Skip to content

Commit

Permalink
Address shortcomings of changeset [8054] [protocool]
Browse files Browse the repository at this point in the history 
git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@8109 5ecf4fe2-1ee6-0310-87b1-e25e094e27de
  • Loading branch information
@dhh
dhh committed Nov 7, 2007
1 parent 31e2a2d commit 37adea6
Show file tree
Hide file tree
Showing 5 changed files with 128 additions and 277 deletions.
97 changes: 24 additions & 73 deletions activerecord/lib/active_record/associations.rb
View file
Expand Up @@ -486,63 +486,7 @@ def clear_association_cache #:nodoc:
#
# When eager loaded, conditions are interpolated in the context of the model class, not the model instance. Conditions are lazily interpolated
# before the actual model exists.
#
# == Adding Joins For Associations to Queries Using the :joins option
#
# ActiveRecord::Base#find provides a :joins option, which takes either a string or values accepted by the :include option.
# if the value is a string, the it should contain a SQL fragment containing a join clause.
#
# Non-string values of :joins will add an automatic join clause to the query in the same way that the :include option does but with two critical
# differences:
#
# 1. A normal (inner) join will be performed instead of the outer join generated by :include.
# this means that only objects which have objects attached to the association will be included in the result.
# For example, suppose we have the following tables (in yaml format):
#
# Authors
# fred:
# id: 1
# name: Fred
# steve:
# id: 2
# name: Steve
#
# Contributions
# only:
# id: 1
# author_id: 1
# description: Atta Boy Letter for Steve
# date: 2007-10-27 14:09:54
#
# and corresponding AR Classes
#
# class Author: < ActiveRecord::Base
# has_many :contributions
# end
#
# class Contribution < ActiveRecord::Base
# belongs_to :author
# end
#
# The query Author.find(:all) will return both authors, but Author.find(:all, :joins => :contributions) will
# only return authors who have at least one contribution, in this case only the first.
# This is only a degenerate case of the more typical use of :joins with a non-string value.
# For example to find authors who have at least one contribution before a certain date we can use:
#
# Author.find(:all, :joins => :contributions, :conditions => ["contributions.date <= ?", 1.week.ago.to_s(:db)])
#
# 2. Only instances of the class to which the find is sent will be instantiated. ActiveRecord objects will not
# be instantiated for rows reached through the associations.
#
# The difference between using :joins vs :include to name associated records is that :joins allows associated tables to
# participate in selection criteria in the query without incurring the overhead of instantiating associated objects.
# This can be important when the number of associated objects in the database is large, and they will not be used, or
# only those associated with a paricular object or objects will be used after the query, making two queries more
# efficient than one.
#
# Note that while using a string value for :joins marks the result objects as read-only, the objects resulting
# from a call to find with a non-string :joins option value will be writable.
#
#
# == Table Aliasing
#
# ActiveRecord uses table aliasing in the case that a table is referenced multiple times in a join. If a table is referenced only once,
Expand Down Expand Up @@ -1177,13 +1121,7 @@ def association_constructor_method(constructor, reflection, association_proxy_cl

def find_with_associations(options = {})
catch :invalid_query do
if ar_joins = scope(:find, :ar_joins)
options = options.dup
options[:ar_joins] = ar_joins
end
includes = merge_includes(scope(:find, :include), options[:include])
includes = merge_includes(includes, options[:ar_joins])
join_dependency = JoinDependency.new(self, includes, options[:joins], options[:ar_joins])
join_dependency = JoinDependency.new(self, merge_includes(scope(:find, :include), options[:include]), options[:joins])
rows = select_all_rows(options, join_dependency)
return join_dependency.instantiate(rows)
end
Expand Down Expand Up @@ -1437,9 +1375,8 @@ def create_extension_modules(association_id, block_extension, extensions)
class JoinDependency # :nodoc:
attr_reader :joins, :reflections, :table_aliases

def initialize(base, associations, joins, ar_joins = nil)
def initialize(base, associations, joins)
@joins = [JoinBase.new(base, joins)]
@ar_joins = ar_joins
@associations = associations
@reflections = []
@base_records_hash = {}
Expand All @@ -1463,9 +1400,9 @@ def instantiate(rows)
unless @base_records_hash[primary_id]
@base_records_in_order << (@base_records_hash[primary_id] = join_base.instantiate(row))
end
construct(@base_records_hash[primary_id], @associations, join_associations.dup, row) unless @ar_joins
construct(@base_records_hash[primary_id], @associations, join_associations.dup, row)
end
remove_duplicate_results!(join_base.active_record, @base_records_in_order, @associations) unless @ar_joins
remove_duplicate_results!(join_base.active_record, @base_records_in_order, @associations)
return @base_records_in_order
end

