Module: CompositePrimaryKeys::ActiveRecord::AssociationPreload::ClassMethods

Defined in:
lib/composite_primary_keys/association_preload.rb

Overview

Composite key versions of Association functions

Instance Method Summary collapse

Instance Method Details

#construct_id_map_for_composite(records) ⇒ Object

Given a collection of ActiveRecord objects, constructs a Hash which maps the objects’ IDs to the relevant objects. Returns a 2-tuple (id_to_record_map, ids) where id_to_record_map is the Hash, and ids is an Array of record IDs.



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# File 'lib/composite_primary_keys/association_preload.rb', line 226

def construct_id_map_for_composite(records)
  id_to_record_map = {}
  ids = []
  records.each do |record|
    primary_key ||= record.class.primary_key
    ids << record.id
    mapped_records = (id_to_record_map[record.id.to_s] ||= [])
    mapped_records << record
  end
  ids.uniq!
  return id_to_record_map, ids
end

#find_associated_records(ids, reflection, preload_options) ⇒ Object 



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# File 'lib/composite_primary_keys/association_preload.rb', line 189

def find_associated_records(ids, reflection, preload_options)
  options = reflection.options
  table_name = reflection.klass.quoted_table_name

  if interface = reflection.options[:as]
    raise AssociationNotSupported, "Polymorphic joins not supported for composite keys"
  else
    connection = reflection.active_record.connection
    foreign_key = reflection.primary_key_name
    conditions = ["#{table_name}.#{connection.quote_column_name(foreign_key)} IN (?)", ids]
    
    if composite?
      foreign_keys = foreign_key.to_s.split(CompositePrimaryKeys::ID_SEP)
    
      where = (foreign_keys * ids.size).in_groups_of(foreign_keys.size).map do |keys|
        "(" + keys.map{|key| "#{table_name}.#{connection.quote_column_name(key)} = ?"}.join(" AND ") + ")"
      end.join(" OR ")

      conditions = [where, ids].flatten
    end
  end

  conditions.first << append_conditions(reflection, preload_options)

  reflection.klass.find(:all,
    :select     => (preload_options[:select] || options[:select] || "#{table_name}.*"),
    :include    => preload_options[:include] || options[:include],
    :conditions => conditions,
    :joins      => options[:joins],
    :group      => preload_options[:group] || options[:group],
    :order      => preload_options[:order] || options[:order])
end

#full_composite_join_clause(reflection, table1, full_keys1, table2, full_keys2) ⇒ Object 



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# File 'lib/composite_primary_keys/association_preload.rb', line 239

def full_composite_join_clause(reflection, table1, full_keys1, table2, full_keys2)
  connection = reflection.active_record.connection
  full_keys1 = full_keys1.split(CompositePrimaryKeys::ID_SEP) if full_keys1.is_a?(String)
  full_keys2 = full_keys2.split(CompositePrimaryKeys::ID_SEP) if full_keys2.is_a?(String)
  where_clause = [full_keys1, full_keys2].transpose.map do |key_pair|
    quoted1 = connection.quote_table_name(table1)
    quoted2 = connection.quote_table_name(table2)
    "#{quoted1}.#{connection.quote_column_name(key_pair.first)}=#{quoted2}.#{connection.quote_column_name(key_pair.last)}"
  end.join(" AND ")
  "(#{where_clause})"
end

#preload_belongs_to_association(records, reflection, preload_options = {}) ⇒ Object 



