Use connection-specific bytea escaping

In our normal usage, it's rare for this to make a difference... but is
more technically correct.

As well as a spec that proves this is a good idea, let's also add a more
sane-looking one that just covers basic to_sql functionality. There
aren't many places where we actually use escape_bytea, but that's one
that won't be going away.

2 files changed, 19 insertions, 2 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/quoting.rb b/activerecord/lib/active_record/connection_adapters/postgresql/quoting.rb
index 210172cf32..ac3b0f713d 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/quoting.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/quoting.rb
@@ -4,14 +4,14 @@ module ActiveRecord
       module Quoting
         # Escapes binary strings for bytea input to the database.
         def escape_bytea(value)
-          PGconn.escape_bytea(value) if value
+          @connection.escape_bytea(value) if value
         end
 
         # Unescapes bytea output from a database to the binary string it represents.
         # NOTE: This is NOT an inverse of escape_bytea! This is only to be used
         # on escaped binary output from database drive.
         def unescape_bytea(value)
-          PGconn.unescape_bytea(value) if value
+          @connection.unescape_bytea(value) if value
         end
 
         # Quotes PostgreSQL-specific data types for SQL input.
diff --git a/activerecord/test/cases/adapters/postgresql/bytea_test.rb b/activerecord/test/cases/adapters/postgresql/bytea_test.rb
index c3394d7712..84fa199f17 100644
--- a/activerecord/test/cases/adapters/postgresql/bytea_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/bytea_test.rb
@@ -70,6 +70,23 @@ class PostgresqlByteaTest < ActiveRecord::TestCase
     assert_equal(data, record.payload)
   end
 
+  def test_via_to_sql
+    data = "'\u001F\\"
+    record = ByteaDataType.create(payload: data)
+    sql = ByteaDataType.where(payload: data).select(:payload).to_sql
+    result = @connection.query(sql)
+    assert_equal([[data]], result)
+  end
+
+  def test_via_to_sql_with_complicating_connection
+    Thread.new do
+      other_conn = ActiveRecord::Base.connection
+      other_conn.execute('SET standard_conforming_strings = off')
+    end.join
+
+    test_via_to_sql
+  end
+
   def test_write_binary
     data = File.read(File.join(File.dirname(__FILE__), '..', '..', '..', 'assets', 'example.log'))
     assert(data.size > 1)