Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
Browse files

Introduce finder :joins with associations. Same :include syntax but w…

…ith inner rather than outer joins. Closes #10012.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@8054 5ecf4fe2-1ee6-0310-87b1-e25e094e27de
  • Loading branch information...
commit bef071dd0b6b634c5e8e49d8c1b9daa0baa4136c 1 parent 2283524
@jeremy jeremy authored
View
7 activerecord/CHANGELOG
@@ -1,5 +1,12 @@
*SVN*
+* Introduce finder :joins with associations. Same :include syntax but with inner rather than outer joins. #10012 [RubyRedRick]
+ # Find users with an avatar
+ User.find(:all, :joins => :avatar)
+
+ # Find posts with a high-rated comment.
+ Post.find(:all, :joins => :comments, :conditions => 'comments.rating > 3')
+
* Associations: speedup duplicate record check. #10011 [lifofifo]
* Make sure that << works on has_many associations on unsaved records. Closes #9989 [hasmanyjosh]
View
103 activerecord/lib/active_record/associations.rb
@@ -486,7 +486,63 @@ 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,
@@ -1121,7 +1177,13 @@ def association_constructor_method(constructor, reflection, association_proxy_cl
def find_with_associations(options = {})
catch :invalid_query do
- join_dependency = JoinDependency.new(self, merge_includes(scope(:find, :include), options[:include]), options[:joins])
+ 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])
rows = select_all_rows(options, join_dependency)
return join_dependency.instantiate(rows)
end
@@ -1375,8 +1437,9 @@ def create_extension_modules(association_id, block_extension, extensions)
class JoinDependency # :nodoc:
attr_reader :joins, :reflections, :table_aliases
- def initialize(base, associations, joins)
+ def initialize(base, associations, joins, ar_joins = nil)
@joins = [JoinBase.new(base, joins)]
+ @ar_joins = ar_joins
@associations = associations
@reflections = []
@base_records_hash = {}
@@ -1400,9 +1463,9 @@ 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)
+ construct(@base_records_hash[primary_id], @associations, join_associations.dup, row) unless @ar_joins
end
- remove_duplicate_results!(join_base.active_record, @base_records_in_order, @associations)
+ remove_duplicate_results!(join_base.active_record, @base_records_in_order, @associations) unless @ar_joins
return @base_records_in_order
end
@@ -1444,7 +1507,7 @@ 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 << JoinAssociation.new(reflection, self, parent)
+ @joins << (@ar_joins ? ARJoinAssociation : JoinAssociation).new(reflection, self, parent)
when Array
associations.each do |association|
build(association, parent)
@@ -1595,12 +1658,12 @@ def initialize(reflection, join_dependency, parent = nil)
def association_join
join = case reflection.macro
when :has_and_belongs_to_many
- " LEFT OUTER JOIN %s ON %s.%s = %s.%s " % [
+ " #{join_type} %s ON %s.%s = %s.%s " % [
table_alias_for(options[:join_table], aliased_join_table_name),
aliased_join_table_name,
options[:foreign_key] || reflection.active_record.to_s.foreign_key,
parent.aliased_table_name, reflection.active_record.primary_key] +
- " LEFT OUTER JOIN %s ON %s.%s = %s.%s " % [
+ " #{join_type} %s ON %s.%s = %s.%s " % [
table_name_and_alias, aliased_table_name, klass.primary_key,
aliased_join_table_name, options[:association_foreign_key] || klass.to_s.foreign_key
]
@@ -1658,13 +1721,13 @@ def association_join
end
end
- " LEFT OUTER JOIN %s ON (%s.%s = %s.%s%s%s%s) " % [
+ " #{join_type} %s ON (%s.%s = %s.%s%s%s%s) " % [
table_alias_for(through_reflection.klass.table_name, aliased_join_table_name),
parent.aliased_table_name, reflection.active_record.connection.quote_column_name(parent.primary_key),
aliased_join_table_name, reflection.active_record.connection.quote_column_name(jt_foreign_key),
jt_as_extra, jt_source_extra, jt_sti_extra
] +
- " LEFT OUTER JOIN %s ON (%s.%s = %s.%s%s) " % [
+ " #{join_type} %s ON (%s.%s = %s.%s%s) " % [
table_name_and_alias,
aliased_table_name, reflection.active_record.connection.quote_column_name(first_key),
aliased_join_table_name, reflection.active_record.connection.quote_column_name(second_key),
@@ -1672,7 +1735,7 @@ def association_join
]
when reflection.options[:as] && [:has_many, :has_one].include?(reflection.macro)
- " LEFT OUTER JOIN %s ON %s.%s = %s.%s AND %s.%s = %s" % [
+ " #{join_type} %s ON %s.%s = %s.%s AND %s.%s = %s" % [
table_name_and_alias,
aliased_table_name, "#{reflection.options[:as]}_id",
parent.aliased_table_name, parent.primary_key,
@@ -1681,14 +1744,14 @@ def association_join
]
else
foreign_key = options[:foreign_key] || reflection.active_record.name.foreign_key
- " LEFT OUTER JOIN %s ON %s.%s = %s.%s " % [
+ " #{join_type} %s ON %s.%s = %s.%s " % [
table_name_and_alias,
aliased_table_name, foreign_key,
parent.aliased_table_name, parent.primary_key
]
end
when :belongs_to
- " LEFT OUTER JOIN %s ON %s.%s = %s.%s " % [
+ " #{join_type} %s ON %s.%s = %s.%s " % [
table_name_and_alias, aliased_table_name, reflection.klass.primary_key,
parent.aliased_table_name, options[:foreign_key] || klass.to_s.foreign_key
]
@@ -1723,7 +1786,19 @@ def table_name_and_alias
def interpolate_sql(sql)
instance_eval("%@#{sql.gsub('@', '\@')}@")
- end
+ end
+
+ private
+ def join_type
+ "LEFT OUTER JOIN"
+ end
+
+ end
+ class ARJoinAssociation < JoinAssociation
+ private
+ def join_type
+ "INNER JOIN"
+ end
end
end
end
View
34 activerecord/lib/active_record/base.rb
@@ -380,9 +380,11 @@ 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>: 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>: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>: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
@@ -428,8 +430,17 @@ 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)
@@ -1020,8 +1031,17 @@ 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] ?
