Re: [gnome-db] GdaCommand.

On Tue, 2009-06-23 at 14:21 +0200, Vivien Malerba wrote:

> 
> 
> 
> 2009/6/23 Bas Driessen <[email protected]>
> 
>         Hello,
>         
>         In V3 there is GdaCommand. I use this to initialize as
>         follows:
>         
>         command = gda_command_new(buffer, GDA_COMMAND_TYPE_TABLE,
>         GDA_COMMAND_OPTION_STOP_ON_ERRORS)
>         
>         Note the parameter GDA_COMMAND_TYPE_TABLE
>         
>         This gave me the option to have a database table be
>         represented in a data model and by adding/editing/deleting
>         rows from the data model, the underlying database table is
>         updated as well. 
>         
>         To be complete the list was as follows:
>         
>         typedef enum { 
>         
>         	GDA_COMMAND_TYPE_SQL,
>         	GDA_COMMAND_TYPE_XML,
>         	GDA_COMMAND_TYPE_PROCEDURE,
>         	GDA_COMMAND_TYPE_TABLE,
>         	GDA_COMMAND_TYPE_SCHEMA,
>         	GDA_COMMAND_TYPE_INVALID
>         } GdaCommandType;
>         
>         
>         How do I use GDA_COMMAND_TYPE_TABLE in V4? Can't find anything
>         in the docs.
> 
> You'll have to create a GdaStatement from the "SELECT * FROM
> table" (which is what was done in V3 BTW). You can do this using a
> parser object, or by creating the object directly (in 4.2 there will
> be an API to build statement without using any SQL).
> 
> Using a parser, your code would be:
> #include <sql-parser/gda-sql-parser.h>
> GdaSqlParser *parser = gda_sql_parser_new ();
> GdaStatement *stmt;
> stmt = gda_sql_parser_parse_string (parser, "SELECT * FROM table",
> NULL, NULL);
> g_object_unref (parser);
> 
> Then execute that statement:
> GdaDataModel *model;
> GError *error = NULL;
> model = gda_connection_statement_execute_select (cnc, stmt, NULL,
> &error);
> if (!model)
>   // handle error
> 
> The returned GdaDataModel is a GdaDataSelect, for which you need to
> call
> gda_data_select_compute_modification_statements (GDA_DATA_SELECT
> (model), &error)
> which should return TRUE if you can modify the data model, and FALSE
> if not (in which case you'll get the reason why in the error pointer).
> If it worked, then you can modify the data model like any other data
> model.
> 
> This is a bit more complicated than in V3 but is much more generic and
> most importantly implemented outside the providers so the behaviour
> will be the same with all providers (which was not the case in V3).
> 

OK, I have implemented this and when I try to remove a row from a data
model I get the error: Model does not allow row deletion. If I try to
append a row, I get the error: No INSERT statement provided. 

Does that mean that this feature is not implemented for this provider,
or am I missing something? I am using postgresql 8.3.7.  If it is not
implemented for postgresql, for which provider is it implemented?



>         
>         Further to this, it appears that all the logic that I have
>         added in the past as recordset_append_row (remove and update)
>         have been removed from the various providers..... ???? . So
>         what is the new way of processing record sets?
> 
> 
> You have gda_data_model_append_row(), gda_data_model_append_values(),
> gda_data_model_set_values() and gda_data_model_remove_row() to modify
> a data model.


Correct, these are available, but they don't appear to work for the
provider postgresql (unless I am doing something wrong). I don't mind
that you have taken out the code I have written, but if it is taken out
and there is no (better) replacement code/alternative then obviously I
have a problem with that.

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