Merge branch 'master' into laurocaetano-fix_send_file

* master: (536 commits)
  doc, API example on how to use `Model#exists?` with multiple IDs. [ci skip]
  Restore DATABASE_URL even if it's nil in connection_handler test
  [ci skip] - error_messages_for has been deprecated since 2.3.8 - lets reduce any confusion for users
  Ensure Active Record connection consistency
  Revert "ask the fixture set for the sql statements"
  Check `respond_to` before delegation due to: https://github.com/ruby/ruby/commit/d781caaf313b8649948c107bba277e5ad7307314
  Adding Hash#compact and Hash#compact! methods
  MySQL version 4.1 was EOL on December 31, 2009 We should at least recommend modern versions of MySQL to users.
  clear cache on body close so that cache remains during rendering
  add a more restricted codepath for templates fixes #13390
  refactor generator tests to use block form of Tempfile
  Fix typo [ci skip]
  Move finish_template as the last public method in the generator
  Minor typos fix [ci skip]
  make `change_column_null` reversible. Closes #13576.
  create/drop test and development databases only if RAILS_ENV is nil
  Revert "Speedup String#to"
  typo fix in test name. [ci skip].
  `core_ext/string/access.rb` test what we are documenting.
  Fix typo in image_tag documentation
  ...

Conflicts:
	actionpack/CHANGELOG.md

5 files changed, 74 insertions, 44 deletions

diff --git a/activerecord/lib/active_record/relation/calculations.rb b/activerecord/lib/active_record/relation/calculations.rb
index 2d267183ce..45ffb99868 100644
--- a/activerecord/lib/active_record/relation/calculations.rb
+++ b/activerecord/lib/active_record/relation/calculations.rb
@@ -19,16 +19,21 @@ module ActiveRecord
     #
     #   Person.group(:city).count
     #   # => { 'Rome' => 5, 'Paris' => 3 }
-    def count(column_name = nil)
-      calculate(:count, column_name)
+    def count(column_name = nil, options = {})
+      # TODO: Remove options argument as soon we remove support to
+      # activerecord-deprecated_finders.
+      column_name, options = nil, column_name if column_name.is_a?(Hash)
+      calculate(:count, column_name, options)
     end
 
     # Calculates the average value on a given column. Returns +nil+ if there's
     # no row. See +calculate+ for examples with options.
     #
     #   Person.average(:age) # => 35.8
-    def average(column_name)
-      calculate(:average, column_name)
+    def average(column_name, options = {})
+      # TODO: Remove options argument as soon we remove support to
+      # activerecord-deprecated_finders.
+      calculate(:average, column_name, options)
     end
 
     # Calculates the minimum value on a given column. The value is returned
@@ -36,8 +41,10 @@ module ActiveRecord
     # +calculate+ for examples with options.
     #
     #   Person.minimum(:age) # => 7
-    def minimum(column_name)
-      calculate(:minimum, column_name)
+    def minimum(column_name, options = {})
+      # TODO: Remove options argument as soon we remove support to
+      # activerecord-deprecated_finders.
+      calculate(:minimum, column_name, options)
     end
 
     # Calculates the maximum value on a given column. The value is returned
@@ -45,8 +52,10 @@ module ActiveRecord
     # +calculate+ for examples with options.
     #
     #   Person.maximum(:age) # => 93
-    def maximum(column_name)
-      calculate(:maximum, column_name)
+    def maximum(column_name, options = {})
+      # TODO: Remove options argument as soon we remove support to
+      # activerecord-deprecated_finders.
+      calculate(:maximum, column_name, options)
     end
 
     # Calculates the sum of values on a given column. The value is returned
@@ -89,15 +98,17 @@ module ActiveRecord
     #   Person.group(:last_name).having("min(age) > 17").minimum(:age)
     #
     #   Person.sum("2 * age")
-    def calculate(operation, column_name)
+    def calculate(operation, column_name, options = {})
+      # TODO: Remove options argument as soon we remove support to
+      # activerecord-deprecated_finders.
       if column_name.is_a?(Symbol) && attribute_alias?(column_name)
         column_name = attribute_alias(column_name)
       end
 
       if has_include?(column_name)
-        construct_relation_for_association_calculations.calculate(operation, column_name)
+        construct_relation_for_association_calculations.calculate(operation, column_name, options)
       else
-        perform_calculation(operation, column_name)
+        perform_calculation(operation, column_name, options)
       end
     end
 
@@ -180,7 +191,9 @@ module ActiveRecord
       eager_loading? || (includes_values.present? && (column_name || references_eager_loaded_tables?))
     end
 
