Re: [Pharo-users] Recovering PNG/JPG images that were automatically serialized as FUEL when storing into external database

July 6, 2016

      Bernardo,

To serialize objects in a SQLite data base you do:

================

     | db |
     db := UDBCSQLite3Connection on: self database
     db open.
     db execute:
         'CREATE TABLE IF NOT EXISTS interaction_profiles (
             screenName text PRIMARY KEY,
             avatar blob,
             tweets integer,
             retweets integer
         );'.
     self interactionProfiles do: [ :ip |
         db
             execute: 'INSERT INTO interaction_profiles values (?, ?, ?, 
?);'
             with: { ip screenName . ip avatar . ip tweets . ip retweets}
     ].
     db close.

================

To materialize data you can do:

================

     | query answer |
     query := 'SELECT * FROM interaction_profiles;'.
     answer := (self database open execute: query) rows collect: [ :each 
| each data ].
     self database isOpen ifTrue: [ self database close ].
     answer do: [ :each |
         self interactionProfiles add:
             (TwitterInteractionProfile new
                 screenName: (each at: 'screenName');
                 avatar: (FLMaterializer materializeFromByteArray: (each 
at: 'avatar'));
                 tweets: (each at: 'tweets');
                 retweets: (each at: 'retweets')
                 )
     ]

================

where "self database" gives your sqlite database location. You can find 
especific details on how I'm using this in the Dataviz package:

http://smalltalkhub.com/#!/~Offray/Dataviz

Cheers,

Offray
On 06/07/16 14:18, Bernardo Ezequiel Contreras wrote:
...
Offray,
   could you post a snippet of the code to serialize and materialize 
an object and insert it into the sqlite database, please?
  just what's needed in order to get the idea
thanks;
On Wed, Jul 6, 2016 at 3:00 PM, Offray Vladimir Luna CÃ¡rdenas 
<offray.luna@mutabit.com <mailto:offray.luna@mutabit.com>> wrote:
Hi Pierce,
I was my fault. I was not understanding properly the way of
    materialize back the png/jpeg images. With Max's help in the Slack
    chat channel it was clearer. Now is working properly and I have
    updated the database query messages accordingly.
This combination of Fuel + SQLite seems very promising. For the
    moment I'm using mostly Fuel with the same efficiency of SQLite
    for external storage: 27 Mb both, the sqlite file and the fuel
    one, and almost the same reading time and without the impedance of
    object object-relational mapping. I imagine that the more we start
    to query the data, the more we're going to rely on SQLite bindings.
Cheers,
Offray
On 04/07/16 22:51, Pierce Ng wrote:
...
On Sat, Jul 02, 2016 at 10:01:14PM -0500, Offray Vladimir Luna CÃ¡rdenas wrote:
...
I can read the blobs from SQLite. The problem is that they're stored
    as FUEL inside SQLite and I don't know how to read them back to
    recover the png/jpeg image that was serialized that way.
UDBCSQLite uses Fuel to serialize/materialize objects that aren't integers,
    real numbers and strings. Sounds like you've hit a bug, whereby your png/jpg
    files are serialized but aren't being materialized when read back, so you're
    getting back raw byte arrays.
Can you provide simple schema and code fragment to reproduce the problem
    please.
Pierce
-- 
Bernardo E.C.
Sent from a cheap desktop computer in South America.