Fix prepared statement with function has wrong parameter encoding (#84)

Author: gvachkov

lib/protocol/Writer.js

@@ -427,41 +427,20 @@ Writer.prototype[TypeCode.DECIMAL] = function writeDecimal(value) {
 };
 
 Writer.prototype[TypeCode.NSTRING] = function writeNString(value) {
-  if (this._useCesu8) {
-    var encoded = util.convert.encode(value, true);
-    this.push(createBinaryOutBuffer(TypeCode.NSTRING, encoded));
-  } else {
-    this.writeCharacters(value, 'utf8');
-  }
+  this.writeCharacters(TypeCode.NSTRING, value);
 };
 
 Writer.prototype[TypeCode.STRING] = function writeString(value) {
-  this.writeCharacters(value, 'ascii');
+  this.writeCharacters(TypeCode.STRING, value);
 };
 
-Writer.prototype.writeCharacters = function writeCharacters(value, encoding) {
-  var type = encoding === 'ascii' ? TypeCode.STRING : TypeCode.NSTRING;
-  var length = Buffer.byteLength(value, encoding);
-  var buffer;
-  if (length <= 245) {
-    buffer = new Buffer(2 + length);
-    buffer[0] = type;
-    buffer[1] = length;
-    buffer.write(value, 2, length, encoding);
-  } else if (length <= 32767) {
-    buffer = new Buffer(4 + length);
-    buffer[0] = type;
-    buffer[1] = 246;
-    buffer.writeInt16LE(length, 2);
-    buffer.write(value, 4, length, encoding);
-  } else {
-    buffer = new Buffer(6 + length);
-    buffer[0] = type;
-    buffer[1] = 247;
-    buffer.writeInt32LE(length, 2);
-    buffer.write(value, 6, length, encoding);
+Writer.prototype.writeCharacters = function writeCharacters(type, value) {
+  if (typeof value !== 'string') {
+    throw new TypeError('Argument must be a string');
   }
-  this.push(buffer);
+
+  var encoded = util.convert.encode(value, this._useCesu8);
+  this.push(createBinaryOutBuffer(type, encoded));
 };
 
 Writer.prototype[TypeCode.BINARY] = function writeBinary(value) {

test/lib.Writer.js

@@ -209,6 +209,13 @@ describe('Lib', function () {
       writer.setValues([value]);
       writer.length.should.equal(length + 6);
       writer._buffers[0][1].should.equal(247);
+      // unicode char
+      value = 'ä';
+      length = value.length;
+      writer.setValues([value]);
+      writer.length.should.equal(4); 
+      writer._buffers[0][2].should.equal(0xC3);
+      writer._buffers[0][3].should.equal(0xA4);
     });
 
     it('should set a BINARY value', function () {