FIX: accept memoryview in Binary() (#741)

Author: bewithgaurav

mssql_python/mssql_python.pyi

@@ -92,7 +92,7 @@ def Timestamp(
 def DateFromTicks(ticks: int) -> datetime.date: ...
 def TimeFromTicks(ticks: int) -> datetime.time: ...
 def TimestampFromTicks(ticks: int) -> datetime.datetime: ...
-def Binary(value: Union[str, bytes, bytearray]) -> bytes: ...
+def Binary(value: Union[str, bytes, bytearray, memoryview]) -> bytes: ...
 
 # DB-API 2.0 Exception Hierarchy
 # https://www.python.org/dev/peps/pep-0249/#exceptions

mssql_python/type.py

@@ -6,6 +6,7 @@
 
 import datetime
 import time
+from typing import Union
 
 
 # Type Objects
@@ -120,15 +121,17 @@ def TimestampFromTicks(ticks: int) -> datetime.datetime:
     return datetime.datetime.fromtimestamp(ticks)
 
 
-def Binary(value) -> bytes:
+def Binary(value: Union[str, bytes, bytearray, memoryview]) -> bytes:
     """
-    Converts a string or bytes to bytes for use with binary database columns.
+    Converts a string or bytes-like object to bytes for binary database columns.
 
-    This function follows the DB-API 2.0 specification.
-    It accepts only str and bytes/bytearray types to ensure type safety.
+    This function follows the DB-API 2.0 specification. It accepts str,
+    bytes, bytearray, and memoryview. memoryview is accepted so buffer-protocol
+    values (for example the memoryview Django hands a BinaryField) round-trip the
+    same way pyodbc handles them.
 
     Args:
-        value: A string (str) or bytes-like object (bytes, bytearray)
+        value: A string (str) or bytes-like object (bytes, bytearray, memoryview)
 
     Returns:
         bytes: The input converted to bytes
@@ -137,18 +140,21 @@ def Binary(value) -> bytes:
         TypeError: If the input type is not supported
 
     Examples:
-        Binary("hello")           # Returns b"hello"
-        Binary(b"hello")          # Returns b"hello"
-        Binary(bytearray(b"hi"))  # Returns b"hi"
+        Binary("hello")                # Returns b"hello"
+        Binary(b"hello")               # Returns b"hello"
+        Binary(bytearray(b"hi"))       # Returns b"hi"
+        Binary(memoryview(b"hi"))      # Returns b"hi"
     """
     if isinstance(value, bytes):
         return value
     if isinstance(value, bytearray):
         return bytes(value)
+    if isinstance(value, memoryview):
+        return value.tobytes()
     if isinstance(value, str):
         return value.encode("utf-8")
     # Raise TypeError for unsupported types to improve type safety
     raise TypeError(
         f"Cannot convert type {type(value).__name__} to bytes. "
-        f"Binary() only accepts str, bytes, or bytearray objects."
+        f"Binary() only accepts str, bytes, bytearray, or memoryview objects."
     )

tests/test_002_types.py

@@ -122,37 +122,60 @@ def test_binary_string_encoding():
     assert result == b"Hello\nWorld\t!", "String with special characters should encode properly"
 
 
+def test_binary_memoryview():
+    """Binary() accepts memoryview (GH-739): Django BinaryField and DB-API buffers."""
+    result = Binary(memoryview(b"\x01\x02\x03"))
+    assert isinstance(result, bytes), "memoryview should be converted to bytes"
+    assert result == b"\x01\x02\x03", "memoryview content should be preserved"
+
+    # Empty memoryview
+    assert Binary(memoryview(b"")) == b""
+
+    # memoryview over a bytearray round-trips the same bytes
+    assert Binary(memoryview(bytearray(b"hello"))) == b"hello"
+
+
 def test_binary_unsupported_types_error():
     """Test Binary() TypeError for unsupported types (Lines 138-141)."""
     # Test integer type
     with pytest.raises(TypeError) as exc_info:
         Binary(123)
     assert "Cannot convert type int to bytes" in str(exc_info.value)
-    assert "Binary() only accepts str, bytes, or bytearray objects" in str(exc_info.value)
+    assert "Binary() only accepts str, bytes, bytearray, or memoryview objects" in str(
+        exc_info.value
+    )
 
     # Test float type
     with pytest.raises(TypeError) as exc_info:
         Binary(3.14)
     assert "Cannot convert type float to bytes" in str(exc_info.value)
-    assert "Binary() only accepts str, bytes, or bytearray objects" in str(exc_info.value)
+    assert "Binary() only accepts str, bytes, bytearray, or memoryview objects" in str(
+        exc_info.value
+    )
 
     # Test list type
     with pytest.raises(TypeError) as exc_info:
         Binary([1, 2, 3])
     assert "Cannot convert type list to bytes" in str(exc_info.value)
-    assert "Binary() only accepts str, bytes, or bytearray objects" in str(exc_info.value)
+    assert "Binary() only accepts str, bytes, bytearray, or memoryview objects" in str(
+        exc_info.value
+    )
 
     # Test dict type
     with pytest.raises(TypeError) as exc_info:
         Binary({"key": "value"})
     assert "Cannot convert type dict to bytes" in str(exc_info.value)
-    assert "Binary() only accepts str, bytes, or bytearray objects" in str(exc_info.value)
+    assert "Binary() only accepts str, bytes, bytearray, or memoryview objects" in str(
+        exc_info.value
+    )
 
     # Test None type
     with pytest.raises(TypeError) as exc_info:
         Binary(None)
     assert "Cannot convert type NoneType to bytes" in str(exc_info.value)
-    assert "Binary() only accepts str, bytes, or bytearray objects" in str(exc_info.value)
+    assert "Binary() only accepts str, bytes, bytearray, or memoryview objects" in str(
+        exc_info.value
+    )
 
     # Test custom object type
     class CustomObject:
@@ -161,7 +184,9 @@ class CustomObject:
     with pytest.raises(TypeError) as exc_info:
         Binary(CustomObject())
     assert "Cannot convert type CustomObject to bytes" in str(exc_info.value)
-    assert "Binary() only accepts str, bytes, or bytearray objects" in str(exc_info.value)
+    assert "Binary() only accepts str, bytes, bytearray, or memoryview objects" in str(
+        exc_info.value
+    )
 
 
 def test_binary_comprehensive_coverage():