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let AR::FinderMethods#exists? return singletons in all cases [closes #…

…11592]

This fixes a regression. The documentation said in its introduction
paragraph that the method returns trythy/falsy, but then below it
was said that if there were no arguments you'd get `true` or `false`.
Also when the argument is exactly `false` a singleton is documented
to be returned.

The method was not returning the singletons so it didn't conform to
those special cases.

The best solution here seems to be to just return singletons in all
cases. This solution is backwards compatible. Also, the contract
has been revised because it has no sense that the predicate varies
that way depending on the input. I bet the previous contract was just
an accident, not something mixed on purpose.
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1 parent 563634f commit 1af0c17f2b397337b927fdec3b97efa5502d988c @fxn fxn committed
Showing with 35 additions and 33 deletions.
  1. +7 −7 activerecord/lib/active_record/relation/finder_methods.rb
  2. +28 −26 activerecord/test/cases/finder_test.rb
View
14 activerecord/lib/active_record/relation/finder_methods.rb
@@ -130,21 +130,21 @@ def last!
last or raise RecordNotFound
end
- # Returns truthy if a record exists in the table that matches the +id+ or
- # conditions given, or falsy otherwise. The argument can take six forms:
+ # Returns +true+ if a record exists in the table that matches the +id+ or
+ # conditions given, or +false+ otherwise. The argument can take six forms:
#
# * Integer - Finds the record with this primary key.
# * String - Finds the record with a primary key corresponding to this
# string (such as <tt>'5'</tt>).
# * Array - Finds the record that matches these +find+-style conditions
- # (such as <tt>['color = ?', 'red']</tt>).
+ # (such as <tt>['name LIKE ?', "%#{query}%"]</tt>).
# * Hash - Finds the record that matches these +find+-style conditions
- # (such as <tt>{color: 'red'}</tt>).
+ # (such as <tt>{name: 'David'}</tt>).
# * +false+ - Returns always +false+.
# * No args - Returns +false+ if the table is empty, +true+ otherwise.
#
- # For more information about specifying conditions as a Hash or Array,
- # see the Conditions section in the introduction to ActiveRecord::Base.
+ # For more information about specifying conditions as a hash or array,
+ # see the Conditions section in the introduction to <tt>ActiveRecord::Base</tt>.
#
# Note: You can't pass in a condition as a string (like <tt>name =
# 'Jamie'</tt>), since it would be sanitized and then queried against
@@ -171,7 +171,7 @@ def exists?(conditions = :none)
relation = relation.where(table[primary_key].eq(conditions)) if conditions != :none
end
- connection.select_value(relation, "#{name} Exists", relation.bind_values)
+ connection.select_value(relation, "#{name} Exists", relation.bind_values) ? true : false
rescue ThrowResult
false
end
View
54 activerecord/test/cases/finder_test.rb
@@ -45,16 +45,17 @@ def test_find_with_string
end
def test_exists
- assert Topic.exists?(1)
- assert Topic.exists?("1")
- assert Topic.exists?(:author_name => "David")
- assert Topic.exists?(:author_name => "Mary", :approved => true)
- assert Topic.exists?(["parent_id = ?", 1])
- assert !Topic.exists?(45)
- assert !Topic.exists?(Topic.new)
+ assert_equal true, Topic.exists?(1)
+ assert_equal true, Topic.exists?("1")
+ assert_equal true, Topic.exists?(author_name: "David")
+ assert_equal true, Topic.exists?(author_name: "Mary", approved: true)
+ assert_equal true, Topic.exists?(["parent_id = ?", 1])
+
+ assert_equal false, Topic.exists?(45)
+ assert_equal false, Topic.exists?(Topic.new)
begin
- assert !Topic.exists?("foo")
+ assert_equal false, Topic.exists?("foo")
rescue ActiveRecord::StatementInvalid
# PostgreSQL complains about string comparison with integer field
rescue Exception
@@ -71,61 +72,62 @@ def test_exists_does_not_select_columns_without_alias
end
def test_exists_returns_true_with_one_record_and_no_args
- assert Topic.exists?
+ assert_equal true, Topic.exists?
end
def test_exists_returns_false_with_false_arg
- assert !Topic.exists?(false)
+ assert_equal false, Topic.exists?(false)
end
# exists? should handle nil for id's that come from URLs and always return false
# (example: Topic.exists?(params[:id])) where params[:id] is nil
def test_exists_with_nil_arg
- assert !Topic.exists?(nil)
- assert Topic.exists?
- assert !Topic.first.replies.exists?(nil)
- assert Topic.first.replies.exists?
+ assert_equal false, Topic.exists?(nil)
+ assert_equal true, Topic.exists?
+
+ assert_equal false, Topic.first.replies.exists?(nil)
+ assert_equal true, Topic.first.replies.exists?
end
# ensures +exists?+ runs valid SQL by excluding order value
def test_exists_with_order
- assert Topic.order(:id).distinct.exists?
+ assert_equal true, Topic.order(:id).distinct.exists?
end
def test_exists_with_includes_limit_and_empty_result
- assert !Topic.includes(:replies).limit(0).exists?
- assert !Topic.includes(:replies).limit(1).where('0 = 1').exists?
+ assert_equal false, Topic.includes(:replies).limit(0).exists?
+ assert_equal false, Topic.includes(:replies).limit(1).where('0 = 1').exists?
end
def test_exists_with_distinct_association_includes_and_limit
author = Author.first
- assert !author.unique_categorized_posts.includes(:special_comments).limit(0).exists?
- assert author.unique_categorized_posts.includes(:special_comments).limit(1).exists?
+ assert_equal false, author.unique_categorized_posts.includes(:special_comments).limit(0).exists?
+ assert_equal true, author.unique_categorized_posts.includes(:special_comments).limit(1).exists?
end
def test_exists_with_distinct_association_includes_limit_and_order
author = Author.first
- assert !author.unique_categorized_posts.includes(:special_comments).order('comments.taggings_count DESC').limit(0).exists?
- assert author.unique_categorized_posts.includes(:special_comments).order('comments.taggings_count DESC').limit(1).exists?
+ assert_equal false, author.unique_categorized_posts.includes(:special_comments).order('comments.taggings_count DESC').limit(0).exists?
+ assert_equal true, author.unique_categorized_posts.includes(:special_comments).order('comments.taggings_count DESC').limit(1).exists?
end
def test_exists_with_empty_table_and_no_args_given
Topic.delete_all
- assert !Topic.exists?
+ assert_equal false, Topic.exists?
end
def test_exists_with_aggregate_having_three_mappings
existing_address = customers(:david).address
- assert Customer.exists?(:address => existing_address)
+ assert_equal true, Customer.exists?(:address => existing_address)
end
def test_exists_with_aggregate_having_three_mappings_with_one_difference
existing_address = customers(:david).address
- assert !Customer.exists?(:address =>
+ assert_equal false, Customer.exists?(:address =>
Address.new(existing_address.street, existing_address.city, existing_address.country + "1"))
- assert !Customer.exists?(:address =>
+ assert_equal false, Customer.exists?(:address =>
Address.new(existing_address.street, existing_address.city + "1", existing_address.country))
- assert !Customer.exists?(:address =>
+ assert_equal false, Customer.exists?(:address =>
Address.new(existing_address.street + "1", existing_address.city, existing_address.country))
end

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