Question

我需要使用Python 2.7将Obj-C对象（在这种情况下为NSString）写入sqlite数据库并将其存储在BLOB列中。在这种程度上，我编写了此演示代码，但失败，并没有下面的回溯。

    from sqlite3 import connect
    from Foundation import NSArchiver

    conn = connect(':memory:')
    create = "CREATE TABLE test(data BLOB)"
    conn.execute(create)
    conn.commit()

    blob = NSArchiver.archivedDataWithRootObject_("Hello World").bytes()
    print type(blob), blob
    sql = "INSERT INTO test VALUES (?)"
    data = [blob]

    conn.execute(sql, data)
    conn.commit()

这可以追溯到：

    $ ./sqlite3_test.py
    <type 'memoryview'> <memory at 0x104a5e218>
    Traceback (most recent call last):
      File "./sqlite3_test.py", line 16, in <module>
        conn.execute(sql, data)
    sqlite3.InterfaceError: Error binding parameter 0 - probably unsupported type.

使用sqlite3.Binary（在sqlite3模块中定义为Binary = buffer）或.tobytes()（来自memoryview）的魔术师都无法使效果更好。

我还尝试从NSArchiver Blob中创建一个buffer()对象，但是很简单：

b = buffer(blob, 0, len(blob))

使用TypeError: buffer object expected进行追溯-可以说NSArchiver对象不是Python字符串。

Answer 1

我有一个可行的例子！在Objective-C调用bytes()上，我需要调用memoryview .tobytes()，然后可以将其序列化为buffer()。

#!/usr/bin/python -tt

from sqlite3 import connect, Binary
from Foundation import NSArchiver

conn = connect(':memory:')
create = "CREATE TABLE test(data BLOB)"
conn.execute(create)
conn.commit()

str = NSString.alloc().initWithString_("Hello World")
blob = NSArchiver.archivedDataWithRootObject_(str).bytes().tobytes()
print "Original (%s): %s" % (len(blob), blob)
sql = "INSERT INTO test VALUES (?)"
data = [Binary(blob)]

conn.execute(sql, data)
conn.commit()

cursor = conn.cursor()
cursor.execute("SELECT * FROM test")
rows = cursor.fetchall()
for r in rows:
    print "In database (%s): %s" % (len(r[0]), r[0])

这给出了：

$ ./sqlite3_test.py 
Original (84):
   streamtyped???@???OC_PythonString?NSString?NSObject??i?+
                                                                Hello World?
In database (84):
   streamtyped???@???OC_PythonString?NSString?NSObject??i?+
                                                                Hello World?

如何编写BLOB，任何BLOB到sqlite？

1 个答案: