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Added support for has_and_belongs_to_many associations in eager loading

#1064 [Dan Peterson]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@1132 5ecf4fe2-1ee6-0310-87b1-e25e094e27de
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1 parent fdd2681 commit 057cf4918bbc3573321f610a12c29676373b8f0c @dhh dhh committed Apr 10, 2005
@@ -628,67 +628,154 @@ def add_multiple_associated_save_callbacks(association_name)
def find_with_associations(options = {})
- reflections = [ options[:include] ].flatten.collect { |association| reflect_on_association(association) }
- rows = connection.select_all(construct_finder_sql_with_included_associations(options, reflections), "#{name} Load Including Associations")
- records = rows.collect { |row| instantiate(extract_record(table_name, row)) }.uniq
+ reflections = reflect_on_included_associations(options[:include])
+ schema_abbreviations = generate_schema_abbreviations(reflections)
+ primary_key_table = generate_primary_key_table(reflections, schema_abbreviations)
- reflections.each do |reflection|
- records.each do |record|
+ rows = select_all_rows(options, schema_abbreviations, reflections)
+ records = extract_and_instantiate_records(schema_abbreviations, rows)
+
+ assign_associations_to_records(rows, records, reflections, schema_abbreviations, primary_key_table)
+
+ return records
+ end
+
+ def assign_associations_to_records(rows, records, reflections, schema_abbreviations, primary_key_table)
+ records.each do |record|
+ reflections.each do |reflection|
case reflection.macro
- when :has_many
- record.send(reflection.name).target = extract_association_for_record(record, rows, reflection)
+ when :has_many, :has_and_belongs_to_many
+ record.send(reflection.name).target =
+ extract_association_for_record(record, schema_abbreviations, primary_key_table, rows, reflection)
when :has_one, :belongs_to
- record.send("set_#{reflection.name}_target", extract_association_for_record(record, rows, reflection).first)
+ record.send(
+ "set_#{reflection.name}_target",
+ extract_association_for_record(record, schema_abbreviations, primary_key_table, rows, reflection).first
+ )
end
end
end
+ end
+
+ def generate_schema_abbreviations(reflections)
+ schema = [ [ table_name, columns.collect { |c| c.name } ] ]
+ schema += reflections.collect { |r| [ r.klass.table_name, r.klass.columns.collect { |c| c.name } ] }
+
+ schema_abbreviations = {}
+ schema.each_with_index do |table_and_columns, i|
+ table, columns = table_and_columns
+ columns.each_with_index { |column, j| schema_abbreviations["t#{i}_r#{j}"] = [ table, column ] }
+ end
- return records
+ return schema_abbreviations
end
- def construct_finder_sql_with_included_associations(options, reflections)
- sql = "SELECT #{selected_columns(table_name, columns)}"
- reflections.each { |reflection| sql << ", #{selected_columns(reflection.klass.table_name, reflection.klass.columns)}" }
- sql << " FROM #{table_name} "
-
- reflections.each do |reflection|
- case reflection.macro
- when :has_many, :has_one
- sql << " LEFT JOIN #{reflection.klass.table_name} ON " +
- "#{reflection.klass.table_name}.#{reflection.options[:foreign_key] || table_name.classify.foreign_key} = #{table_name}.#{primary_key} "
- when :belongs_to
- sql << " LEFT JOIN #{reflection.klass.table_name} ON " +
- "#{reflection.klass.table_name}.#{reflection.klass.primary_key} = #{table_name}.#{reflection.options[:foreign_key] || reflection.klass.table_name.classify.foreign_key} "
- end
+ def generate_primary_key_table(reflections, schema_abbreviations)
+ primary_key_lookup_table = {}
+ primary_key_lookup_table[table_name] =
+ schema_abbreviations.find { |cn, tc| tc == [ table_name, primary_key ] }.first
+
+ reflections.collect do |reflection|
+ primary_key_lookup_table[reflection.klass.table_name] = schema_abbreviations.find { |cn, tc|
+ tc == [ reflection.klass.table_name, reflection.klass.primary_key ]
+ }.first
end
+
+ return primary_key_lookup_table
+ end
+
+ def construct_finder_sql_with_included_associations(options, schema_abbreviations, reflections)
+ habtm_associations = reflections.find_all { |r| r.macro == :has_and_belongs_to_many }
+
+ sql = "SELECT #{column_aliases(schema_abbreviations)} FROM #{table_name}"
+ add_habtm_join_tables!(habtm_associations, sql)
+ sql << " "
+
+ add_association_joins!(reflections, sql)
sql << "#{options[:joins]} " if options[:joins]
+
+ add_habtm_conditions!(habtm_associations, options)
add_conditions!(sql, options[:conditions])
+
sql << "ORDER BY #{options[:order]} " if options[:order]
return sanitize_sql(sql)
end
- def extract_association_for_record(record, rows, reflection)
- association = rows.collect do |row|
- if row["#{table_name}__#{primary_key}"] == record.id.to_s && !row["#{reflection.klass.table_name}__#{reflection.klass.primary_key}"].nil?
