diff options
Diffstat (limited to 'activerecord/lib/active_record/associations/alias_tracker.rb')
-rw-r--r-- | activerecord/lib/active_record/associations/alias_tracker.rb | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/associations/alias_tracker.rb b/activerecord/lib/active_record/associations/alias_tracker.rb new file mode 100644 index 0000000000..6fc2bfdb31 --- /dev/null +++ b/activerecord/lib/active_record/associations/alias_tracker.rb @@ -0,0 +1,85 @@ +require 'active_support/core_ext/string/conversions' + +module ActiveRecord + module Associations + # Keeps track of table aliases for ActiveRecord::Associations::ClassMethods::JoinDependency and + # ActiveRecord::Associations::ThroughAssociationScope + class AliasTracker # :nodoc: + attr_reader :aliases, :table_joins + + # table_joins is an array of arel joins which might conflict with the aliases we assign here + def initialize(table_joins = []) + @aliases = Hash.new + @table_joins = table_joins + end + + def aliased_table_for(table_name, aliased_name = nil) + table_alias = aliased_name_for(table_name, aliased_name) + + if table_alias == table_name # TODO: Is this conditional necessary? + Arel::Table.new(table_name) + else + Arel::Table.new(table_name).alias(table_alias) + end + end + + def aliased_name_for(table_name, aliased_name = nil) + aliased_name ||= table_name + + initialize_count_for(table_name) if aliases[table_name].nil? + + if aliases[table_name].zero? + # If it's zero, we can have our table_name + aliases[table_name] = 1 + table_name + else + # Otherwise, we need to use an alias + aliased_name = connection.table_alias_for(aliased_name) + + initialize_count_for(aliased_name) if aliases[aliased_name].nil? + + # Update the count + aliases[aliased_name] += 1 + + if aliases[aliased_name] > 1 + "#{truncate(aliased_name)}_#{aliases[aliased_name]}" + else + aliased_name + end + end + end + + def pluralize(table_name) + ActiveRecord::Base.pluralize_table_names ? table_name.to_s.pluralize : table_name + end + + private + + def initialize_count_for(name) + aliases[name] = 0 + + unless Arel::Table === 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 + + aliases[name] += table_joins.map { |join| + # Table names + table aliases + join.left.downcase.scan( + /join(?:\s+\w+)?\s+(\S+\s+)?#{quoted_name}\son/ + ).size + }.sum + end + + aliases[name] + end + + def truncate(name) + name[0..connection.table_alias_length-3] + end + + def connection + ActiveRecord::Base.connection + end + end + end +end |