python · JelleZijlstra · Apr 22, 2022 · Apr 16, 2022 · Apr 16, 2022 · Apr 16, 2022
@@ -1054,9 +1054,10 @@ Blob Objects
 
 .. class:: Blob
 
-   A :class:`Blob` instance is a :term:`file-like object` that can read and write
-   data in an SQLite :abbr:`BLOB (Binary Large OBject)`.  Call ``len(blob)`` to
-   get the size (number of bytes) of the blob.
+   A :class:`Blob` instance is a :term:`file-like object` with
+   :term:`mapping` support,
+   that can read and write data in an SQLite :abbr:`BLOB (Binary Large OBject)`.
+   Call ``len(blob)`` to get the size (number of bytes) of the blob.
 
    Use the :class:`Blob` as a :term:`context manager` to ensure that the blob
    handle is closed after use.

@@ -33,7 +33,7 @@
     check_disallow_instantiation,
     threading_helper,
 )
-from _testcapi import INT_MAX
+from _testcapi import INT_MAX, ULLONG_MAX
 from os import SEEK_SET, SEEK_CUR, SEEK_END
 from test.support.os_helper import TESTFN, unlink, temp_dir
 
@@ -1162,12 +1162,107 @@ def test_blob_open_error(self):
                 with self.assertRaisesRegex(sqlite.OperationalError, regex):
                     self.cx.blobopen(*args, **kwds)
 
+    def test_blob_length(self):
+        self.assertEqual(len(self.blob), 50)
+
+    def test_blob_get_item(self):
+        self.assertEqual(self.blob[5], b"b")
+        self.assertEqual(self.blob[6], b"l")
+        self.assertEqual(self.blob[7], b"o")
+        self.assertEqual(self.blob[8], b"b")
+        self.assertEqual(self.blob[-1], b"!")
+
+    def test_blob_set_item(self):
+        self.blob[0] = b"b"
+        expected = b"b" + self.data[1:]
+        actual = self.cx.execute("select b from test").fetchone()[0]
+        self.assertEqual(actual, expected)
+
+    def test_blob_set_buffer_object(self):
+        from array import array
+        self.blob[0] = memoryview(b"1")
+        self.blob[0] = bytearray(b"1")
+        self.blob[0] = array("b", [1])
+        self.blob[0:5] = memoryview(b"12345")
+        self.blob[0:5] = bytearray(b"12345")
+        self.blob[0:5] = array("b", [1, 2, 3, 4, 5])
+
+    def test_blob_set_item_negative_index(self):
+        self.blob[-1] = b"z"
+        self.assertEqual(self.blob[-1], b"z")
+
+    def test_blob_get_slice(self):
+        self.assertEqual(self.blob[5:14], b"blob data")
+
+    def test_blob_get_empty_slice(self):
+        self.assertEqual(self.blob[5:5], b"")
+
+    def test_blob_get_slice_negative_index(self):
+        self.assertEqual(self.blob[5:-5], self.data[5:-5])
+
+    def test_blob_get_slice_with_skip(self):
+        self.assertEqual(self.blob[0:10:2], b"ti lb")
+
+    def test_blob_set_slice(self):
+        self.blob[0:5] = b"12345"
+        expected = b"12345" + self.data[5:]
+        actual = self.cx.execute("select b from test").fetchone()[0]
+        self.assertEqual(actual, expected)
+
+    def test_blob_set_empty_slice(self):
+        self.blob[0:0] = b""
+        self.assertEqual(self.blob[:], self.data)
+
+    def test_blob_set_slice_with_skip(self):
+        self.blob[0:10:2] = b"12345"
+        actual = self.cx.execute("select b from test").fetchone()[0]
+        expected = b"1h2s3b4o5 " + self.data[10:]
+        self.assertEqual(actual, expected)
+
+    def test_blob_mapping_invalid_index_type(self):
+        msg = "indices must be integers"
+        with self.assertRaisesRegex(TypeError, msg):
+            self.blob[5:5.5]
+        with self.assertRaisesRegex(TypeError, msg):
+            self.blob[1.5]
+        with self.assertRaisesRegex(TypeError, msg):
+            self.blob["a"] = b"b"
+
+    def test_blob_get_item_error(self):
+        dataset = [len(self.blob), 105, -105]
+        for idx in dataset:
+            with self.subTest(idx=idx):
+                with self.assertRaisesRegex(IndexError, "index out of range"):
+                    self.blob[idx]
+        with self.assertRaisesRegex(IndexError, "cannot fit 'int'"):
+            self.blob[ULLONG_MAX]
+
+    def test_blob_set_item_error(self):
+        with self.assertRaisesRegex(ValueError, "must be a single byte"):
+            self.blob[0] = b"multiple"
+        with self.assertRaisesRegex(TypeError, "doesn't support.*deletion"):
+            del self.blob[0]
+        with self.assertRaisesRegex(IndexError, "Blob index out of range"):
+            self.blob[1000] = b"a"
+
+    def test_blob_set_slice_error(self):
+        with self.assertRaisesRegex(IndexError, "wrong size"):
+            self.blob[5:10] = b"a"
+        with self.assertRaisesRegex(IndexError, "wrong size"):
+            self.blob[5:10] = b"a" * 1000
+        with self.assertRaisesRegex(TypeError, "doesn't support.*deletion"):
+            del self.blob[5:10]
+        with self.assertRaisesRegex(ValueError, "step cannot be zero"):
+            self.blob[5:10:0] = b"12345"
+        with self.assertRaises(BufferError):
+            self.blob[5:10] = memoryview(b"abcde")[::2]
+
     def test_blob_sequence_not_supported(self):
-        with self.assertRaises(TypeError):
+        with self.assertRaisesRegex(TypeError, "unsupported operand"):
             self.blob + self.blob
-        with self.assertRaises(TypeError):
+        with self.assertRaisesRegex(TypeError, "unsupported operand"):
             self.blob * 5
-        with self.assertRaises(TypeError):
+        with self.assertRaisesRegex(TypeError, "is not iterable"):
             b"a" in self.blob
 
     def test_blob_context_manager(self):
@@ -1209,6 +1304,14 @@ def test_blob_closed(self):
                 blob.__enter__()
             with self.assertRaisesRegex(sqlite.ProgrammingError, msg):
                 blob.__exit__(None, None, None)
+            with self.assertRaisesRegex(sqlite.ProgrammingError, msg):
+                len(blob)
+            with self.assertRaisesRegex(sqlite.ProgrammingError, msg):
+                blob[0]
+            with self.assertRaisesRegex(sqlite.ProgrammingError, msg):
+                blob[0:1]
+            with self.assertRaisesRegex(sqlite.ProgrammingError, msg):
+                blob[0] = b""
 
     def test_blob_closed_db_read(self):
         with memory_database() as cx:

diff --git a/Misc/NEWS.d/next/Library/2022-04-14-01-00-31.gh-issue-69093.bmlMwI.rst b/Misc/NEWS.d/next/Library/2022-04-14-01-00-31.gh-issue-69093.bmlMwI.rst
@@ -0,0 +1,2 @@
+Add :term:`mapping` support to :class:`sqlite3.Blob`. Patch by Aviv Palivoda
+and Erlend E. Aasland.
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		Add :term:`mapping` support to :class:`sqlite3.Blob`. Patch by Aviv Palivoda
Comment thread erlend-aasland marked this conversation as resolved. Outdated
		and Erlend E. Aasland.