key
end

#target_foreign_key ⇒ Object 



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# File 'lib/rasti/db/relations/many_to_many.rb', line 10

def target_foreign_key
  @target_foreign_key ||= options[:target_foreign_key] || target_collection_class.foreign_key
end