[Gambas-devel] Database driver update in 1.9.23

[Daniel]

Benoit Minisini wrote:

>Here is more explanations about the database driver update of 1.9.23:
>
>
>(1) The DB_DATABASE structure has changed.
>
>Before, it was just a cast to the underlying connection handle. Now it is the 
>following structure:
>
>typedef
>  struct {
>    void *handle;	/* Connection handle */
>    long version;	/* Version of the database system */
>    char *charset;	/* Charset used by the database */
>    void *data;		/* Can be used by the driver for storing its 
>			own private data */
>    struct {
>      unsigned no_table_type : 1;	/* Tables do not have types */
>      unsigned no_serial : 1;		/* Serial fields are not supported */
>      unsigned no_blob : 1;		/* Blob fields are not supported */
>      unsigned no_seek : 1;		/* Cannot seek anywhere in a Result */
>      }
>      flags;
>  }
>DB_DATABASE;
>
>All drivers functions that took a DB_DATABASE argument were (or have to be) 
>modified so that they receive now a DB_DATABASE pointer argument.
>
>The interface of open_database() driver function has changed. Now this 
>function must fill the DB_DATABASE structure.
>
>As the database version is stored in this structure, the 'version' argument of 
>some driver functions has been removed.
>
>
>(2) Two new functions must be implemented in a database driver:
>
>* format_blob(): This function transforms a blob value into a string value 
>that can be inserted into a SQL query.
>
>* blob_read(): Returns the value of a BLOB field.
>
>As usual, these functions are documented in the postgresql driver.
>
>They are void stubs in the sqlite2 driver, as sqlite2 does not support blobs.
>
>
>(3) Two new constants were added that represent new field datatypes:
>
>* DB_T_SERIAL, for autoincrement fields.
>* DB_T_BLOB, for blob fields.
>
>
>(4) A special comment for Nigel :-)
>
>SQLite driver dataset C++ function is a mess. The guy who wrote it did a very 
>bad C++ job. 
>
>At the moment, I had to hack them to support blobs. But when you read a blob 
>field, its contents are copied three times by this API before raising the 
>Gambas user variables!
>
>I think all that *@#! must be destroyed, and that I should make an emulation 
>of direct-access result set in the database component for database backends 
>that only support forward-only result set. It will benefits ODBC drivers that 
>are in the same situation.
>
>
>(5) A special comment for Andrea :-)
>
>The implementation of autoincrement field and blob is just a stub at the 
>moment. I don't know ODBC enough to do the job. Good luck!
>
>
>(6) A special comment for Daniel :-)
>
>Same remark for Firebird. I have the source, but I can't compile it because of 
>missing libraries on Mandriva :-(
>
>Best regards to all three,
>
>  
>
hi benoit
i don't understand
i read the postgres driver and i don't see who call read_blob and 
format_blob
the call is in the driver or in gambas
i make more test and it is any time query_fill called for blob!!!

daniel