Re: [SQLObject] Binary data

[Javier R. <jav...@Ho...>]

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Ian,
    Thanks for answering.

Ian Bicking wrote:

> On Saturday, August 9, 2003, at 07:25 PM, Javier Ruere wrote:
>
>>     How can binary data be stored with SQLObject?
>>     I'm trying to pickle something and storing it but caracters are
>> scaped.
>> How can I avoid this?
>>
> This response is a little late, but I don't see another response.
>
> There's an option to Pickle to use a string representation, but that's
> only really a string if all the components can be represented as strings
> (i.e., you don't have any binary instance variables in your objects).

  Yes, I already tried this but doesn't seem to work. For example:

	>>> pickle.dumps('Hello')
	"S'Hello'\np0\n."

  The pickle of 'Hello' has a '\n' in it which when passed through
SQLObject returns as '\\n' which cannot be unpickled. I worked around
this be searching for the function which does this modification, copying
the list of tuples and making the inverse operation.
  Why is this done? I tried storing strings with '\n' in SQLite and it
seems to work alright. Is there a problem with the other DBs? I will be
using this system with SQLite and Postgress eventually so I would be
very interested in knowing this.

> I haven't really used much binary data, so I'm not sure how to represent
> that to the database.  Obviously the data must be escaped somehow.  If
> you figure it out for your database, and say make a dbEscape() function
> that creates the SQL version of the value (complete with '' if
> necessary) you could so something like:
>
> class Binary:
>     def __init__(self, value):
>         self.value = value
>     def sqlRepr(self):
>         return dbEscape(self.value)
>
> You could also use something like base64, like:
>
>     def _set_binaryColumn(self, value):
>          self._SO_set_binaryColumn(value.encode('base64'))
>     def _get_binaryColumn(self):
>          return self._SO_get_binaryColumn().decode('base64')

  I have check this possibility as well but they all count on using '\n'
so there would be little benefit.

Later,
	Javier

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