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		@@ -0,0 +1,13 @@
		import sqlite3

		con = sqlite3.connect(":memory:")
		# creating the table
		con.execute("create table test(id integer primary key, blob_col blob)")
		con.execute("insert into test(blob_col) values (zeroblob(10))")
		# opening blob handle
		blob = con.open_blob("test", "blob_col", 1)
		blob.write(b"Hello")
		blob.write(b"World")
		blob.seek(0)
		print(blob.read()) # will print b"HelloWorld"
		blob.close()

12 changes: 12 additions & 0 deletions 12 Doc/includes/sqlite3/blob_with.py

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Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,12 @@
		import sqlite3

		con = sqlite3.connect(":memory:")
		# creating the table
		con.execute("create table test(id integer primary key, blob_col blob)")
		con.execute("insert into test(blob_col) values (zeroblob(10))")
		# opening blob handle
		with con.open_blob("test", "blob_col", 1) as blob:
		blob.write(b"Hello")
		blob.write(b"World")
		blob.seek(0)
		print(blob.read()) # will print b"HelloWorld"

75 changes: 75 additions & 0 deletions 75 Doc/library/sqlite3.rst

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Original file line number	Diff line number	Diff line change
Expand Up		@@ -301,6 +301,21 @@ Connection Objects
		supplied, this must be a callable returning an instance of :class:`Cursor`
		or its subclasses.

		.. method:: open_blob(table, column, row, *, readonly=False, dbname="main")

		On success a :class:`Blob` handle to the
		:abbr:`BLOB (Binary Large OBject)` located in row row,
		column column, table table in database dbname will be returned.
		When readonly is :const:`True` the BLOB is opened with read
		permissions. Otherwise the BLOB has read and write permissions.

		.. note::

		The BLOB size cannot be changed using the :class:`Blob` class. Use
		``zeroblob`` to create the blob in the wanted size in advance.

		.. versionadded:: 3.10

		.. method:: commit()

		This method commits the current transaction. If you don't call this method,
Expand Down Expand Up		@@ -853,6 +868,66 @@ Exceptions
		transactions turned off. It is a subclass of :exc:`DatabaseError`.


		.. _sqlite3-blob-objects:

		Blob Objects
		------------

		.. versionadded:: 3.10

		.. class:: Blob

		A :class:`Blob` instance can read and write the data in the
		:abbr:`BLOB (Binary Large OBject)`. The :class:`Blob` object implement both
		the file and sequence protocol. For example, you can read data from the
		:class:`Blob` by doing ``obj.read(5)`` or by doing ``obj[:5]``.
		You can call ``len(obj)`` to get size of the BLOB.

		.. method:: Blob.close()
Comment thread berkerpeksag Aug 2, 2020 Copy link Copy Markdown Member There was a problem hiding this comment. Choose a reason for hiding this comment The reason will be displayed to describe this comment to others. Learn more. Nitpick: `Blob.*` prefix can be removed. Sorry, something went wrong. Uh oh! There was an error while loading. Please reload this page. All reactions

		Close the BLOB now (rather than whenever __del__ is called).

		The BLOB will be unusable from this point forward; an
		:class:`~sqlite3.Error` (or subclass) exception will be
		raised if any operation is attempted with the BLOB.

		.. method:: Blob.__len__()
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		Return the BLOB size.

		.. method:: Blob.read([size])

		Read size bytes of data from the BLOB at the current offset position.
		If the end of the BLOB is reached we will return the data up to end of
		file. When size is not specified or negative we will read up to end
		of BLOB.

		.. method:: Blob.write(data)

		Write data to the BLOB at the current offset. This function cannot
		changed BLOB length. If data write will result in writing to more
		then BLOB current size an error will be raised.

		.. method:: Blob.tell()

		Return the current offset of the BLOB.

		.. method:: Blob.seek(offset, whence=os.SEEK_SET)

		Set the BLOB offset. The whence argument is optional and defaults to
		:data:`os.SEEK_SET` or 0 (absolute BLOB positioning); other values
		are :data:`os.SEEK_CUR` or 1 (seek relative to the current position) and
		:data:`os.SEEK_END` or 2 (seek relative to the BLOB’s end).