Expand Down Expand Up @@ -1507,7 +1444,7 @@ def build(associations, parent = nil)
reflection = parent.reflections[associations.to_s.intern] or
raise ConfigurationError, "Association named '#{ associations }' was not found; perhaps you misspelled it?"
@reflections << reflection
@joins << (@ar_joins ? ARJoinAssociation : JoinAssociation).new(reflection, self, parent)
@joins << build_join_association(reflection, parent)
when Array
associations.each do |association|
build(association, parent)
Expand All @@ -1522,6 +1459,11 @@ def build(associations, parent = nil)
end
end

# overridden in InnerJoinDependency subclass
def build_join_association(reflection, parent)
JoinAssociation.new(reflection, self, parent)
end

def construct(parent, associations, joins, row)
case associations
when Symbol, String
Expand Down Expand Up @@ -1786,21 +1728,30 @@ def table_name_and_alias

def interpolate_sql(sql)
instance_eval("%@#{sql.gsub('@', '\@')}@")
end
end

private

private
def join_type
"LEFT OUTER JOIN"
end

end
class ARJoinAssociation < JoinAssociation
end

class InnerJoinDependency < JoinDependency # :nodoc:
protected
def build_join_association(reflection, parent)
InnerJoinAssociation.new(reflection, self, parent)
end

class InnerJoinAssociation < JoinAssociation
private
def join_type
"INNER JOIN"
end
end
end

end
end
end
43 changes: 12 additions & 31 deletions activerecord/lib/active_record/base.rb
View file
Expand Up @@ -380,11 +380,10 @@ class << self # Class methods
# * <tt>:group</tt>: An attribute name by which the result should be grouped. Uses the GROUP BY SQL-clause.
# * <tt>:limit</tt>: An integer determining the limit on the number of rows that should be returned.
# * <tt>:offset</tt>: An integer determining the offset from where the rows should be fetched. So at 5, it would skip rows 0 through 4.
# * <tt>:joins</tt>: Either an SQL fragment for additional joins like "LEFT JOIN comments ON comments.post_id = id". (Rarely needed).
# or names associations in the same form used for the :include option.
# If the value is a string, then the records will be returned read-only since they will have attributes that do not correspond to the table's columns.
# * <tt>:joins</tt>: An SQL fragment for additional joins like "LEFT JOIN comments ON comments.post_id = id" (Rarely needed).
# Accepts named associations in the form of :include, which will perform an INNER JOIN on the associated table(s).
# The records will be returned read-only since they will have attributes that do not correspond to the table's columns.
# Pass :readonly => false to override.
# See adding joins for associations under Association.
# * <tt>:include</tt>: Names associations that should be loaded alongside using LEFT OUTER JOINs. The symbols named refer
# to already defined associations. See eager loading under Associations.
# * <tt>:select</tt>: By default, this is * as in SELECT * FROM, but can be changed if you for example want to do a join, but not
Expand Down Expand Up @@ -430,17 +429,8 @@ class << self # Class methods
# end
def find(*args)
options = args.extract_options!
# Note: we extract any :joins option with a non-string value from the options, and turn it into
# an internal option :ar_joins. This allows code called from her to find the ar_joins, and
# it bypasses marking the result as read_only.
# A normal string join marks the result as read-only because it contains attributes from joined tables
# which are not in the base table and therefore prevent the result from being saved.
# In the case of an ar_join, the JoinDependency created to instantiate the results eliminates these
# bogus attributes. See JoinDependency#instantiate, and JoinBase#instantiate in associations.rb.
options, ar_joins = *extract_ar_join_from_options(options)
validate_find_options(options)
set_readonly_option!(options)
options[:ar_joins] = ar_joins if ar_joins

case args.first
when :first then find_initial(options)
Expand Down Expand Up @@ -1038,17 +1028,8 @@ def find_initial(options)
find_every(options).first
end

# If options contains :joins, with a non-string value
# remove it from options
# return the updated or unchanged options, and the ar_join value or nil
def extract_ar_join_from_options(options)
new_options = options.dup
join_option = new_options.delete(:joins)
(join_option && !join_option.kind_of?(String)) ? [new_options, join_option] : [options, nil]
end

def find_every(options)
records = scoped?(:find, :include) || options[:include] || scoped?(:find, :ar_joins) || (options[:ar_joins]) ?
records = scoped?(:find, :include) || options[:include] ?
find_with_associations(options) :
find_by_sql(construct_finder_sql(options))

Expand Down Expand Up @@ -1246,7 +1227,13 @@ def add_lock!(sql, options, scope = :auto)
def add_joins!(sql, options, scope = :auto)
scope = scope(:find) if :auto == scope
join = (scope && scope[:joins]) || options[:joins]
sql << " #{join} " if join
case join
when Symbol, Hash, Array
join_dependency = ActiveRecord::Associations::ClassMethods::InnerJoinDependency.new(self, join, nil)
sql << " #{join_dependency.join_associations.collect{|join| join.association_join }.join} "
else
sql << " #{join} "
end
end

