FIX: Encoding Decoding Github issue

Author: jahnvi480

mssql_python/connection.py

@@ -386,6 +386,12 @@ def setencoding(self, encoding=None, ctype=None):
  ddbc_error=f"ctype must be SQL_CHAR ({ConstantsDDBC.SQL_CHAR.value}) or SQL_WCHAR ({ConstantsDDBC.SQL_WCHAR.value})",
  )
 
+ # Enforce UTF-16 encoding restriction for SQL_WCHAR
+ if ctype == ConstantsDDBC.SQL_WCHAR.value and encoding not in UTF16_ENCODINGS:
+ log('warning', "SQL_WCHAR only supports UTF-16 encodings. Attempted encoding '%s' is not allowed. Using default 'utf-16le' instead.", 
+ sanitize_user_input(encoding))
+ encoding = 'utf-16le'
+ 
  # Store the encoding settings
  self._encoding_settings = {
  'encoding': encoding,
@@ -489,13 +495,26 @@ def setdecoding(self, sqltype, encoding=None, ctype=None):
  # Normalize encoding to lowercase for consistency
  encoding = encoding.lower()
 
+ # Enforce UTF-16 encoding restriction for SQL_WCHAR and SQL_WMETADATA
+ if (sqltype == ConstantsDDBC.SQL_WCHAR.value or sqltype == SQL_WMETADATA) and encoding not in UTF16_ENCODINGS:
+ sqltype_name = "SQL_WCHAR" if sqltype == ConstantsDDBC.SQL_WCHAR.value else "SQL_WMETADATA"
+ log('warning', "%s only supports UTF-16 encodings. Attempted encoding '%s' is not allowed. Using default 'utf-16le' instead.", 
+ sqltype_name, sanitize_user_input(encoding))
+ encoding = 'utf-16le'
+ 
  # Set default ctype based on encoding if not provided
  if ctype is None:
  if encoding in UTF16_ENCODINGS:
  ctype = ConstantsDDBC.SQL_WCHAR.value
  else:
  ctype = ConstantsDDBC.SQL_CHAR.value
 
+ # Additional validation: if user explicitly sets ctype to SQL_WCHAR but encoding is not UTF-16
+ if ctype == ConstantsDDBC.SQL_WCHAR.value and encoding not in UTF16_ENCODINGS:
+ log('warning', "SQL_WCHAR ctype only supports UTF-16 encodings. Attempted encoding '%s' is not compatible. Using default 'utf-16le' instead.", 
+ sanitize_user_input(encoding))
+ encoding = 'utf-16le'
+ 
  # Validate ctype
  valid_ctypes = [ConstantsDDBC.SQL_CHAR.value, ConstantsDDBC.SQL_WCHAR.value]
  if ctype not in valid_ctypes: