Add sqlMessage property to Error objects

closes mysqljs#1714

Changes.md

@@ -7,6 +7,7 @@ you spot any mistakes.
 ## HEAD
 
 * Add `sql` property to query `Error` objects #1462 #1628 #1629
+* Add `sqlMessage` property to `Error` objects #1714
 * Update `bignumber.js` to 4.0.2
 * Update `readable-stream` to 2.2.9
 * Use `safe-buffer` for improved Buffer API

Readme.md

@@ -1117,6 +1117,8 @@ object. Additionally they typically come with two extra properties:
 * `err.sql`: String, contains the full SQL of the failed query. This can be
   useful when using a higher level interface like an ORM that is generating
   the queries.
+* `err.sqlMessage`: String, contains the message string that provides a
+  textual description of the error. Only populated from [MySQL server error][].
 
 [Error]: https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Error
 [MySQL server error]: http://dev.mysql.com/doc/refman/5.5/en/error-messages-server.html

lib/protocol/sequences/Sequence.js

@@ -52,7 +52,9 @@ Sequence.prototype._packetToError = function(packet) {
   var err  = new Error(code + ': ' + packet.message);
   err.code = code;
   err.errno = packet.errno;
-  err.sqlState = packet.sqlState;
+
+  err.sqlMessage = packet.message;
+  err.sqlState   = packet.sqlState;
 
   return err;
 };

test/integration/connection/test-error-sqlmessage.js

@@ -0,0 +1,59 @@
+var assert = require('assert');
+var common = require('../../common');
+
+var table = 'error_message_test';
+var message = 'Name must not contain b.';
+
+common.getTestConnection(function (err, connection) {
+  assert.ifError(err);
+
+  common.useTestDb(connection);
+
+  createTestTable(function (err3) {
+    assert.ifError(err3);
+
+    // Violates trigger condition, so it will throw an error on insert
+    connection.query('INSERT INTO ?? (name) VALUES ?', [table, [['bbbbbbbbbb']]], function (err4) {
+      // Remove table when insert finishes
+      connection.query('DROP TABLE IF EXISTS ??', [table], function (err5) {
+        assert.ifError(err5);
+        assert.ok(err4);
+        assert.equal(err4.sqlMessage, message, 'error sqlMessage property is the trigger error message');
+        connection.end(assert.ifError);
+      });
+    });
+  });
+
+  function createTestTable(cb) {
+    // Must use real table because temporary tables cannot have triggers
+    connection.query([
+      'CREATE TABLE ?? (',
+      '`name` varchar(255)',
+      ') ENGINE=InnoDB DEFAULT CHARSET=utf8'
+    ].join('\n'), [table], function (err1) {
+      if (err1) {
+        cb(err1);
+      } else {
+        // Create a trigger that throws error when name contains the letter "b"
+        connection.query([
+          'CREATE TRIGGER `validateName`',
+          'BEFORE INSERT ON ??',
+          'FOR EACH ROW BEGIN',
+          'IF (NEW.name like \'%b%\') THEN',
+          'SIGNAL SQLSTATE \'45000\' SET MESSAGE_TEXT = ?;',
+          'END IF;',
+          'END;'
+        ].join('\n'), [table, message], function (err2) {
+          if (!err2) {
+            cb();
+          } else {
+            // Clean up table if create trigger fails
+            connection.query('DROP TABLE IF EXISTS ??', [table], function () {
+              cb(err2);
+            });
+          }
+        });
+      }
+    });
+  }
+});