+ records = scoped?(:find, :include) || options[:include] || scoped?(:find, :ar_joins) || (options[:ar_joins]) ?
find_with_associations(options) :
find_by_sql(construct_finder_sql(options))
@@ -1445,7 +1465,13 @@ 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
@@ -1458,7 +1484,7 @@ 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 key == :include && merge
+ elsif ([:include, :ar_joins].include?(key)) && merge
hash[method][key] = merge_includes(hash[method][key], params[key]).uniq
else
hash[method][key] = hash[method][key] || params[key]
View
19 activerecord/lib/active_record/calculations.rb
@@ -15,8 +15,11 @@ 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>: 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>: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>: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.
@@ -109,7 +112,9 @@ 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
@@ -149,8 +154,14 @@ def construct_calculation_sql(operation, column_name, options) #:nodoc:
operation = operation.to_s.downcase
options = options.symbolize_keys
- scope = scope(:find)
+ scope = scope(:find)
+ if scope && scope[:ar_joins]
+ scope = scope.dup
+ options = options.dup
+ options[:ar_joins] = scope.delete(:ar_joins)
+ end
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'
@@ -173,7 +184,7 @@ def construct_calculation_sql(operation, column_name, options) #:nodoc:
sql << " FROM (SELECT DISTINCT #{column_name}" if use_workaround
sql << " FROM #{table_name} "
if merged_includes.any?
- join_dependency = ActiveRecord::Associations::ClassMethods::JoinDependency.new(self, merged_includes, options[:joins])
+ join_dependency = ActiveRecord::Associations::ClassMethods::JoinDependency.new(self, merged_includes, options[:joins], options[:ar_joins])
sql << join_dependency.join_associations.collect{|join| join.association_join }.join
end
add_joins!(sql, options, scope)
View
158 activerecord/test/associations/ar_joins_test.rb
@@ -0,0 +1,158 @@
+require 'abstract_unit'
+require 'fixtures/post'
+require 'fixtures/comment'
+require 'fixtures/author'
+require 'fixtures/category'
+require 'fixtures/categorization'
+require 'fixtures/company'
+require 'fixtures/topic'
+require 'fixtures/reply'
+require 'fixtures/developer'
+require 'fixtures/project'
+
+class ArJoinsTest < Test::Unit::TestCase
+ fixtures :authors, :posts, :comments, :categories, :categories_posts, :people,
+ :developers, :projects, :developers_projects,
+ :categorizations, :companies, :accounts, :topics
+
+ def test_ar_joins
+ authors = Author.find(:all, :joins => :posts, :conditions => ['posts.type = ?', "Post"])
+ assert_not_equal(0 , authors.length)
+ authors.each do |author|
+ assert !(author.send(:instance_variables).include? "@posts")
+ assert(!author.readonly?, "non-string join value produced read-only result.")
+ end
+ end
+
+ def test_ar_joins_with_cascaded_two_levels
+ authors = Author.find(:all, :joins=>{:posts=>:comments})
+ assert_equal(2, authors.length)
+ authors.each do |author|
+ assert !(author.send(:instance_variables).include? "@posts")
+ assert(!author.readonly?, "non-string join value produced read-only result.")
+ end
+ authors = Author.find(:all, :joins=>{:posts=>:comments}, :conditions => ["comments.body = ?", "go crazy" ])
+ assert_equal(1, authors.length)
+ authors.each do |author|
+ assert !(author.send(:instance_variables).include? "@posts")
+ assert(!author.readonly?, "non-string join value produced read-only result.")
+ end
+ end
+
+
+ def test_ar_joins_with_complex_conditions
+ authors = Author.find(:all, :joins=>{:posts=>[:comments, :categories]},
+ :conditions => ["categories.name = ? AND posts.title = ?", "General", "So I was thinking"]
+ )
+ assert_equal(1, authors.length)
+ authors.each do |author|
+ assert !(author.send(:instance_variables).include? "@posts")
+ assert(!author.readonly?, "non-string join value produced read-only result.")
