Re: Default column values?

Hmm.  Defaulting can mean a number of things.

1.  Values to be set to the fields when a record is initially created.

2.  Values to be written to the database when a field is null.

3.  Values to be set to fields when a record is 
read and the column in the database is null.

3a. This is marked dirty, so database column 
always updated if it had been null.

3b. This is not marked dirty and does not update upon write.

4.  DDL to be added to Create Table statement.

5.  Values that are not constants but default 
from other records.  Eg.  Department.Default_Salary.

5a. When the record is created or the column is null.

5b. Each time the record is read if no value has 
been set.  Do not write default value back to the database.

6.  Various combinations of the above.


For the first case you can just use an ordinary 
class constructor to set the field values.  Maybe we should add an example.

The other cases get a bit messy.  Which should be 
supported?  DDL is non standard between 
databases.  5b could be the most powerful, but also the most complex.

How useful are they really, or should we just say no?

Anthony


At 06:16 PM 12/11/2008, you wrote:

>Hi,
>
>you're not missing anything, and a default value would indeed be a
>valuable feature.
>
>I think we could think of it, to find where it would best fit :
>rmeta.newRecordInstance, or at a higher level, like dataSet.create(),
>createDetached, ...
>
>Did you already think about it ?
>
>Le mercredi 12 novembre 2008 à 00:18 +0000, cg_ia a écrit :
> > Is there no notion of a column's default value is SimpleORM? For
> > example, when I call SDataSet.create() or SSessionJdbc.create(), I'd
> > like the SRecordInstance that is returned to have default values set
> > on most of its fields. Generators don't seem to fill this roll as far
> > as I can tell, they are only for generating primary key values.
> >
> > I know I can add this functionality by putting my own user property
> > on
> > my SFieldMetas, and wrapping the create() calls, I just wanted to
> > make
> > sure I wasn't missing any built-in functionality.
> >
> >
> >
> >
> >
>
>

Dr Anthony Berglas, [email protected]       Mobile: +61 4 4838 8874
Just because it is possible to push twigs along the ground with ones nose
does not necessarily mean that is the best way to collect firewood.

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