Organize Relation methods into separate modules

3 files changed, 429 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/relation/calculation_methods.rb b/activerecord/lib/active_record/relation/calculation_methods.rb
new file mode 100644
index 0000000000..a925a99464
--- /dev/null
+++ b/activerecord/lib/active_record/relation/calculation_methods.rb
@@ -0,0 +1,177 @@
+module ActiveRecord
+  module CalculationMethods
+
+    def count(*args)
+      calculate(:count, *construct_count_options_from_args(*args))
+    end
+
+    def average(column_name)
+      calculate(:average, column_name)
+    end
+
+    def minimum(column_name)
+      calculate(:minimum, column_name)
+    end
+
+    def maximum(column_name)
+      calculate(:maximum, column_name)
+    end
+
+    def sum(column_name)
+      calculate(:sum, column_name)
+    end
+
+    def calculate(operation, column_name, options = {})
+      operation = operation.to_s.downcase
+
+      if operation == "count"
+        joins = @relation.joins(relation)
+        if joins.present? && joins =~ /LEFT OUTER/i
+          distinct = true
+          column_name = @klass.primary_key if column_name == :all
+        end
+
+        distinct = nil if column_name.to_s =~ /\s*DISTINCT\s+/i
+        distinct ||= options[:distinct]
+      else
+        distinct = nil
+      end
+
+      distinct = options[:distinct] || distinct
+      column_name = :all if column_name.blank? && operation == "count"
+
+      if @relation.send(:groupings).any?
+        return execute_grouped_calculation(operation, column_name)
+      else
+        return execute_simple_calculation(operation, column_name, distinct)
+      end
+    rescue ThrowResult
+      0
+    end
+
+    private
+
+    def execute_simple_calculation(operation, column_name, distinct) #:nodoc:
+      column = if @klass.column_names.include?(column_name.to_s)
+        Arel::Attribute.new(@klass.arel_table, column_name)
+      else
+        Arel::SqlLiteral.new(column_name == :all ? "*" : column_name.to_s)
+      end
+
+      relation = select(operation == 'count' ? column.count(distinct) : column.send(operation))
+      type_cast_calculated_value(@klass.connection.select_value(relation.to_sql), column_for(column_name), operation)
+    end
+
+    def execute_grouped_calculation(operation, column_name) #:nodoc:
+      group_attr      = @relation.send(:groupings).first.value
+      association     = @klass.reflect_on_association(group_attr.to_sym)
+      associated      = association && association.macro == :belongs_to # only count belongs_to associations
+      group_field     = associated ? association.primary_key_name : group_attr
+      group_alias     = column_alias_for(group_field)
+      group_column    = column_for(group_field)
+
+      group = @klass.connection.adapter_name == 'FrontBase' ? group_alias : group_field
+
+      aggregate_alias = column_alias_for(operation, column_name)
+
+      select_statement = if operation == 'count' && column_name == :all
+        "COUNT(*) AS count_all"
+      else
+        Arel::Attribute.new(@klass.arel_table, column_name).send(operation).as(aggregate_alias).to_sql
+      end
+
+      select_statement <<  ", #{group_field} AS #{group_alias}"
+
+      relation = select(select_statement).group(group)
+
+      calculated_data = @klass.connection.select_all(relation.to_sql)
+
+      if association
+        key_ids     = calculated_data.collect { |row| row[group_alias] }
+        key_records = association.klass.base_class.find(key_ids)
+        key_records = key_records.inject({}) { |hsh, r| hsh.merge(r.id => r) }
+      end
+
+      calculated_data.inject(ActiveSupport::OrderedHash.new) do |all, row|
+        key   = type_cast_calculated_value(row[group_alias], group_column)
+        key   = key_records[key] if associated
+        value = row[aggregate_alias]
+        all[key] = type_cast_calculated_value(value, column_for(column_name), operation)
+        all
+      end
+    end
+
+    def construct_count_options_from_args(*args)
+      options     = {}
+      column_name = :all
+
+      # Handles count(), count(:column), count(:distinct => true), count(:column, :distinct => true)
+      # TODO : relation.projections only works when .select() was last in the chain. Fix it!
+      case args.size
+      when 0
+        select = get_projection_name_from_chained_relations
+        column_name = select if select !~ /(,|\*)/
+      when 1
+        if args[0].is_a?(Hash)
+          select = get_projection_name_from_chained_relations
+          column_name = select if select !~ /(,|\*)/
+          options = args[0]
+        else
+          column_name = args[0]
+        end
+      when 2
+        column_name, options = args
+      else
+        raise ArgumentError, "Unexpected parameters passed to count(): #{args.inspect}"
+      end
+
+      [column_name || :all, options]
+    end
+
+    # Converts the given keys to the value that the database adapter returns as
+    # a usable column name:
+    #
+    #   column_alias_for("users.id")                 # => "users_id"
+    #   column_alias_for("sum(id)")                  # => "sum_id"
+    #   column_alias_for("count(distinct users.id)") # => "count_distinct_users_id"
+    #   column_alias_for("count(*)")                 # => "count_all"
+    #   column_alias_for("count", "id")              # => "count_id"
+    def column_alias_for(*keys)
+      table_name = keys.join(' ')
+      table_name.downcase!