# Adds a sanitized version of +conditions+ to the +sql+ string. Note that the passed-in +sql+ string is changed.
Expand Down Expand Up @@ -1472,13 +1459,7 @@ def with_scope(method_scoping = {}, action = :merge, &block)

if f = method_scoping[:find]
f.assert_valid_keys(VALID_FIND_OPTIONS)
# see note about :joins and :ar_joins in ActiveRecord::Base#find
f, ar_joins = *extract_ar_join_from_options(f)
set_readonly_option! f
if ar_joins
f[:ar_joins] = ar_joins
method_scoping[:find] = f
end
end

# Merge scopings
Expand All @@ -1491,7 +1472,7 @@ def with_scope(method_scoping = {}, action = :merge, &block)
merge = hash[method][key] && params[key] # merge if both scopes have the same key
if key == :conditions && merge
hash[method][key] = [params[key], hash[method][key]].collect{ |sql| "( %s )" % sanitize_sql(sql) }.join(" AND ")
elsif ([:include, :ar_joins].include?(key)) && merge
elsif key == :include && merge
hash[method][key] = merge_includes(hash[method][key], params[key]).uniq
else
hash[method][key] = hash[method][key] || params[key]
Expand Down
19 changes: 4 additions & 15 deletions activerecord/lib/active_record/calculations.rb
View file
Expand Up @@ -15,11 +15,8 @@ module ClassMethods
# The third approach, count using options, accepts an option hash as the only parameter. The options are:
#
# * <tt>:conditions</tt>: An SQL fragment like "administrator = 1" or [ "user_name = ?", username ]. See conditions in the intro.
# * <tt>:joins</tt>: Either an SQL fragment for additional joins like "LEFT JOIN comments ON comments.post_id = id". (Rarely needed).
# or names associations in the same form used for the :include option.
# If the value is a string, then the records will be returned read-only since they will have attributes that do not correspond to the table's columns.
# Pass :readonly => false to override.
# See adding joins for associations under Association.
# * <tt>:joins</tt>: An SQL fragment for additional joins like "LEFT JOIN comments ON comments.post_id = id". (Rarely needed).
# The records will be returned read-only since they will have attributes that do not correspond to the table's columns.
# * <tt>:include</tt>: Named associations that should be loaded alongside using LEFT OUTER JOINs. The symbols named refer
# to already defined associations. When using named associations count returns the number DISTINCT items for the model you're counting.
# See eager loading under Associations.
Expand Down Expand Up @@ -112,9 +109,7 @@ def sum(column_name, options = {})
# Person.minimum(:age, :conditions => ['last_name != ?', 'Drake']) # Selects the minimum age for everyone with a last name other than 'Drake'
# Person.minimum(:age, :having => 'min(age) > 17', :group => :last_name) # Selects the minimum age for any family without any minors
def calculate(operation, column_name, options = {})
options, ar_joins = *extract_ar_join_from_options(options)
validate_calculation_options(operation, options)
options[:ar_joins] = ar_joins if ar_joins
column_name = options[:select] if options[:select]
column_name = '*' if column_name == :all
column = column_for column_name
Expand Down Expand Up @@ -154,14 +149,8 @@ def construct_calculation_sql(operation, column_name, options) #:nodoc:
operation = operation.to_s.downcase
options = options.symbolize_keys

scope = scope(:find)
if scope && scope[:ar_joins]
scope = scope.dup
options = options.dup
options[:ar_joins] = scope.delete(:ar_joins)
end
scope = scope(:find)
merged_includes = merge_includes(scope ? scope[:include] : [], options[:include])
merged_includes = merge_includes(merged_includes, options[:ar_joins])
aggregate_alias = column_alias_for(operation, column_name)

if operation == 'count'
Expand All @@ -184,7 +173,7 @@ def construct_calculation_sql(operation, column_name, options) #:nodoc:
sql << " FROM (SELECT DISTINCT #{column_name}" if use_workaround
sql << " FROM #{connection.quote_table_name(table_name)} "
if merged_includes.any?
join_dependency = ActiveRecord::Associations::ClassMethods::JoinDependency.new(self, merged_includes, options[:joins], options[:ar_joins])
join_dependency = ActiveRecord::Associations::ClassMethods::JoinDependency.new(self, merged_includes, options[:joins])
sql << join_dependency.join_associations.collect{|join| join.association_join }.join
end
add_joins!(sql, options, scope)
Expand Down

0 comments on commit 37adea6

Please sign in to comment.