Merge pull request #20005 from kamipo/default_expression_support

Add `:expression` option support on the schema default

11 files changed, 100 insertions, 44 deletions

diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index eaeb808144..e14a9a972c 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,13 @@
+*   Add expression support on the schema default.
+
+    Example:
+
+        create_table :posts do |t|
+          t.datetime :published_at, default: -> { 'NOW()' }
+        end
+
+    *Ryuta Kamizono*
+
 *   Fix regression when loading fixture files with symbol keys.
 
     Fixes #22584.
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb b/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb
index bcc41acaa1..7e3760d34b 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb
@@ -102,9 +102,13 @@ module ActiveRecord
         quote_table_name("#{table}.#{attr}")
       end
 
-      def quote_default_expression(value, column) #:nodoc:
-        value = lookup_cast_type(column.sql_type).serialize(value)
-        quote(value)
+      def quote_default_expression(value, column) # :nodoc:
+        if value.is_a?(Proc)
+          value.call
+        else
+          value = lookup_cast_type(column.sql_type).serialize(value)
+          quote(value)
+        end
       end
 
       def quoted_true
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_dumper.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_dumper.rb
index 797662d07c..a95109fdae 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_dumper.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_dumper.rb
@@ -76,11 +76,17 @@ module ActiveRecord
       def schema_default(column)
         type = lookup_cast_type_from_column(column)
         default = type.deserialize(column.default)
-        unless default.nil?
+        if default.nil?
+          schema_expression(column)
+        else
           type.type_cast_for_schema(default)
         end
       end
 
+      def schema_expression(column)
+        "-> { #{column.default_function.inspect} }" if column.default_function
+      end
+
       def schema_collation(column)
         column.collation.inspect if column.collation
       end
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
index d435d91102..3e84786be0 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -495,12 +495,16 @@ module ActiveRecord
       end
 
       # Returns an array of +Column+ objects for the table specified by +table_name+.
-      def columns(table_name)#:nodoc:
+      def columns(table_name) # :nodoc:
         sql = "SHOW FULL FIELDS FROM #{quote_table_name(table_name)}"
         execute_and_free(sql, 'SCHEMA') do |result|
           each_hash(result).map do |field|
             type_metadata = fetch_type_metadata(field[:Type], field[:Extra])
-            new_column(field[:Field], field[:Default], type_metadata, field[:Null] == "YES", nil, field[:Collation])
+            if type_metadata.type == :datetime && field[:Default] == "CURRENT_TIMESTAMP"
+              new_column(field[:Field], nil, type_metadata, field[:Null] == "YES", field[:Default], field[:Collation])
+            else
+              new_column(field[:Field], field[:Default], type_metadata, field[:Null] == "YES", nil, field[:Collation])
+            end
           end
         end
       end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/quoting.rb b/activerecord/lib/active_record/connection_adapters/postgresql/quoting.rb
index d5879ea7df..c1c77a967e 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/quoting.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/quoting.rb
@@ -55,10 +55,11 @@ module ActiveRecord
           end
         end
 
-        # Does not quote function default values for UUID columns
-        def quote_default_expression(value, column) #:nodoc:
-          if column.type == :uuid && value =~ /\(\)/
-            value
+        def quote_default_expression(value, column) # :nodoc:
+          if value.is_a?(Proc)
+            value.call
+          elsif column.type == :uuid && value =~ /\(\)/
+            value # Does not quote function default values for UUID columns
           elsif column.respond_to?(:array?)
             value = type_cast_from_column(column, value)
             quote(value)
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/schema_dumper.rb b/activerecord/lib/active_record/connection_adapters/postgresql/schema_dumper.rb
index a4f0742516..cc7721ddd8 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/schema_dumper.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/schema_dumper.rb
@@ -9,7 +9,7 @@ module ActiveRecord
             spec[:id] = ':bigserial'
           elsif column.type == :uuid
             spec[:id] = ':uuid'
-            spec[:default] = column.default_function.inspect
+            spec[:default] = schema_default(column) || 'nil'
           else
             spec[:id] = column.type.inspect
             spec.merge!(prepare_column_options(column).delete_if { |key, _| [:name, :type, :null].include?(key) })
@@ -41,12 +41,8 @@ module ActiveRecord
           end
         end
 