		:class:`Blob` example:

		.. literalinclude:: ../includes/sqlite3/blob.py

		A :class:`Blob` can also be used with :term:`context manager`:

		.. literalinclude:: ../includes/sqlite3/blob_with.py


		.. _sqlite3-types:

		SQLite and Python types
Expand Down

254 changes: 250 additions & 4 deletions 254 Lib/sqlite3/test/dbapi.py

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Original file line number	Diff line number	Diff line change
Expand Up		@@ -511,6 +511,177 @@ def CheckLastRowIDInsertOR(self):
		self.assertEqual(results, expected)


		class BlobTests(unittest.TestCase):
		def setUp(self):
		self.cx = sqlite.connect(":memory:")
		self.cx.execute("create table test(id integer primary key, blob_col blob)")
		self.blob_data = b"a" * 100
		self.cx.execute("insert into test(blob_col) values (?)", (self.blob_data, ))
		self.blob = self.cx.open_blob("test", "blob_col", 1)
		self.second_data = b"b" * 100

		def tearDown(self):
		self.blob.close()
		self.cx.close()

		def CheckLength(self):
		self.assertEqual(len(self.blob), 100)

		def CheckTell(self):
		self.assertEqual(self.blob.tell(), 0)

		def CheckSeekFromBlobStart(self):
		self.blob.seek(10)
		self.assertEqual(self.blob.tell(), 10)
		self.blob.seek(10, 0)
		self.assertEqual(self.blob.tell(), 10)

		def CheckSeekFromCurrentPosition(self):
		self.blob.seek(10, 1)
		self.blob.seek(10, 1)
		self.assertEqual(self.blob.tell(), 20)

		def CheckSeekFromBlobEnd(self):
		self.blob.seek(-10, 2)
		self.assertEqual(self.blob.tell(), 90)

		def CheckBlobSeekOverBlobSize(self):
		with self.assertRaises(ValueError):
		self.blob.seek(1000)

		def CheckBlobSeekUnderBlobSize(self):
		with self.assertRaises(ValueError):
		self.blob.seek(-10)

		def CheckBlobRead(self):
		self.assertEqual(self.blob.read(), self.blob_data)

		def CheckBlobReadSize(self):
		self.assertEqual(len(self.blob.read(10)), 10)

		def CheckBlobReadAdvanceOffset(self):
		self.blob.read(10)
		self.assertEqual(self.blob.tell(), 10)

		def CheckBlobReadStartAtOffset(self):
		self.blob.seek(10)
		self.blob.write(self.second_data[:10])
		self.blob.seek(10)
		self.assertEqual(self.blob.read(10), self.second_data[:10])

		def CheckBlobWrite(self):
		self.blob.write(self.second_data)
		self.assertEqual(self.cx.execute("select blob_col from test").fetchone()[0], self.second_data)

		def CheckBlobWriteAtOffset(self):
		self.blob.seek(50)
		self.blob.write(self.second_data[:50])
		self.assertEqual(self.cx.execute("select blob_col from test").fetchone()[0],
		self.blob_data[:50] + self.second_data[:50])

		def CheckBlobWriteAdvanceOffset(self):
		self.blob.write(self.second_data[:50])
		self.assertEqual(self.blob.tell(), 50)

		def CheckBlobWriteMoreThenBlobSize(self):
		with self.assertRaises(ValueError):
		self.blob.write(b"a" * 1000)

		def CheckBlobReadAfterRowChange(self):
		self.cx.execute("UPDATE test SET blob_col='aaaa' where id=1")
		with self.assertRaises(sqlite.OperationalError):
		self.blob.read()

		def CheckBlobWriteAfterRowChange(self):
		self.cx.execute("UPDATE test SET blob_col='aaaa' where id=1")
		with self.assertRaises(sqlite.OperationalError):
		self.blob.write(b"aaa")

