modeling-users

[Modeling-users] Some more corrections to the documentation (manual) and some questios

[Ernesto R. <er...@si...>]

Hi,

in section  2.4.7.3 RToMany, it says:
RToOne objects describe a to-many relationship ... should be RToMany

in section 2.4.8 Association : incorrect spelling: shortvut should be =
shortcut

in section 2.6.3.2 A short example:=20
Now that we now.... should read Now that we know...


Question: in secion 2.4.8 Association, in the 'Important' part it says:
Association objects always define a to-one association from the first =
entity to the second entity, and an inverse to-many relationship from =
the second entity to the first one.

Is this true, although the multiplicity has no be defined as:
              multiplicity=3D[ [0, 1], [0, None] ],
like
              multiplicity=3D[ [0, None], [0, 1] ],

?

If the foreign key value must not be null, e.g. like the 'customer' =
field . for invoices, orders, etc., the multiplicity would be:           =
   [1, 1], [0, None]
as in:
    Association('Invoice', 'Customer', =
relations=3D['customer','invoices'],
                multiplicity=3D[ [1, 1] , [0, None] ],
                delete=3D['nullify','deny'])
??

Generation of DB-Schema with mdl_generate_DB_schema.py:
When I do:
    python p:mdl_generate_DB_schema.py -c -v -C modelo.py

I get:
    Error: option -C requires --admin-connection-dict
1.) I don't access the DB (-c option) so a admin dictionary should not =
be needed.
2.) there is no --admin-connection-dict parameter, only a --admin-dsn =
parameter


Best regards, Erny

Re: [Modeling-users] Some more corrections to the documentation (manual) and some questios

[Sebastien B. <sbi...@us...>]

        Hi ,

"Ernesto Revilla" <er...@si...> wrote:
> Question: in secion 2.4.8 Association, in the 'Important' part it says:
> Association objects always define a to-one association from the first ent=
ity to the second entity, and an inverse to-many relationship from the seco=
nd entity to the first one.
>=20
> Is this true, although the multiplicity has no be defined as:
>               multiplicity=3D[ [0, 1], [0, None] ],
> like
>               multiplicity=3D[ [0, None], [0, 1] ],
>=20
> ?

Yes, this is true, if you try to inverse toOne/toMany multiplicities
you'll get a "ValueError: invalid multiplicity dst->src: should be
toMany"

>=20
> If the foreign key value must not be null, e.g. like the 'customer' field=
 . for invoices, orders, etc., the multiplicity would be:              [1, =
1], [0, None]
> as in:
>     Association('Invoice', 'Customer', relations=3D['customer','invoices'=
],
>                 multiplicity=3D[ [1, 1] , [0, None] ],
>                 delete=3D['nullify','deny'])
> ??

Right: a lower bound=3D=3D1 requires any invoice to have exactly one custom=
er.

> Generation of DB-Schema with mdl_generate_DB_schema.py:
> When I do:
>     python p:mdl_generate_DB_schema.py -c -v -C modelo.py
>=20
> I get:
>     Error: option -C requires --admin-connection-dict
> 1.) I don't access the DB (-c option) so a admin dictionary should not be=
 needed.
> 2.) there is no --admin-connection-dict parameter, only a --admin-dsn par=
ameter

  You're absolutely right --for both the typo. and the fact that we
should probably just issue a warning if -c is set while --admin-dsn
would be required without -c.


  And thank you for the doc. corrections and the enhancement proposal.
  I'll look at them closely this week-end and integrate the corrections
  then. Thanks again.

-- S=E9bastien.