+      table_name.gsub!(/\*/, 'all')
+      table_name.gsub!(/\W+/, ' ')
+      table_name.strip!
+      table_name.gsub!(/ +/, '_')
+
+      @klass.connection.table_alias_for(table_name)
+    end
+
+    def column_for(field)
+      field_name = field.to_s.split('.').last
+      @klass.columns.detect { |c| c.name.to_s == field_name }
+    end
+
+    def type_cast_calculated_value(value, column, operation = nil)
+      case operation
+        when 'count' then value.to_i
+        when 'sum'   then type_cast_using_column(value || '0', column)
+        when 'average'   then value && (value.is_a?(Fixnum) ? value.to_f : value).to_d
+        else type_cast_using_column(value, column)
+      end
+    end
+
+    def type_cast_using_column(value, column)
+      column ? column.type_cast(value) : value
+    end
+
+    def get_projection_name_from_chained_relations(relation = @relation)
+      if relation.respond_to?(:projections) && relation.projections.present?
+        relation.send(:select_clauses).join(', ')
+      elsif relation.respond_to?(:relation)
+        get_projection_name_from_chained_relations(relation.relation)
+      end
+    end
+
+  end
+end
diff --git a/activerecord/lib/active_record/relation/finder_methods.rb b/activerecord/lib/active_record/relation/finder_methods.rb
new file mode 100644
index 0000000000..7a1d6fc538
--- /dev/null
+++ b/activerecord/lib/active_record/relation/finder_methods.rb
@@ -0,0 +1,120 @@
+module ActiveRecord
+  module FinderMethods
+
+    def find(*ids, &block)
+      return to_a.find(&block) if block_given?
+
+      expects_array = ids.first.kind_of?(Array)
+      return ids.first if expects_array && ids.first.empty?
+
+      ids = ids.flatten.compact.uniq
+
+      case ids.size
+      when 0
+        raise RecordNotFound, "Couldn't find #{@klass.name} without an ID"
+      when 1
+        result = find_one(ids.first)
+        expects_array ? [ result ] : result
+      else
+        find_some(ids)
+      end
+    end
+
+    def exists?(id = nil)
+      relation = select("#{@klass.quoted_table_name}.#{@klass.primary_key}").limit(1)
+      relation = relation.where(@klass.primary_key => id) if id
+      relation.first ? true : false
+    end
+
+    def first
+      if loaded?
+        @records.first
+      else
+        @first ||= limit(1).to_a[0]
+      end
+    end
+
+    def last
+      if loaded?
+        @records.last
+      else
+        @last ||= reverse_order.limit(1).to_a[0]
+      end
+    end
+
+    protected
+
+    def find_by_attributes(match, attributes, *args)
+      conditions = attributes.inject({}) {|h, a| h[a] = args[attributes.index(a)]; h}
+      result = where(conditions).send(match.finder)
+
+      if match.bang? && result.blank?
+        raise RecordNotFound, "Couldn't find #{@klass.name} with #{conditions.to_a.collect {|p| p.join(' = ')}.join(', ')}"
+      else
+        result
+      end
+    end
+
+    def find_or_instantiator_by_attributes(match, attributes, *args)
+      guard_protected_attributes = false
+
+      if args[0].is_a?(Hash)
+        guard_protected_attributes = true
+        attributes_for_create = args[0].with_indifferent_access
+        conditions = attributes_for_create.slice(*attributes).symbolize_keys
+      else
+        attributes_for_create = conditions = attributes.inject({}) {|h, a| h[a] = args[attributes.index(a)]; h}
+      end
+
+      record = where(conditions).first
+
+      unless record
+        record = @klass.new { |r| r.send(:attributes=, attributes_for_create, guard_protected_attributes) }
+        yield(record) if block_given?
+        record.save if match.instantiator == :create
+      end
+
+      record
+    end
+
+    def find_one(id)
+      record = where(@klass.primary_key => id).first
+
+      unless record
+        conditions = where_clause(', ')
+        conditions = " [WHERE #{conditions}]" if conditions.present?
