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require "active_support/core_ext/string/conversions"
module ActiveRecord
module Associations
# Keeps track of table aliases for ActiveRecord::Associations::JoinDependency
class AliasTracker # :nodoc:
def self.create(connection, initial_table)
aliases = Hash.new(0)
aliases[initial_table] = 1
new(connection, aliases)
end
def self.create_with_joins(connection, initial_table, joins)
if joins.empty?
create(connection, initial_table)
else
aliases = Hash.new { |h, k|
h[k] = initial_count_for(connection, k, joins)
}
aliases[initial_table] = 1
new(connection, aliases)
end
end
def self.initial_count_for(connection, name, table_joins)
# quoted_name should be downcased as some database adapters (Oracle) return quoted name in uppercase
quoted_name = connection.quote_table_name(name).downcase
counts = table_joins.map do |join|
if join.is_a?(Arel::Nodes::StringJoin)
# Table names + table aliases
join.left.downcase.scan(
/join(?:\s+\w+)?\s+(\S+\s+)?#{quoted_name}\son/
).size
elsif join.respond_to? :left
join.left.table_name == name ? 1 : 0
else
# this branch is reached by two tests:
#
# activerecord/test/cases/associations/cascaded_eager_loading_test.rb:37
# with :posts
#
# activerecord/test/cases/associations/eager_test.rb:1133
# with :comments
#
0
end
end
counts.sum
end
# table_joins is an array of arel joins which might conflict with the aliases we assign here
def initialize(connection, aliases)
@aliases = aliases
@connection = connection
end
def aliased_table_for(table_name, aliased_name, type_caster)
if aliases[table_name].zero?
# If it's zero, we can have our table_name
aliases[table_name] = 1
Arel::Table.new(table_name, type_caster: type_caster)
else
# Otherwise, we need to use an alias
aliased_name = @connection.table_alias_for(aliased_name)
# Update the count
aliases[aliased_name] += 1
table_alias = if aliases[aliased_name] > 1
"#{truncate(aliased_name)}_#{aliases[aliased_name]}"
else
aliased_name
end
Arel::Table.new(table_name, type_caster: type_caster).alias(table_alias)
end
end
# TODO Change this to private once we've dropped Ruby 2.2 support.
# Workaround for Ruby 2.2 "private attribute?" warning.
protected
attr_reader :aliases
private
def truncate(name)
name.slice(0, @connection.table_alias_length - 2)
end
end
end
end
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