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提交 bef071dd 编写于 作者: J Jeremy Kemper
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Introduce finder :joins with associations. Same :include syntax but with inner... 

Introduce finder :joins with associations. Same :include syntax but with inner rather than outer joins. Closes #10012.


git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@8054 5ecf4fe2-1ee6-0310-87b1-e25e094e27de
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activerecord/CHANGELOG
浏览文件 @ bef071dd
*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]
......
activerecord/lib/active_record/associations.rb
浏览文件 @ bef071dd
......@@ -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
......
activerecord/lib/active_record/base.rb
浏览文件 @ bef071dd
......@@ -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]
......
activerecord/lib/active_record/calculations.rb
浏览文件 @ bef071dd
......@@ -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)
......
activerecord/test/associations/ar_joins_test.rb 0 → 100644
浏览文件 @ bef071dd
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
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