[postmodern-devel] Using postgresql's default option for column values

[Marijn Haverbeke]

Hello Peter,

Your problem sounds entirely valid... however, I do not see a
straightforward way to make the DAO classes support this in a
particularly elegant way. In some cases, you can just give the fields
an :initform like (query (:select (:nextval 'my-sequence))). This has
the disadvantage of generating extra queries whenever you create a dao
object. If you think it would be useful, I can add some exception to
the save-dao code to make sure it does not try to save slots that are
unbound -- that way you could just not  initialise the fields that
have default values, and wait until insert time for them to get a
value. Of course, if you need access to these values before saving the
record, this will not help.

Let me know what you think.

Marijn



On Feb 10, 2008 7:28 PM, Peter Eddy <peter.eddy at gmail.com> wrote:
> Hi, new postmodern user here.
>
> I'd like to be able to use postgresql's 'default' column value feature
> instead of an :initform in deftable. Is that possible? I haven't had
> any luck getting it to work.
>
> I have a couple of reasons for wanting to do this, first I have
> several tables that get their primary keys from a single postgresql
> sequence, e.g.:
>
> create table fooA ( id int8 default nextval( 'id_source' ) primary key, ... )
>
> create table fooB ( id int8 default nextval( 'id_source' ) primary key, ... )
>
>
> Additionally, other table columns use the 'default' option to create
> creation time stamps and so forth.
>
> I can't remove these options from the table definitions because that
> would break the other applications that use the database.
>
> So, what I'm really after is the ability to define fields with
> deftable so that those fields are not initialized by (make-instance)
> but read into the dao after creation, similarly to how auto-id appears
> to work.
>
> I looked through the archives but didn't see anything that looked
> related to this.
>
> thanks,
> Peter
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