-    def perform_calculation(operation, column_name)
+    def perform_calculation(operation, column_name, options = {})
+      # TODO: Remove options argument as soon we remove support to
+      # activerecord-deprecated_finders.
       operation = operation.to_s.downcase
 
       # If #count is used with #distinct / #uniq it is considered distinct. (eg. relation.distinct.count)
@@ -311,7 +324,9 @@ module ActiveRecord
         }
         key = key.first if key.size == 1
         key = key_records[key] if associated
-        [key, type_cast_calculated_value(row[aggregate_alias], column_for(column_name), operation)]
+
+        column_type = calculated_data.column_types.fetch(aggregate_alias) { column_for(column_name) }
+        [key, type_cast_calculated_value(row[aggregate_alias], column_type, operation)]
       end]
     end
 
diff --git a/activerecord/lib/active_record/relation/delegation.rb b/activerecord/lib/active_record/relation/delegation.rb
index 1e15bddcdf..21beed332f 100644
--- a/activerecord/lib/active_record/relation/delegation.rb
+++ b/activerecord/lib/active_record/relation/delegation.rb
@@ -1,3 +1,4 @@
+require 'set'
 require 'active_support/concern'
 require 'active_support/deprecation'
 
@@ -36,7 +37,14 @@ module ActiveRecord
     # may vary depending on the klass of a relation, so we create a subclass of Relation
     # for each different klass, and the delegations are compiled into that subclass only.
 
-    delegate :to_xml, :to_yaml, :length, :collect, :map, :each, :all?, :include?, :to_ary, :to => :to_a
+    BLACKLISTED_ARRAY_METHODS = [
+      :compact!, :flatten!, :reject!, :reverse!, :rotate!, :map!,
+      :shuffle!, :slice!, :sort!, :sort_by!, :delete_if,
+      :keep_if, :pop, :shift, :delete_at, :compact
+    ].to_set # :nodoc:
+
+    delegate :to_xml, :to_yaml, :length, :collect, :map, :each, :all?, :include?, :to_ary, to: :to_a
+
     delegate :table_name, :quoted_table_name, :primary_key, :quoted_primary_key,
              :connection, :columns_hash, :to => :klass
 
@@ -64,7 +72,7 @@ module ActiveRecord
               RUBY
             else
               define_method method do |*args, &block|
-                scoping { @klass.send(method, *args, &block) }
+                scoping { @klass.public_send(method, *args, &block) }
               end
             end
           end
@@ -83,13 +91,10 @@ module ActiveRecord
       def method_missing(method, *args, &block)
         if @klass.respond_to?(method)
           self.class.delegate_to_scoped_klass(method)
-          scoping { @klass.send(method, *args, &block) }
-        elsif array_delegable?(method)
-          self.class.delegate method, :to => :to_a
-          to_a.send(method, *args, &block)
+          scoping { @klass.public_send(method, *args, &block) }
         elsif arel.respond_to?(method)
           self.class.delegate method, :to => :arel
-          arel.send(method, *args, &block)
+          arel.public_send(method, *args, &block)
         else
           super
         end
@@ -109,30 +114,24 @@ module ActiveRecord
     end
 
     def respond_to?(method, include_private = false)
-      super || array_delegable?(method) ||
-        @klass.respond_to?(method, include_private) ||
+      super || @klass.respond_to?(method, include_private) ||
+        array_delegable?(method) ||
         arel.respond_to?(method, include_private)
     end
 
     protected
 
     def array_delegable?(method)
-      defined = Array.method_defined?(method)
-      if defined && method.to_s.ends_with?('!')
-        ActiveSupport::Deprecation.warn(
-          "Association will no longer delegate #{method} to #to_a as of Rails 4.2. You instead must first call #to_a on the association to expose the array to be acted on."
-        )
-      end
-      defined
+      Array.method_defined?(method) && BLACKLISTED_ARRAY_METHODS.exclude?(method)
     end
 