		def CheckBlobWriteWhenReadOnly(self):
		read_only_blob = \
		self.cx.open_blob("test", "blob_col", 1, readonly=True)
		with self.assertRaises(sqlite.OperationalError):
		read_only_blob.write(b"aaa")
		read_only_blob.close()

		def CheckBlobOpenWithBadDb(self):
		with self.assertRaises(sqlite.OperationalError):
		self.cx.open_blob("test", "blob_col", 1, dbname="notexisintg")

		def CheckBlobOpenWithBadTable(self):
		with self.assertRaises(sqlite.OperationalError):
		self.cx.open_blob("notexisintg", "blob_col", 1)

		def CheckBlobOpenWithBadColumn(self):
		with self.assertRaises(sqlite.OperationalError):
		self.cx.open_blob("test", "notexisting", 1)

		def CheckBlobOpenWithBadRow(self):
		with self.assertRaises(sqlite.OperationalError):
		self.cx.open_blob("test", "blob_col", 2)

		def CheckBlobGetItem(self):
		self.assertEqual(self.blob[5], b"a")

		def CheckBlobGetItemIndexOutOfRange(self):
		with self.assertRaises(IndexError):
		self.blob[105]
		with self.assertRaises(IndexError):
		self.blob[-105]

		def CheckBlobGetItemNegativeIndex(self):
		self.assertEqual(self.blob[-5], b"a")

		def CheckBlobGetItemInvalidIndex(self):
		with self.assertRaises(TypeError):
		self.blob[b"a"]

		def CheckBlobGetSlice(self):
		self.assertEqual(self.blob[5:10], b"aaaaa")

		def CheckBlobGetSliceNegativeIndex(self):
		self.assertEqual(self.blob[5:-5], self.blob_data[5:-5])

		def CheckBlobGetSliceInvalidIndex(self):
		with self.assertRaises(TypeError):
		self.blob[5:b"a"]

		def CheckBlobGetSliceWithSkip(self):
		self.blob.write(b"abcdefghij")
		self.assertEqual(self.blob[0:10:2], b"acegi")

		def CheckBlobSetItem(self):
		self.blob[0] = b"b"
		self.assertEqual(self.cx.execute("select blob_col from test").fetchone()[0], b"b" + self.blob_data[1:])

		def CheckBlobSetSlice(self):
		self.blob[0:5] = b"bbbbb"
		self.assertEqual(self.cx.execute("select blob_col from test").fetchone()[0], b"bbbbb" + self.blob_data[5:])

		def CheckBlobSetSliceWithSkip(self):
		self.blob[0:10:2] = b"bbbbb"
		self.assertEqual(self.cx.execute("select blob_col from test").fetchone()[0], b"bababababa" + self.blob_data[10:])

		def CheckBlobGetEmptySlice(self):
		self.assertEqual(self.blob[5:5], b"")

		def CheckBlobSetSliceWrongLength(self):
		with self.assertRaises(IndexError):
		self.blob[5:10] = b"a"

		def CheckBlobConcatNotSupported(self):
		with self.assertRaises(SystemError):
		self.blob + self.blob

		def CheckBlobRepeateNotSupported(self):
		with self.assertRaises(SystemError):
		self.blob * 5

		def CheckBlobContainsNotSupported(self):
		with self.assertRaises(SystemError):
		b"aaaaa" in self.blob

		@unittest.skipUnless(threading, 'This test requires threading.')
		class ThreadTests(unittest.TestCase):
		def setUp(self):
		self.con = sqlite.connect(":memory:")
Expand Down Expand Up		@@ -768,6 +939,15 @@ def CheckClosedCurExecute(self):
		with self.assertRaises(sqlite.ProgrammingError):
		cur.execute("select 4")

		def CheckClosedBlobRead(self):
		con = sqlite.connect(":memory:")
		con.execute("create table test(id integer primary key, blob_col blob)")
		con.execute("insert into test(blob_col) values (zeroblob(100))")
		blob = con.open_blob("test", "blob_col", 1)
		con.close()
		with self.assertRaises(sqlite.ProgrammingError):
		blob.read()

