PostgreSQL, add :if_exists to #drop_schema.

activerecord/CHANGELOG.md

@@ -1,3 +1,9 @@
+*   PostgreSQL, add `:if_exists` option to `#drop_schema`. This makes it
+    possible to drop a schema that might exist without raising an exception if
+    it doesn't.
+
+    *Yves Senn*
+
 *   Only try to nullify has_one target association if the record is persisted.
 
     Fixes #21223.

activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb

@@ -214,8 +214,8 @@ module ActiveRecord
         end
 
         # Drops the schema for the given schema name.
-        def drop_schema schema_name
+        def drop_schema(schema_name, options = {})
-          execute "DROP SCHEMA #{schema_name} CASCADE"
+          execute "DROP SCHEMA#{' IF EXISTS' if options[:if_exists]} #{schema_name} CASCADE"
         end
 
         # Sets the schema search path to a string of comma-separated schema names.

activerecord/test/cases/adapters/postgresql/schema_authorization_test.rb

@@ -31,7 +31,7 @@ class SchemaAuthorizationTest < ActiveRecord::PostgreSQLTestCase
     set_session_auth
     @connection.execute "RESET search_path"
     USERS.each do |u|
-      @connection.execute "DROP SCHEMA #{u} CASCADE"
+      @connection.drop_schema u
       @connection.execute "DROP USER #{u}"
     end
   end

activerecord/test/cases/adapters/postgresql/schema_test.rb

@@ -84,8 +84,8 @@ class SchemaTest < ActiveRecord::PostgreSQLTestCase
   end
 
   teardown do
-    @connection.execute "DROP SCHEMA #{SCHEMA2_NAME} CASCADE"
+    @connection.drop_schema SCHEMA2_NAME, if_exists: true
-    @connection.execute "DROP SCHEMA #{SCHEMA_NAME} CASCADE"
+    @connection.drop_schema SCHEMA_NAME, if_exists: true
   end
 
   def test_schema_names
@@ -121,10 +121,17 @@ class SchemaTest < ActiveRecord::PostgreSQLTestCase
     assert !@connection.schema_names.include?("test_schema3")
   end
 
+  def test_drop_schema_if_exists
+    @connection.create_schema "some_schema"
+    assert_includes @connection.schema_names, "some_schema"
+    @connection.drop_schema "some_schema", if_exists: true
+    assert_not_includes @connection.schema_names, "some_schema"
+  end
+
   def test_habtm_table_name_with_schema
+    ActiveRecord::Base.connection.drop_schema "music", if_exists: true
+    ActiveRecord::Base.connection.create_schema "music"
     ActiveRecord::Base.connection.execute <<-SQL
-      DROP SCHEMA IF EXISTS music CASCADE;
-      CREATE SCHEMA music;
       CREATE TABLE music.albums (id serial primary key);
       CREATE TABLE music.songs (id serial primary key);
       CREATE TABLE music.albums_songs (album_id integer, song_id integer);
@@ -134,12 +141,16 @@ class SchemaTest < ActiveRecord::PostgreSQLTestCase
     Album.create
     assert_equal song, Song.includes(:albums).references(:albums).first
   ensure
-    ActiveRecord::Base.connection.execute "DROP SCHEMA music CASCADE;"
+    ActiveRecord::Base.connection.drop_schema "music", if_exists: true
   end
 
-  def test_raise_drop_schema_with_nonexisting_schema
+  def test_drop_schema_with_nonexisting_schema
     assert_raises(ActiveRecord::StatementInvalid) do
-      @connection.drop_schema "test_schema3"
+      @connection.drop_schema "idontexist"
+    end
+
+    assert_nothing_raised do
+      @connection.drop_schema "idontexist", if_exists: true
     end
   end
 
@@ -462,14 +473,14 @@ class SchemaForeignKeyTest < ActiveRecord::PostgreSQLTestCase
   ensure
     @connection.drop_table "wagons", if_exists: true
     @connection.drop_table "my_schema.trains", if_exists: true
-    @connection.execute "DROP SCHEMA IF EXISTS my_schema"
+    @connection.drop_schema "my_schema", if_exists: true
   end
 end
 
 class DefaultsUsingMultipleSchemasAndDomainTest < ActiveRecord::PostgreSQLTestCase
   setup do
     @connection = ActiveRecord::Base.connection
-    @connection.execute "DROP SCHEMA IF EXISTS schema_1 CASCADE"
+    @connection.drop_schema "schema_1", if_exists: true
     @connection.execute "CREATE SCHEMA schema_1"
     @connection.execute "CREATE DOMAIN schema_1.text AS text"
     @connection.execute "CREATE DOMAIN schema_1.varchar AS varchar"
@@ -487,7 +498,7 @@ class DefaultsUsingMultipleSchemasAndDomainTest < ActiveRecord::PostgreSQLTestCa
 
   teardown do
     @connection.schema_search_path = @old_search_path
-    @connection.execute "DROP SCHEMA IF EXISTS schema_1 CASCADE"
+    @connection.drop_schema "schema_1", if_exists: true
     Default.reset_column_information
   end