     def method_missing(method, *args, &block)
       if @klass.respond_to?(method)
-        scoping { @klass.send(method, *args, &block) }
+        scoping { @klass.public_send(method, *args, &block) }
       elsif array_delegable?(method)
-        to_a.send(method, *args, &block)
+        to_a.public_send(method, *args, &block)
       elsif arel.respond_to?(method)
-        arel.send(method, *args, &block)
+        arel.public_send(method, *args, &block)
       else
         super
       end
diff --git a/activerecord/lib/active_record/relation/finder_methods.rb b/activerecord/lib/active_record/relation/finder_methods.rb
index d91d6367a3..4984dbd277 100644
--- a/activerecord/lib/active_record/relation/finder_methods.rb
+++ b/activerecord/lib/active_record/relation/finder_methods.rb
@@ -195,6 +195,7 @@ module ActiveRecord
     #   Person.exists?(5)
     #   Person.exists?('5')
     #   Person.exists?(['name LIKE ?', "%#{query}%"])
+    #   Person.exists?(id: [1, 4, 8])
     #   Person.exists?(name: 'David')
     #   Person.exists?(false)
     #   Person.exists?
@@ -384,7 +385,7 @@ module ActiveRecord
         @records.last
       else
         @last ||=
-          if offset_value || limit_value
+          if limit_value
             to_a.last
           else
             reverse_order.limit(1).to_a.first
diff --git a/activerecord/lib/active_record/relation/predicate_builder.rb b/activerecord/lib/active_record/relation/predicate_builder.rb
index c60cd27a83..1252af7635 100644
--- a/activerecord/lib/active_record/relation/predicate_builder.rb
+++ b/activerecord/lib/active_record/relation/predicate_builder.rb
@@ -55,9 +55,9 @@ module ActiveRecord
       #
       # For polymorphic relationships, find the foreign key and type:
       # PriceEstimate.where(estimate_of: treasure)
-      if klass && value.is_a?(Base) && reflection = klass.reflect_on_association(column.to_sym)
-        if reflection.polymorphic?
-          queries << build(table[reflection.foreign_type], value.class.base_class)
+      if klass && reflection = klass.reflect_on_association(column.to_sym)
+        if reflection.polymorphic? && base_class = polymorphic_base_class_from_value(value)
+          queries << build(table[reflection.foreign_type], base_class)
         end
 
         column = reflection.foreign_key
@@ -67,6 +67,18 @@ module ActiveRecord
       queries
     end
 
+    def self.polymorphic_base_class_from_value(value)
+      case value
+      when Relation
+        value.klass.base_class
+      when Array
+        val = value.compact.first
+        val.class.base_class if val.is_a?(Base)
+      when Base
+        value.class.base_class
+      end
+    end
+
     def self.references(attributes)
       attributes.map do |key, value|
         if value.is_a?(Hash)
diff --git a/activerecord/lib/active_record/relation/query_methods.rb b/activerecord/lib/active_record/relation/query_methods.rb
index cacc787eba..78da6a83ec 100644
--- a/activerecord/lib/active_record/relation/query_methods.rb
+++ b/activerecord/lib/active_record/relation/query_methods.rb
@@ -37,6 +37,8 @@ module ActiveRecord
       def not(opts, *rest)
         where_value = @scope.send(:build_where, opts, rest).map do |rel|
           case rel
+          when NilClass
+            raise ArgumentError, 'Invalid argument for .where.not(), got nil.'
           when Arel::Nodes::In
             Arel::Nodes::NotIn.new(rel.left, rel.right)
           when Arel::Nodes::Equality
@@ -427,7 +429,7 @@ module ActiveRecord
     # === string
     #
     # A single string, without additional arguments, is passed to the query
-    # constructor as a SQL fragment, and used in the where clause of the query.
+    # constructor as an SQL fragment, and used in the where clause of the query.
     #
     #    Client.where("orders_count = '2'")
     #    # SELECT * from clients where orders_count = '2';
@@ -631,12 +633,11 @@ module ActiveRecord
       self
     end
 
-    # Returns a chainable relation with zero records, specifically an
-    # instance of the <tt>ActiveRecord::NullRelation</tt> class.
+    # Returns a chainable relation with zero records.
     #
-    # The returned <tt>ActiveRecord::NullRelation</tt> inherits from Relation and implements the
-    # Null Object pattern. It is an object with defined null behavior and always returns an empty
-    # array of records without querying the database.
+    # The returned relation implements the Null Object pattern. It is an
+    # object with defined null behavior and always returns an empty array of
+    # records without querying the database.
     #
     # Any subsequent condition chained to the returned relation will continue
     # generating an empty relation and will not fire any query to the database.
@@ -656,7 +657,7 @@ module ActiveRecord
     #     when 'Reviewer'
     #       Post.published
     #     when 'Bad User'
-    #       Post.none # => returning [] instead breaks the previous code
+    #       Post.none # It can't be chained if [] is returned.
     #     end
     #   end
     #
@@ -983,8 +984,10 @@ module ActiveRecord
     end
 
     def build_select(arel, selects)
-      unless selects.empty?
+      if !selects.empty?
         arel.project(*selects)
+      elsif from_value
+        arel.project(Arel.star)
       else
         arel.project(@klass.arel_table[Arel.star])
       end