[Qt-interest] QSqlTableModel NOT NULL constraints and default values

[Harry Sfougaris]

Thanks for that.
So, i guess there is also no flag or option in a mapper to only generate sql statements for fields that have actually changed?
I am trying to avoid hardcoding my default values in the app. I wonder if in the api you can at least get the default values from the database.

Harry

----- Original message -----
>
> > -----Original Message-----
> > Hi all,
> > I am using a Postgres table that has some fields defined as
> > ....
> >  myFld1 character varying(1024) NOT NULL DEFAULT 'my default
> > value'::character varying,
> > ...
> > I am using a QDataWidgetMapper with a delegate that converts
> > the data in empty text boxes to NULL instead of ''
> > This works with fine with other fields that don't have a NOT
> > NULL constraint.
> >
> > When I am trying to use it with a field that has a NOT NULL
> > constraint though, upon submit() I get the error:
> > "ERROR: null value in column "myFld1" violates not-null
> > constraint. QPSQL: unable to create query"
> >
> > Is there a flag I can set so that the model will allow the
> > query to go to the server, or another solution?
> >
> > Thanks,
>
> Hi Harry,
>
> I haven't used Postgres, but Oracle, Firebird and MSSQL.  In all of those
> three, sending NULL to a NOT NULL column will cause a server error.  The
> DEFAULT clause is only used when the insert statement does not include the
> column.  If you explicitly or implicitly include the column name, then you
> must provide a non NULL value.  I'm not sure whether the Qt drivers provide
> the field's default value for you - that's probably too DBMS specific.  So
> you may need to set that default in your delegate yourself for these fields,
> instead of NULL. 
>
> Hope that helps,
>
> Tony.
>
>
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