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# File 'lib/composite_primary_keys/association_preload.rb', line 103

def preload_belongs_to_association(records, reflection, preload_options={})
  options = reflection.options
  primary_key_name = reflection.primary_key_name.to_s.split(CompositePrimaryKeys::ID_SEP)

  if options[:polymorphic]
    raise AssociationNotSupported, "Polymorphic joins not supported for composite keys"
  else
    # I need to keep the original ids for each record (as opposed to the stringified) so
    # that they get properly converted for each db so the id_map ends up looking like:
    #
    # { '1,2' => {:id => [1,2], :records => [...records...]}}
    id_map = {}

    records.each do |record|
      key = primary_key_name.map{|k| record.send(k)}
      key_as_string = key.join(CompositePrimaryKeys::ID_SEP)

      if key_as_string
        mapped_records = (id_map[key_as_string] ||= {:id => key, :records => []})
        mapped_records[:records] << record
      end
    end


    klasses_and_ids = [[reflection.klass.name, id_map]]
  end

  klasses_and_ids.each do |klass_and_id|
    klass_name, id_map = *klass_and_id
    klass = klass_name.constantize
    table_name = klass.quoted_table_name
    connection = reflection.active_record.connection

    if composite?
      primary_key = klass.primary_key.to_s.split(CompositePrimaryKeys::ID_SEP)
      ids = id_map.keys.uniq.map {|id| id_map[id][:id]}

      where = (primary_key * ids.size).in_groups_of(primary_key.size).map do |keys|
         "(" + keys.map{|key| "#{table_name}.#{connection.quote_column_name(key)} = ?"}.join(" AND ") + ")"
      end.join(" OR ")

      conditions = [where, ids].flatten
    else
      conditions = ["#{table_name}.#{connection.quote_column_name(primary_key)} IN (?)", id_map.keys.uniq]
    end

    conditions.first << append_conditions(reflection, preload_options)

    associated_records = klass.find(:all,
      :conditions => conditions,
      :include    => options[:include],
      :select     => options[:select],
      :joins      => options[:joins],
      :order      => options[:order])

    set_association_single_records(id_map, reflection.name, associated_records, primary_key)
  end
end

#preload_has_and_belongs_to_many_association(records, reflection, preload_options = {}) ⇒ Object 



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# File 'lib/composite_primary_keys/association_preload.rb', line 11

def preload_has_and_belongs_to_many_association(records, reflection, preload_options={})
  table_name = reflection.klass.quoted_table_name
  id_to_record_map, ids = construct_id_map_for_composite(records)
  records.each {|record| record.send(reflection.name).loaded}
  options = reflection.options

  if composite?
    primary_key = reflection.primary_key_name.to_s.split(CompositePrimaryKeys::ID_SEP)
    where = (primary_key * ids.size).in_groups_of(primary_key.size).map do |keys|
      "(" + keys.map{|key| "t0.#{connection.quote_column_name(key)} = ?"}.join(" AND ") + ")"
    end.join(" OR ")

    conditions = [where, ids].flatten
    joins = "INNER JOIN #{connection.quote_table_name options[:join_table]} t0 ON #{full_composite_join_clause(reflection, reflection.klass.table_name, reflection.klass.primary_key, 't0', reflection.association_foreign_key)}"
    parent_primary_keys = reflection.primary_key_name.to_s.split(CompositePrimaryKeys::ID_SEP).map{|k| "t0.#{connection.quote_column_name(k)}"}
    parent_record_id = connection.concat(*parent_primary_keys.zip(["','"] * (parent_primary_keys.size - 1)).flatten.compact)
  else
    conditions = ["t0.#{connection.quote_column_name(reflection.primary_key_name)}  IN (?)", ids]
    joins = "INNER JOIN #{connection.quote_table_name options[:join_table]} t0 ON #{reflection.klass.quoted_table_name}.#{connection.quote_column_name(reflection.klass.primary_key)} = t0.#{connection.quote_column_name(reflection.association_foreign_key)})"
    parent_record_id = reflection.primary_key_name
  end

  conditions.first << append_conditions(reflection, preload_options)

  associated_records = reflection.klass.find(:all,
    :conditions => conditions,
    :include    => options[:include],
    :joins      => joins,
    :select     => "#{options[:select] || table_name+'.*'}, #{parent_record_id} as parent_record_id_",
    :order      => options[:order])

  set_association_collection_records(id_to_record_map, reflection.name, associated_records, 'parent_record_id_')
end

#preload_has_many_association(records, reflection, preload_options = {}) ⇒ Object 



