Re: Storing zlib compressed data in a BLOB field

On Mar 20, 2007, at 11:06 AM, Dennis Lee Bieber wrote:

> On Tue, 20 Mar 2007 08:17:08 -0700, Yi Qiang
> <[email protected]> declaimed the following
> in gmane.comp.python.db.pysqlite.user:
>
>> Hello,
>> I am trying to store a cPickled and then zlib compressed object in a
>> BLOB field in my sqlite database.
>> This is the relevant line:
>>              cur.execute(query, (tuple_[1], sqlite3.Binary(tuple_ 
>> [2])))
>> However, when I try to retrieve it back from the database, it appears
>> to be of 'NoneType'.  Any idea what might be going wrong?  If I do
>> not wrap it in sqlite3.Binary, it cuts off part of the data.  For
>> example if what I put in is "'x\x9ck`\x8a-d\xd4\x03\x00\x06\x07\x01
>> \x80'", what I get out is "'x\x9ck`\x8a-d\xd4\x03'"
>>
> 	Well, the truncation looks to be simple to explain... C-standard
> null-terminated string behavior... <G>
>
> 	As for "NoneType"... From "The Definitive Guide to SQLite"
>
> """
> *	If a column's declared type contains the string 'BLOB' (in uppercase
> or lowercase), /or if it has no declared type/, then it is assigned  
> NONE
> affinity.
> """
>
> 	So that much *looks* right... Though if the data itself is coming
> back as None, that may be strange...
>
> 	I've been unable to set up a test case -- my select dies with a
> UTF-8 decode error...
>
Hello Dennis,
I figured out the problem shortly after emailing the list.  I was  
simply storing the wrong thing :)
As for the UTF-8 error, I simply do this to work around it:
         self.con.text_factory = str # Don't want unicode objects back
where self.con = sqlite3.Connection

Cheers,
Yi