-        def schema_default(column)
-          if column.default_function
-            column.default_function.inspect unless column.serial?
-          else
-            super
-          end
+        def schema_expression(column)
+          super unless column.serial?
         end
       end
     end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
index 1c20e4700f..2de6fbfaf0 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
@@ -512,8 +512,13 @@ module ActiveRecord
         def extract_value_from_default(default) # :nodoc:
           case default
             # Quoted types
-            when /\A[\(B]?'(.*)'::/m
-              $1.gsub("''".freeze, "'".freeze)
+            when /\A[\(B]?'(.*)'.*::"?([\w. ]+)"?(?:\[\])?\z/m
+              # The default 'now'::date is CURRENT_DATE
+              if $1 == "now".freeze && $2 == "date".freeze
+                nil
+              else
+                $1.gsub("''".freeze, "'".freeze)
+              end
             # Boolean types
             when 'true'.freeze, 'false'.freeze
               default
@@ -535,7 +540,7 @@ module ActiveRecord
         end
 
         def has_default_function?(default_value, default) # :nodoc:
-          !default_value && (%r{\w+\(.*\)} === default)
+          !default_value && (%r{\w+\(.*\)|\(.*\)::\w+} === default)
         end
 
         def load_additional_types(type_map, oids = nil) # :nodoc:
diff --git a/activerecord/test/cases/adapters/postgresql/uuid_test.rb b/activerecord/test/cases/adapters/postgresql/uuid_test.rb
index 3d90790367..7628075ad2 100644
--- a/activerecord/test/cases/adapters/postgresql/uuid_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/uuid_test.rb
@@ -197,14 +197,14 @@ class PostgresqlUUIDGenerationTest < ActiveRecord::PostgreSQLTestCase
 
     def test_schema_dumper_for_uuid_primary_key
       schema = dump_table_schema "pg_uuids"
-      assert_match(/\bcreate_table "pg_uuids", id: :uuid, default: "uuid_generate_v1\(\)"/, schema)
-      assert_match(/t\.uuid   "other_uuid", default: "uuid_generate_v4\(\)"/, schema)
+      assert_match(/\bcreate_table "pg_uuids", id: :uuid, default: -> { "uuid_generate_v1\(\)" }/, schema)
+      assert_match(/t\.uuid   "other_uuid", default: -> { "uuid_generate_v4\(\)" }/, schema)
     end
 
     def test_schema_dumper_for_uuid_primary_key_with_custom_default
       schema = dump_table_schema "pg_uuids_2"
-      assert_match(/\bcreate_table "pg_uuids_2", id: :uuid, default: "my_uuid_generator\(\)"/, schema)
-      assert_match(/t\.uuid   "other_uuid_2", default: "my_uuid_generator\(\)"/, schema)
+      assert_match(/\bcreate_table "pg_uuids_2", id: :uuid, default: -> { "my_uuid_generator\(\)" }/, schema)
+      assert_match(/t\.uuid   "other_uuid_2", default: -> { "my_uuid_generator\(\)" }/, schema)
     end
   end
 end
diff --git a/activerecord/test/cases/defaults_test.rb b/activerecord/test/cases/defaults_test.rb
index fb2d3bd497..69b0487dd8 100644
--- a/activerecord/test/cases/defaults_test.rb
+++ b/activerecord/test/cases/defaults_test.rb
@@ -1,4 +1,5 @@
 require "cases/helper"
+require 'support/schema_dumping_helper'
 require 'models/default'
 require 'models/entrant'
 
@@ -80,7 +81,32 @@ class DefaultStringsTest < ActiveRecord::TestCase
   end
 end
 
+if current_adapter?(:PostgreSQLAdapter)
+  class PostgresqlDefaultExpressionTest < ActiveRecord::TestCase
+    include SchemaDumpingHelper
+
+    test "schema dump includes default expression" do
+      output = dump_table_schema("defaults")
+      assert_match %r/t\.date\s+"modified_date",\s+default: -> { "\('now'::text\)::date" }/, output
+      assert_match %r/t\.date\s+"modified_date_function",\s+default: -> { "now\(\)" }/, output
+      assert_match %r/t\.datetime\s+"modified_time",\s+default: -> { "now\(\)" }/, output
+      assert_match %r/t\.datetime\s+"modified_time_function",\s+default: -> { "now\(\)" }/, output
+    end
+  end
+end
+
 if current_adapter?(:Mysql2Adapter)
+  class MysqlDefaultExpressionTest < ActiveRecord::TestCase
+    include SchemaDumpingHelper
+
+    if ActiveRecord::Base.connection.version >= '5.6.0'
+      test "schema dump includes default expression" do
+        output = dump_table_schema("datetime_defaults")
+        assert_match %r/t\.datetime\s+"modified_datetime",\s+default: -> { "CURRENT_TIMESTAMP" }/, output
+      end
+    end
+  end
+
   class DefaultsTestWithoutTransactionalFixtures < ActiveRecord::TestCase
     # ActiveRecord::Base#create! (and #save and other related methods) will
     # open a new transaction. When in transactional tests mode, this will
diff --git a/activerecord/test/schema/mysql2_specific_schema.rb b/activerecord/test/schema/mysql2_specific_schema.rb
index 752572a79c..701e6f45b3 100644
--- a/activerecord/test/schema/mysql2_specific_schema.rb
+++ b/activerecord/test/schema/mysql2_specific_schema.rb
@@ -1,4 +1,11 @@
 ActiveRecord::Schema.define do
+
+  if ActiveRecord::Base.connection.version >= '5.6.0'
+    create_table :datetime_defaults, force: true do |t|
+      t.datetime :modified_datetime, default: -> { 'CURRENT_TIMESTAMP' }
+    end
+  end
+
   create_table :binary_fields, force: true do |t|
     t.binary :var_binary, limit: 255
     t.binary :var_binary_large, limit: 4095
diff --git a/activerecord/test/schema/postgresql_specific_schema.rb b/activerecord/test/schema/postgresql_specific_schema.rb
index df0362573b..3a5d73a0ed 100644
--- a/activerecord/test/schema/postgresql_specific_schema.rb
+++ b/activerecord/test/schema/postgresql_specific_schema.rb
@@ -11,7 +11,23 @@ ActiveRecord::Schema.define do
     t.uuid :uuid_parent_id
   end
 
-  %w(postgresql_times postgresql_oids defaults postgresql_timestamp_with_zones
+  create_table :defaults, force: true do |t|
+    t.date :modified_date, default: -> { 'CURRENT_DATE' }
+    t.date :modified_date_function, default: -> { 'now()' }
+    t.date :fixed_date, default: '2004-01-01'
+    t.datetime :modified_time, default: -> { 'CURRENT_TIMESTAMP' }
+    t.datetime :modified_time_function, default: -> { 'now()' }
+    t.datetime :fixed_time, default: '2004-01-01 00:00:00.000000-00'
+    t.column :char1, 'char(1)', default: 'Y'
+    t.string :char2, limit: 50, default: 'a varchar field'
+    t.text :char3, default: 'a text field'
+    t.bigint :bigint_default, default: -> { '0::bigint' }
+    t.text :multiline_default, default: '--- []
+
+'
+  end
+
+  %w(postgresql_times postgresql_oids postgresql_timestamp_with_zones
       postgresql_partitioned_table postgresql_partitioned_table_parent).each do |table_name|
     drop_table table_name, if_exists: true
   end
@@ -28,25 +44,6 @@ ActiveRecord::Schema.define do
   end
 
   execute <<_SQL
-    CREATE TABLE defaults (
-    id serial primary key,
-    modified_date date default CURRENT_DATE,
-    modified_date_function date default now(),
-    fixed_date date default '2004-01-01',
-    modified_time timestamp default CURRENT_TIMESTAMP,
-    modified_time_function timestamp default now(),
-    fixed_time timestamp default '2004-01-01 00:00:00.000000-00',
-    char1 char(1) default 'Y',
-    char2 character varying(50) default 'a varchar field',
-    char3 text default 'a text field',
-    bigint_default bigint default 0::bigint,
-    multiline_default text DEFAULT '--- []
-
-'::text
-);
-_SQL
-
-  execute <<_SQL
   CREATE TABLE postgresql_times (
     id SERIAL PRIMARY KEY,
     time_interval INTERVAL,