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# File 'lib/composite_primary_keys/association_preload.rb', line 45

def preload_has_many_association(records, reflection, preload_options={})
  id_to_record_map, ids = construct_id_map_for_composite(records)
  records.each {|record| record.send(reflection.name).loaded}
  options = reflection.options

  if options[:through]
    through_records = preload_through_records(records, reflection, options[:through])
    through_reflection = reflections[options[:through]]
    through_primary_key = through_reflection.primary_key_name

    unless through_records.empty?
      source = reflection.source_reflection.name
      #add conditions from reflection!
      through_records.first.class.preload_associations(through_records, source, reflection.options)
      through_records.each do |through_record|
        key = through_primary_key.to_s.split(CompositePrimaryKeys::ID_SEP).map{|k| through_record.send(k)}.join(CompositePrimaryKeys::ID_SEP)
        add_preloaded_records_to_collection(id_to_record_map[key], reflection.name, through_record.send(source))
      end
    end
  else
    associated_records = find_associated_records(ids, reflection, preload_options)
    set_association_collection_records(id_to_record_map, reflection.name, associated_records, reflection.primary_key_name.to_s.split(CompositePrimaryKeys::ID_SEP))
  end
end

#preload_through_records(records, reflection, through_association) ⇒ Object 



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# File 'lib/composite_primary_keys/association_preload.rb', line 70

def preload_through_records(records, reflection, through_association)
  through_reflection = reflections[through_association]
  through_primary_key = through_reflection.primary_key_name

  if reflection.options[:source_type]
    interface = reflection.source_reflection.options[:foreign_type]
    preload_options = {:conditions => ["#{connection.quote_column_name interface} = ?", reflection.options[:source_type]]}

    records.compact!
    records.first.class.preload_associations(records, through_association, preload_options)

    # Dont cache the association - we would only be caching a subset
    through_records = []
    records.each do |record|
      proxy = record.send(through_association)

      if proxy.respond_to?(:target)
        through_records << proxy.target
        proxy.reset
      else # this is a has_one :through reflection
        through_records << proxy if proxy
      end
    end
    through_records.flatten!
  else
    records.first.class.preload_associations(records, through_association)
    through_records = records.map {|record| record.send(through_association)}.flatten
  end

  through_records.compact!
  through_records
end

#set_association_collection_records(id_to_record_map, reflection_name, associated_records, key) ⇒ Object 



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# File 'lib/composite_primary_keys/association_preload.rb', line 162

def set_association_collection_records(id_to_record_map, reflection_name, associated_records, key)
  associated_records.each do |associated_record|
    associated_record_key = associated_record[key]
    associated_record_key = associated_record_key.is_a?(Array) ? associated_record_key.join(CompositePrimaryKeys::ID_SEP) : associated_record_key.to_s
    mapped_records = id_to_record_map[associated_record_key]
    add_preloaded_records_to_collection(mapped_records, reflection_name, associated_record)
  end
end

#set_association_single_records(id_to_record_map, reflection_name, associated_records, key) ⇒ Object 



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# File 'lib/composite_primary_keys/association_preload.rb', line 171

def set_association_single_records(id_to_record_map, reflection_name, associated_records, key)
  seen_keys = {}
  associated_records.each do |associated_record|
    associated_record_key = associated_record[key]
    associated_record_key = associated_record_key.is_a?(Array) ? associated_record_key.join(CompositePrimaryKeys::ID_SEP) : associated_record_key.to_s

    #this is a has_one or belongs_to: there should only be one record.
    #Unfortunately we can't (in portable way) ask the database for 'all records where foo_id in (x,y,z), but please
    # only one row per distinct foo_id' so this where we enforce that
    next if seen_keys[associated_record_key]
    seen_keys[associated_record_key] = true
    mapped_records = id_to_record_map[associated_record_key][:records]
    mapped_records.each do |mapped_record|
      mapped_record.send("set_#{reflection_name}_target", associated_record)
    end
  end
end