- reflection.klass.send(:instantiate, extract_record(reflection.klass.table_name, row))
+ def column_aliases(schema_abbreviations)
+ schema_abbreviations.collect { |cn, tc| "#{tc.join(".")} AS #{cn}" }.join(", ")
+ end
+
+ def add_habtm_join_tables!(habtm_associations, sql)
+ return if habtm_associations.empty?
+ sql << ", " + habtm_associations.collect { |a| [ a.klass.table_name, a.options[:join_table] ] }.join(", ")
+ end
+
+ def add_habtm_conditions!(habtm_associations, options)
+ return if habtm_associations.empty?
+ options[:conditions] = [
+ options[:conditions],
+ habtm_associations.collect { |r|
+ join_table = r.options[:join_table]
+ "#{join_table}.#{table_name.classify.foreign_key} = #{table_name}.#{primary_key} AND " +
+ "#{join_table}.#{r.klass.table_name.classify.foreign_key} = #{r.klass.table_name}.#{r.klass.primary_key}"
+ }
+ ].compact.join(" AND ")
+ end
+
+ def add_association_joins!(reflections, sql)
+ reflections.each { |reflection| sql << association_join(reflection) }
+ end
+
+ def association_join(reflection)
+ case reflection.macro
+ when :has_many, :has_one
+ " LEFT JOIN #{reflection.klass.table_name} ON " +
+ "#{reflection.klass.table_name}.#{reflection.options[:foreign_key] || table_name.classify.foreign_key} = " +
+ "#{table_name}.#{primary_key} "
+ when :belongs_to
+ " LEFT JOIN #{reflection.klass.table_name} ON " +
+ "#{reflection.klass.table_name}.#{reflection.klass.primary_key} = " +
+ "#{table_name}.#{reflection.options[:foreign_key] || reflection.klass.table_name.classify.foreign_key} "
+ else
+ ""
+ end
+ end
+
+
+ def extract_and_instantiate_records(schema_abbreviations, rows)
+ rows.collect { |row| instantiate(extract_record(schema_abbreviations, table_name, row)) }.uniq
+ end
+
+ def extract_association_for_record(record, schema_abbreviations, primary_key_table, rows, reflection)
+ association = rows.collect do |row|
+ if row[primary_key_table[table_name]].to_s == record.id.to_s && !row[primary_key_table[reflection.klass.table_name]].nil?
+ reflection.klass.send(:instantiate, extract_record(schema_abbreviations, reflection.klass.table_name, row))
end
end
return association.uniq.compact
end
- def extract_record(table_name, row)
+ def extract_record(schema_abbreviations, table_name, row)
row.inject({}) do |record, pair|
- prefix, column_name = pair.first.split("__")
+ prefix, column_name = schema_abbreviations[pair.first]
record[column_name] = pair.last if prefix == table_name
record
end
end
- def selected_columns(table_name, columns)
- columns.collect { |column| "#{table_name}.#{column.name} as #{table_name}__#{column.name}" }.join(", ")
+
+ def reflect_on_included_associations(associations)
+ [ associations ].flatten.collect { |association| reflect_on_association(association) }
+ end
+
+ def select_all_rows(options, schema_abbreviations, reflections)
+ connection.select_all(
+ construct_finder_sql_with_included_associations(options, schema_abbreviations, reflections),
+ "#{name} Load Including Associations"
+ )
end
end
end
@@ -2,9 +2,10 @@
require 'fixtures/post'
require 'fixtures/comment'
require 'fixtures/author'
+require 'fixtures/category'
class EagerAssociationTest < Test::Unit::TestCase
- fixtures :posts, :comments, :authors
+ fixtures :posts, :comments, :authors, :categories, :categories_posts
def test_loading_with_one_association
posts = Post.find(:all, :include => :comments)
@@ -17,8 +18,9 @@ def test_loading_with_one_association
end
def test_loading_with_multiple_associations
- posts = Post.find(:all, :include => [ :comments, :author ])
+ posts = Post.find(:all, :include => [ :comments, :author, :categories ])
assert_equal 2, posts.first.comments.size
+ assert_equal 2, posts.first.categories.size
assert_equal @greetings.body, posts.first.comments.first.body
end
@@ -32,10 +34,17 @@ def test_eager_association_loading_with_belongs_to
assert_equal @welcome.title, comments.first.post.title
assert_equal @thinking.title, comments.last.post.title
end
+
+ def test_eager_association_loading_with_habtm
+ posts = Post.find(:all, :include => :categories)
+ assert_equal 2, posts.first.categories.size