+        raise RecordNotFound, "Couldn't find #{@klass.name} with ID=#{id}#{conditions}"
+      end
+
+      record
+    end
+
+    def find_some(ids)
+      result = where(@klass.primary_key => ids).all
+
+      expected_size =
+        if @relation.taken && ids.size > @relation.taken
+          @relation.taken
+        else
+          ids.size
+        end
+
+      # 11 ids with limit 3, offset 9 should give 2 results.
+      if @relation.skipped && (ids.size - @relation.skipped < expected_size)
+        expected_size = ids.size - @relation.skipped
+      end
+
+      if result.size == expected_size
+        result
+      else
+        conditions = where_clause(', ')
+        conditions = " [WHERE #{conditions}]" if conditions.present?
+
+        error = "Couldn't find all #{@klass.name.pluralize} with IDs "
+        error << "(#{ids.join(", ")})#{conditions} (found #{result.size} results, but was looking for #{expected_size})"
+        raise RecordNotFound, error
+      end
+    end
+
+  end
+end
diff --git a/activerecord/lib/active_record/relation/query_methods.rb b/activerecord/lib/active_record/relation/query_methods.rb
new file mode 100644
index 0000000000..631c80da25
--- /dev/null
+++ b/activerecord/lib/active_record/relation/query_methods.rb
@@ -0,0 +1,132 @@
+module ActiveRecord
+  module QueryMethods
+
+    def preload(*associations)
+      spawn.tap {|r| r.preload_associations += Array.wrap(associations) }
+    end
+
+    def eager_load(*associations)
+      spawn.tap {|r| r.eager_load_associations += Array.wrap(associations) }
+    end
+
+    def readonly(status = true)
+      spawn.tap {|r| r.readonly = status }
+    end
+
+    def select(selects)
+      if selects.present?
+        relation = spawn(@relation.project(selects))
+        relation.readonly = @relation.joins(relation).present? ? false : @readonly
+        relation
+      else
+        spawn
+      end
+    end
+
+    def from(from)
+      from.present? ? spawn(@relation.from(from)) : spawn
+    end
+
+    def having(*args)
+      return spawn if args.blank?
+
+      if [String, Hash, Array].include?(args.first.class)
+        havings = @klass.send(:merge_conditions, args.size > 1 ? Array.wrap(args) : args.first)
+      else
+        havings = args.first
+      end
+
+      spawn(@relation.having(havings))
+    end
+
+    def group(groups)
+      groups.present? ? spawn(@relation.group(groups)) : spawn
+    end
+
+    def order(orders)
+      orders.present? ? spawn(@relation.order(orders)) : spawn
+    end
+
+    def lock(locks = true)
+      case locks
+      when String
+        spawn(@relation.lock(locks))
+      when TrueClass, NilClass
+        spawn(@relation.lock)
+      else
+        spawn
+      end
+    end
+
+    def reverse_order
+      relation = spawn
+      relation.instance_variable_set(:@orders, nil)
+
+      order_clause = @relation.send(:order_clauses).join(', ')
+      if order_clause.present?
+        relation.order(reverse_sql_order(order_clause))
+      else
+        relation.order("#{@klass.table_name}.#{@klass.primary_key} DESC")
+      end
+    end
+
+    def limit(limits)
+      limits.present? ? spawn(@relation.take(limits)) : spawn
+    end
+
+    def offset(offsets)
+      offsets.present? ? spawn(@relation.skip(offsets)) : spawn
+    end
+
+    def on(join)
+      spawn(@relation.on(join))
+    end
+
+    def joins(join, join_type = nil)
+      return spawn if join.blank?
+
+      join_relation = case join
+      when String
+        @relation.join(join)
+      when Hash, Array, Symbol
+        if @klass.send(:array_of_strings?, join)
+          @relation.join(join.join(' '))
+        else
+          @relation.join(@klass.send(:build_association_joins, join))
+        end
+      else
+        @relation.join(join, join_type)
+      end
+
+      spawn(join_relation).tap { |r| r.readonly = true }
+    end
+
+    def where(*args)
+      return spawn if args.blank?
+
+      if [String, Hash, Array].include?(args.first.class)
+        conditions = @klass.send(:merge_conditions, args.size > 1 ? Array.wrap(args) : args.first)
+        conditions = Arel::SqlLiteral.new(conditions) if conditions
+      else
+        conditions = args.first
+      end
+
+      spawn(@relation.where(conditions))
+    end
+
+    private
+
+    def reverse_sql_order(order_query)
+      order_query.to_s.split(/,/).each { |s|
+        if s.match(/\s(asc|ASC)$/)
+          s.gsub!(/\s(asc|ASC)$/, ' DESC')
+        elsif s.match(/\s(desc|DESC)$/)
+          s.gsub!(/\s(desc|DESC)$/, ' ASC')
+        else
+          s.concat(' DESC')
+        end
+      }.join(',')
+    end
+
+  end
+end