		def CheckClosedCreateFunction(self):
		con = sqlite.connect(":memory:")
		con.close()
Expand Down Expand Up		@@ -921,6 +1101,69 @@ def CheckOnConflictReplace(self):
		self.assertEqual(self.cu.fetchall(), [('Very different data!', 'foo')])



		class ClosedBlobTests(unittest.TestCase):
		def setUp(self):
		self.cx = sqlite.connect(":memory:")
		self.cx.execute("create table test(id integer primary key, blob_col blob)")
		self.cx.execute("insert into test(blob_col) values (zeroblob(100))")

		def tearDown(self):
		self.cx.close()

		def CheckClosedRead(self):
		self.blob = self.cx.open_blob("test", "blob_col", 1)
		self.blob.close()
		with self.assertRaises(sqlite.ProgrammingError):
		self.blob.read()

		def CheckClosedWrite(self):
		self.blob = self.cx.open_blob("test", "blob_col", 1)
		self.blob.close()
		with self.assertRaises(sqlite.ProgrammingError):
		self.blob.write(b"aaaaaaaaa")

		def CheckClosedSeek(self):
		self.blob = self.cx.open_blob("test", "blob_col", 1)
		self.blob.close()
		with self.assertRaises(sqlite.ProgrammingError):
		self.blob.seek(10)

		def CheckClosedTell(self):
		self.blob = self.cx.open_blob("test", "blob_col", 1)
		self.blob.close()
		with self.assertRaises(sqlite.ProgrammingError):
		self.blob.tell()

		def CheckClosedClose(self):
		self.blob = self.cx.open_blob("test", "blob_col", 1)
		self.blob.close()
		with self.assertRaises(sqlite.ProgrammingError):
		self.blob.close()


		class BlobContextManagerTests(unittest.TestCase):
		def setUp(self):
		self.cx = sqlite.connect(":memory:")
		self.cx.execute("create table test(id integer primary key, blob_col blob)")
		self.cx.execute("insert into test(blob_col) values (zeroblob(100))")

		def tearDown(self):
		self.cx.close()

		def CheckContextExecute(self):
		data = b"a" * 100
		with self.cx.open_blob("test", "blob_col", 1) as blob:
		blob.write(data)
		self.assertEqual(self.cx.execute("select blob_col from test").fetchone()[0], data)

		def CheckContextCloseBlob(self):
		with self.cx.open_blob("test", "blob_col", 1) as blob:
		blob.seek(10)
		with self.assertRaises(sqlite.ProgrammingError):
		blob.close()


		def suite():
		module_suite = unittest.makeSuite(ModuleTests, "Check")
		connection_suite = unittest.makeSuite(ConnectionTests, "Check")
Expand All		@@ -931,11 +1174,14 @@ def suite():
		closed_con_suite = unittest.makeSuite(ClosedConTests, "Check")
		closed_cur_suite = unittest.makeSuite(ClosedCurTests, "Check")
		on_conflict_suite = unittest.makeSuite(SqliteOnConflictTests, "Check")
		blob_suite = unittest.makeSuite(BlobTests, "Check")
		closed_blob_suite = unittest.makeSuite(ClosedBlobTests, "Check")
		blob_context_manager_suite = unittest.makeSuite(BlobContextManagerTests, "Check")
		return unittest.TestSuite((
		module_suite, connection_suite, cursor_suite, thread_suite,
		constructor_suite, ext_suite, closed_con_suite, closed_cur_suite,
		on_conflict_suite,
		))
		module_suite, connection_suite, cursor_suite, thread_suite, constructor_suite,
		ext_suite, closed_con_suite, closed_cur_suite, on_conflict_suite,
		blob_suite, closed_blob_suite, blob_context_manager_suite,
		))

		def test():
		runner = unittest.TextTestRunner()
Expand Down

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bpo-24905: Support BLOB incremental I/O in sqlite module #271

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bpo-24905: Support BLOB incremental I/O in sqlite module #271

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berkerpeksag Aug 2, 2020

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