+ assert_equal 1, posts.last.categories.size
+ assert_equal @technology.name, posts.first.categories.last.name
+ assert_equal @general.name, posts.last.categories.first.name
+ end
def test_eager_with_inheritance
posts = SpecialPost.find(:all, :include => [ :comments ])
- end
-
+ end
end
@@ -0,0 +1,7 @@
+general:
+ id: 1
+ name: General
+
+technology:
+ id: 2
+ name: Technology
@@ -0,0 +1,11 @@
+general_welcome:
+ category_id: 1
+ post_id: 1
+
+technology_welcome:
+ category_id: 2
+ post_id: 1
+
+general_thinking:
+ category_id: 1
+ post_id: 2
@@ -0,0 +1,3 @@
+class Category < ActiveRecord::Base
+ has_and_belongs_to_many :posts
+end
@@ -19,4 +19,6 @@ DROP TABLE posts;
DROP TABLE comments;
DROP TABLE authors;
DROP TABLE tasks;
+DROP TABLE categories;
+DROP TABLE categories_posts;
@@ -154,3 +154,13 @@ CREATE TABLE tasks (
starting timestamp default NULL,
ending timestamp default NULL
);
+
+CREATE TABLE categories (
+ id int generated by default as identity (start with +10000),
+ name varchar(255) NOT NULL
+);
+
+CREATE TABLE categories_posts (
+ category_id int NOT NULL,
+ post_id int NOT NULL
+);
@@ -1,37 +0,0 @@
-DROP TABLE accounts;
-DROP SEQUENCE accounts_id;
-DROP TABLE companies;
-DROP SEQUENCE companies_id;
-DROP TABLE topics;
-DROP SEQUENCE topics_id;
-DROP TABLE developers;
-DROP SEQUENCE developers_id;
-DROP TABLE projects;
-DROP SEQUENCE projects_id;
-DROP TABLE developers_projects;
-DROP SEQUENCE developers_projects_id;
-DROP TABLE customers;
-DROP SEQUENCE customers_id;
-DROP TABLE movies;
-DROP SEQUENCE movies_id;
-DROP TABLE subscribers;
-DROP SEQUENCE subscribers_id;
-DROP TABLE booleantests;
-DROP SEQUENCE booleantests_id;
-DROP TABLE auto_id_tests;
-DROP SEQUENCE auto_id_tests_id;
-DROP TABLE entrants;
-DROP SEQUENCE entrants_id;
-DROP TABLE colnametests;
-DROP SEQUENCE colnametests_id;
-DROP TABLE mixins;
-DROP SEQUENCE mixins_id;
-DROP TABLE people;
-DROP SEQUENCE people_id;
-DROP TABLE binaries;
-DROP SEQUENCE binaries_id;
-DROP TABLE computers;
-DROP SEQUENCE computers_id;
-DROP TABLE tasks;
-DROP SEQUENCE tasks_id;
-EXIT;
@@ -1,3 +0,0 @@
-DROP TABLE courses;
-DROP SEQUENCE courses_id;
-EXIT;
@@ -19,3 +19,5 @@ DROP TABLE tasks;
DROP TABLE posts;
DROP TABLE comments;
DROP TABLE authors;
+DROP TABLE categories;
+DROP TABLE categories_posts;
@@ -155,3 +155,13 @@ CREATE TABLE `tasks` (
`ending` datetime NOT NULL default '0000-00-00 00:00:00',
PRIMARY KEY (`id`)
);
+
+CREATE TABLE `categories` (
+ `id` int(11) NOT NULL auto_increment,
+ `name` VARCHAR(255) NOT NULL
+);
+
+CREATE TABLE `categories_posts` (
+ `category_id` int(11) NOT NULL,
+ `post_id` int(11) NOT NULL
+);
@@ -18,4 +18,6 @@ drop table posts;
drop table comments;
drop table authors;
drop table computers;
+drop table categories;
+drop table categories_posts;
drop sequence rails_sequence;
@@ -192,3 +192,13 @@ create table tasks (
starting date default null,
ending date default null
);
+
+create table categories (
+ id integer not null primary key,
+ name varchar(255) default null
+);
+
+create table categories_posts (
+ category_id integer not null references developers initially deferred disable,
+ post_id int integer not null references developers initially deferred disable
+);
@@ -19,4 +19,6 @@ DROP TABLE posts;
DROP TABLE comments;
DROP TABLE authors;
DROP TABLE tasks;
+DROP TABLE categories;
+DROP TABLE categories_posts;
@@ -173,3 +173,13 @@ CREATE TABLE taske (
ending timestamp,
PRIMARY KEY (id)
);
+
+CREATE TABLE categories (
+ id serial,
+ name varchar(255)
+);
+
+CREATE TABLE categories_posts (
+ category_id integer NOT NULL,
+ post_id int integer NOT NULL
+);
@@ -19,3 +19,5 @@ DROP TABLE tasks;
DROP TABLE posts;
DROP TABLE comments;
DROP TABLE authors;
+DROP TABLE categories;
+DROP TABLE categories_posts;
@@ -142,3 +142,12 @@ CREATE TABLE 'tasks' (
'ending' DATETIME DEFAULT NULL
);
+CREATE TABLE 'categories' (
+ 'id' INTEGER NOT NULL PRIMARY KEY,
+ 'name' VARCHAR(255) NOT NULL
+);
+
+CREATE TABLE 'categories_posts' (
+ 'category_id' INTEGER NOT NULL,
+ 'post_id' INTEGER NOT NULL
+);
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