module ArelHelpers::JoinAssociation

Public Class Methods

join_association(table, association, join_type = Arel::Nodes::InnerJoin, options = {}, &block) click to toggle source

activerecord uses JoinDependency to automagically generate inner join statements for any type of association (belongs_to, has_many, and has_and_belongs_to_many). For example, for HABTM associations, two join statements are required. This method encapsulates that functionality and yields an intermediate object for chaining. It also allows you to use an outer join instead of the default inner via the join_type arg.

# File lib/arel-helpers/join_association.rb, line 19
def join_association(table, association, join_type = Arel::Nodes::InnerJoin, options = {}, &block)
  if ActiveRecord::VERSION::STRING >= '5.2.0'
    join_association_5_2(table, association, join_type, options, &block)
  elsif ActiveRecord::VERSION::STRING >= '5.0.0'
    join_association_5_0(table, association, join_type, options, &block)
  elsif ActiveRecord::VERSION::STRING >= '4.2.0'
    join_association_4_2(table, association, join_type, options, &block)
  elsif ActiveRecord::VERSION::STRING >= '4.1.0'
    join_association_4_1(table, association, join_type, options, &block)
  else
    join_association_3_1(table, association, join_type, options, &block)
  end
end

Private Class Methods

find_alias(name, aliases) click to toggle source
# File lib/arel-helpers/join_association.rb, line 192
def find_alias(name, aliases)
  aliases.find { |a| a.table_name == name }
end
join_association_3_1(table, association, join_type, options = {}) { |left.to_sym, right| ... } click to toggle source
# File lib/arel-helpers/join_association.rb, line 35
def join_association_3_1(table, association, join_type, options = {})
  aliases = options.fetch(:aliases, {})
  associations = association.is_a?(Array) ? association : [association]
  join_dependency = ActiveRecord::Associations::JoinDependency.new(table, associations, [])
  manager = Arel::SelectManager.new(table)

  join_dependency.join_associations.each do |assoc|
    assoc.join_type = join_type
    assoc.join_to(manager)
  end

  manager.join_sources.map do |assoc|
    if found_alias = find_alias(assoc.left.name, aliases)
      assoc.left.table_alias = found_alias.name
    end

    if block_given?
      # yield |assoc_name, join_conditions|
      right = yield assoc.left.name.to_sym, assoc.right
      assoc.class.new(assoc.left, right)
    else
      assoc
    end
  end
end
join_association_4_1(table, association, join_type, options = {}) { |left.to_sym, right| ... } click to toggle source
# File lib/arel-helpers/join_association.rb, line 61
def join_association_4_1(table, association, join_type, options = {})
  aliases = options.fetch(:aliases, {})
  associations = association.is_a?(Array) ? association : [association]
  join_dependency = ActiveRecord::Associations::JoinDependency.new(table, associations, [])

  join_dependency.join_constraints([]).map do |constraint|
    right = if block_given?
      yield constraint.left.name.to_sym, constraint.right
    else
      constraint.right
    end

    if found_alias = find_alias(constraint.left.name, aliases)
      constraint.left.table_alias = found_alias.name
    end

    join_type.new(constraint.left, right)
  end
end
join_association_4_2(table, association, join_type, options = {}) { |left.to_sym, right| ... } click to toggle source

ActiveRecord 4.2 moves bind variables out of the join classes and into the relation. For this reason, a method like ::join_association isn't able to add to the list of bind variables dynamically. To get around the problem, this method must return a string.

# File lib/arel-helpers/join_association.rb, line 86
def join_association_4_2(table, association, join_type, options = {})
  aliases = options.fetch(:aliases, [])
  associations = association.is_a?(Array) ? association : [association]
  join_dependency = ActiveRecord::Associations::JoinDependency.new(table, associations, [])

  constraints = join_dependency.join_constraints([])

  binds = constraints.flat_map do |info|
    info.binds.map { |bv| table.connection.quote(*bv.reverse) }
  end

  joins = constraints.flat_map do |constraint|
    constraint.joins.map do |join|
      right = if block_given?
        yield join.left.name.to_sym, join.right
      else
        join.right
      end

      if found_alias = find_alias(join.left.name, aliases)
        join.left.table_alias = found_alias.name
      end

      join_type.new(join.left, right)
    end
  end

  join_strings = joins.map do |join|
    to_sql(join, table, binds)
  end

  join_strings.join(' ')
end
join_association_5_0(table, association, join_type, options = {}) { |left.to_sym, right| ... } click to toggle source
# File lib/arel-helpers/join_association.rb, line 120
def join_association_5_0(table, association, join_type, options = {})
  aliases = options.fetch(:aliases, [])
  associations = association.is_a?(Array) ? association : [association]
  join_dependency = ActiveRecord::Associations::JoinDependency.new(table, associations, [])

  constraints = join_dependency.join_constraints([], join_type)

  binds = constraints.flat_map do |info|
    prepared_binds = info.binds.map(&:value_for_database)
    prepared_binds.map { |value| table.connection.quote(value) }
  end

  joins = constraints.flat_map do |constraint|
    constraint.joins.map do |join|
      right = if block_given?
        yield join.left.name.to_sym, join.right
      else
        join.right
      end

      if found_alias = find_alias(join.left.name, aliases)
        join.left.table_alias = found_alias.name
      end

      join_type.new(join.left, right)
    end
  end

  join_strings = joins.map do |join|
    to_sql(join, table, binds)
  end

  join_strings.join(' ')
end
join_association_5_2(table, association, join_type, options = {}) { |left.to_sym, right| ... } click to toggle source
# File lib/arel-helpers/join_association.rb, line 155
def join_association_5_2(table, association, join_type, options = {})
  aliases = options.fetch(:aliases, [])
  associations = association.is_a?(Array) ? association : [association]

  alias_tracker = ActiveRecord::Associations::AliasTracker.create(
    table.connection, table.name, {}
  )

  join_dependency = ActiveRecord::Associations::JoinDependency.new(
    table, table.arel_table, associations, alias_tracker
  )

  constraints = join_dependency.join_constraints([], join_type)

  constraints.map do |join|
    right = if block_given?
      yield join.left.name.to_sym, join.right
    else
      join.right
    end

    if found_alias = find_alias(join.left.name, aliases)
      join.left.table_alias = found_alias.name
    end

    join_type.new(join.left, right)
  end
end
to_sql(node, table, binds) click to toggle source
# File lib/arel-helpers/join_association.rb, line 186
def to_sql(node, table, binds)
  visitor = table.connection.visitor
  collect = visitor.accept(node, Arel::Collectors::Bind.new)
  collect.substitute_binds(binds).join
end