Re: [Springframework-developer] Exposing LOB support to Jdbc Object layer

[<tho...@tr...>]

Don't know yet where the close of the LobCreator should happen.  Should be
right
after ps.executeUpdate() so we would need to qyery the PreparedStatementCreator
for LOB info somehow.  I have not looked at the batch processing or
MappingSqlQuery usage yet.  

I'm still in the expreimentation stage but I would like to have this ready for
1.1.  We would need to test with various transaction scenarios.  PostgreSQL
requires that you don't run in autocommit mode when you insert a BLOB.

Thomas


Quoting "jürgen höller [werk3AT]" <jue...@we...>:

> That looks interesting! I didn't think about overloaded SqlParameter =
> constructors before; that definitely makes sense. How to you handle the =
> LobCreator lifecycle there? LobCreator.close needs to be invoked after =
> PreparedStatement execution (but before transaction completion).
> 
> BTW, I've recently refined the LOB support for jdbc.core: There are =
> AbstractLobCreatingPreparedStatementCallback and =
> AbstractLobStreamingResultSetExtractor classes now (don't we love our =
> class naming patterns!), to make LOB handling via JdbcTemplate more =
> convenient. Have a look at imagedb's DefaultImageDatabase class for =
> usage examples.
> 
> There's also a ClobStringType class in our Hibernate support, for =
> storing String properties in CLOB fields. That allows to transparently =
> store long Strings in Oracle CLOBs respectively MySQL text fields, for =
> example. It registers a TransactionSynchronization for the =
> LobCreator.close call, so just works within a Spring transaction.
> 
> Juergen
> 
> 
> -----Original Message-----
> From: spr...@li...
> [mailto:spr...@li...]On Behalf
> Of Thomas Risberg
> Sent: Monday, May 03, 2004 2:58 AM
> To: spr...@li...
> Subject: [Springframework-developer] Exposing LOB support to Jdbc Object
> layer
> 
> 
> I've recently started to take a closer look at Juergen's LOB handler=20
> classes and they look very solid.  It would be a shame not exposing them =
> 
> to the Jdbc Object package - primarily SqlUpdate.  I have started to=20
> test a few ideas.  I added a constructor accepting a LobHandler to the=20
> SqlParameter class.  I also added a SqlLobValue class for holding the=20
> input stream and the length.  This is what the usage would look like:
> 
>         LobHandler lobHandler =3D new DefaultLobHandler();  // or=20
> OracleLobHandler
>         String sql =3D "insert into docs (doc_id, description , added,=20
> document) values(?, ?, ?, ?)";
>         SqlUpdate su =3D new SqlUpdate(ds, sql);
>         su.declareParameter(new SqlParameter("id", Types.INTEGER));
>         su.declareParameter(new SqlParameter("desc", Types.VARCHAR));
>         su.declareParameter(new SqlParameter("added", Types.DATE));
>         su.declareParameter(new SqlParameter("lob", Types.BLOB,=20
> lobHandler));
>         su.compile();
>         Object[] inval =3D new Object[4];
>         inval[0] =3D new Integer(newId);
>         inval[1] =3D "Doc One";
>         inval[2] =3D new java.sql.Date(new Date().getTime());
>         File in =3D new File("word.doc");
>         int len =3D (int) in.length();
>         FileInputStream is =3D new FileInputStream(in);
>         inval[3] =3D new SqlLobValue(is, len);
>         int count =3D su.update(inval);
>         is.close();
> 
> A few tweaks to the PreparedStatementCreateorImpl class and this=20
> actually ran against both Oracle and PostgreSQL.
> 
> I think we could easily support all the different methods that=20
> LobHandler supports:
>  byte[]
>  BinaryStream
>  String
>  AsciiStream
>  CharacterStream
> 
> Any thoughts or ideas?
> 
> Thomas
> 
> 
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