+ end
+ assert_equal("David", authors.first.name)
+ end
+
+ def test_ar_join_with_has_many_and_limit_and_scoped_and_explicit_conditions
+ Post.with_scope(:find => { :conditions => "1=1" }) do
+ posts = authors(:david).posts.find(:all,
+ :joins => :comments,
+ :conditions => "comments.body like 'Normal%' OR comments.#{QUOTED_TYPE}= 'SpecialComment'",
+ :limit => 2
+ )
+ assert_equal 2, posts.size
+
+ count = Post.count(
+ :joins => [ :comments, :author ],
+ :conditions => "authors.name = 'David' AND (comments.body like 'Normal%' OR comments.#{QUOTED_TYPE}= 'SpecialComment')",
+ :limit => 2
+ )
+ assert_equal count, posts.size
+ end
+ end
+
+ def test_ar_join_with_scoped_order_using_association_limiting_without_explicit_scope
+ posts_with_explicit_order = Post.find(:all, :conditions => 'comments.id is not null', :joins => :comments, :order => 'posts.id DESC', :limit => 2)
+ posts_with_scoped_order = Post.with_scope(:find => {:order => 'posts.id DESC'}) do
+ Post.find(:all, :conditions => 'comments.id is not null', :joins => :comments, :limit => 2)
+ end
+ assert_equal posts_with_explicit_order, posts_with_scoped_order
+ end
+
+ def test_scoped_find_include
+ # with the include, will retrieve only developers for the given project
+ scoped_developers = Developer.with_scope(:find => { :joins => :projects }) do
+ Developer.find(:all, :conditions => 'projects.id = 2')
+ end
+ assert scoped_developers.include?(developers(:david))
+ assert !scoped_developers.include?(developers(:jamis))
+ assert_equal 1, scoped_developers.size
+ end
+
+
+ def test_nested_scoped_find_ar_join
+ Developer.with_scope(:find => { :joins => :projects }) do
+ Developer.with_scope(:find => { :conditions => "projects.id = 2" }) do
+ assert_equal('David', Developer.find(:first).name)
+ end
+ end
+ end
+
+ def test_nested_scoped_find_merged_ar_join
+ # :include's remain unique and don't "double up" when merging
+ Developer.with_scope(:find => { :joins => :projects, :conditions => "projects.id = 2" }) do
+ Developer.with_scope(:find => { :joins => :projects }) do
+ assert_equal 1, Developer.instance_eval('current_scoped_methods')[:find][:ar_joins].length
+ assert_equal('David', Developer.find(:first).name)
+ end
+ end
+ # the nested scope doesn't remove the first :include
+ Developer.with_scope(:find => { :joins => :projects, :conditions => "projects.id = 2" }) do
+ Developer.with_scope(:find => { :joins => [] }) do
+ assert_equal 1, Developer.instance_eval('current_scoped_methods')[:find][:ar_joins].length
+ assert_equal('David', Developer.find(:first).name)
+ end
+ end
+ # mixing array and symbol include's will merge correctly
+ Developer.with_scope(:find => { :joins => [:projects], :conditions => "projects.id = 2" }) do
+ Developer.with_scope(:find => { :joins => :projects }) do
+ assert_equal 1, Developer.instance_eval('current_scoped_methods')[:find][:ar_joins].length
+ assert_equal('David', Developer.find(:first).name)
+ end
+ end
+ end
+
+ def test_nested_scoped_find_replace_include
+ Developer.with_scope(:find => { :joins => :projects }) do
+ Developer.with_exclusive_scope(:find => { :joins => [] }) do
+ assert_equal 0, Developer.instance_eval('current_scoped_methods')[:find][:ar_joins].length
+ end
+ end
+ end
+
+#
+# Calculations
+#
+ def test_count_with_ar_joins
+ assert_equal(2, Author.count(:joins => :posts, :conditions => ['posts.type = ?', "Post"]))
+ assert_equal(1, Author.count(:joins => :posts, :conditions => ['posts.type = ?', "SpecialPost"]))
+ end
+
+ def test_should_get_maximum_of_field_with_joins
+ assert_equal 50, Account.maximum(:credit_limit, :joins=> :firm, :conditions => "companies.name != 'Summit'")
+ end
+
+ def test_should_get_maximum_of_field_with_scoped_include
+ Account.with_scope :find => { :joins => :firm, :conditions => "companies.name != 'Summit'" } do
+ assert_equal 50, Account.maximum(:credit_limit)
+ end
+ end
+
+ def test_should_not_modify_options_when_using_ar_joins_on_count
+ options = {:conditions => 'companies.id > 1', :joins => :firm}
+ options_copy = options.dup
+
+ Account.count(:all, options)
+ assert_equal options_copy, options
+ end
+
+end
Please sign in to comment.
Something went wrong with that request. Please try again.