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Merge pull request #6058 from RStankov/relation-from-to-accept-other-…

…relation-objects

Relation#from to accept other Relation objects
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2 parents 03f8a57 + 64872d1 commit 77a40722f74a30b5b3d028a3d20129a2aad8722a @jonleighton jonleighton committed May 17, 2012
@@ -1,5 +1,12 @@
## Rails 4.0.0 (unreleased) ##
+* Added ability to ActiveRecord::Relation#from to accept other ActiveRecord::Relation objects
+
+ Record.from(subquery)
+ Record.from(subquery, :a)
+
+ *Radoslav Stankov*
+
* Added custom coders support for ActiveRecord::Store. Now you can set
your custom coder like this:
@@ -43,7 +43,7 @@ def initialize(relation, other)
def normal_values
Relation::SINGLE_VALUE_METHODS +
Relation::MULTI_VALUE_METHODS -
- [:where, :order, :bind, :reverse_order, :lock, :create_with, :reordering]
+ [:where, :order, :bind, :reverse_order, :lock, :create_with, :reordering, :from]
end
def merge
@@ -76,6 +76,7 @@ def merge_multi_values
end
def merge_single_values
+ relation.from_value = values[:from] unless relation.from_value
relation.lock_value = values[:lock] unless relation.lock_value
relation.reverse_order_value = values[:reverse_order]
@@ -300,12 +300,25 @@ def create_with!(value)
self
end
- def from(value)
- spawn.from!(value)
+ # Specifies table from which the records will be fetched. For example:
+ #
+ # Topic.select('title').from('posts')
+ # #=> SELECT title FROM posts
+ #
+ # Can accept other relation objects. For example:
+ #
+ # Topic.select('title').from(Topics.approved)
+ # # => SELECT title FROM (SELECT * FROM topics WHERE approved = 't') subquery
+ #
+ # Topics.select('a.title').from(Topics.approved, :a)
+ # # => SELECT a.title FROM (SELECT * FROM topics WHERE approved = 't') a
+ #
+ def from(value, subquery_name = nil)
+ spawn.from!(value, subquery_name)
end
- def from!(value)
- self.from_value = value
+ def from!(value, subquery_name = nil)
+ self.from_value = [value, subquery_name]
self
end
@@ -415,7 +428,7 @@ def build_arel
build_select(arel, select_values.uniq)
arel.distinct(uniq_value)
- arel.from(from_value) if from_value
+ arel.from(build_from) if from_value
arel.lock(lock_value) if lock_value
arel
@@ -464,6 +477,17 @@ def build_where(opts, other = [])
end
end
+ def build_from
+ opts, name = from_value
+ case opts
+ when Relation
+ name ||= 'subquery'
+ opts.arel.as(name.to_s)
+ else
+ opts
+ end
+ end
+
def build_joins(manager, joins)
buckets = joins.group_by do |join|
case join
@@ -203,13 +203,18 @@ def relation
assert_equal [], relation.extending_values
end
- (Relation::SINGLE_VALUE_METHODS - [:lock, :reordering, :reverse_order, :create_with]).each do |method|
+ (Relation::SINGLE_VALUE_METHODS - [:from, :lock, :reordering, :reverse_order, :create_with]).each do |method|
test "##{method}!" do
assert relation.public_send("#{method}!", :foo).equal?(relation)
assert_equal :foo, relation.public_send("#{method}_value")
end
end
+ test '#from!' do
+ assert relation.from!('foo').equal?(relation)
+ assert_equal ['foo', nil], relation.from_value
+ end
+
test '#lock!' do
assert relation.lock!('foo').equal?(relation)
assert_equal 'foo', relation.lock_value
@@ -133,6 +133,13 @@ def test_reload
assert topics.loaded?
end
+ def test_finiding_with_subquery
+ relation = Topic.where(:approved => true)
+ assert_equal relation.to_a, Topic.select('*').from(relation).to_a
+ assert_equal relation.to_a, Topic.select('subquery.*').from(relation).to_a
+ assert_equal relation.to_a, Topic.select('a.*').from(relation, :a).to_a
+ end
+
def test_finding_with_conditions
assert_equal ["David"], Author.where(:name => 'David').map(&:name)
assert_equal ['Mary'], Author.where(["name = ?", 'Mary']).map(&:name)

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