RE: [Modeling-users] One to Many Relationships

[Kertis, D. <dk...@vo...>]

Actually,

I had that in my model but got this error:

Serious: couldn't load the model
exceptions.ValueError
invalid literal for int(): *

Here is the code:

<relation=20
			name=3D'topics'
			destinationEntity=3D'Topic'
			deleteRule=3D'2'
			multiplicityLowerBound=3D'0'
			multiplicityUpperBound=3D'*'
thanks,
Dennis





-----Original Message-----
From: Sebastien Bigaret [mailto:sbi...@us...]=20
Sent: Wednesday, August 18, 2004 5:45 AM
To: Kertis, Dennis
Cc: mod...@li...
Subject: Re: [Modeling-users] One to Many Relationships


    Hi Dennis,

  The problem is that you forgot to indicate in your model that it is a
to-many relationship, so the script reacts as if it was a to-one
relationship.  See section 2.5.5. in the User's Guide; a unbound =
to-many
relationship typically defines:

    multiplicityLowerBound=3D'0'
    multiplicityUpperBound=3D'*'

(in your case you got the default values, i.e. respectively '0' and=20
 '1', defining a to-one relationship)


Please also note that there is currently nothing in the framework that
makes sure that your XML-models does not rely on defaults that have
changed between two releases (this is not the case for PyModels, which
defines a 'version' field for this very purpose, see section 2.4.4).
The reason why there is no such mechanism is that the xml model is not
supposed to rely on defaults... even if I fear that this is not said
at all in the User's Guide.

  It does NOT mean you should always specify every possible fields in
your xml model: it just means that you should be careful.  When in =
doubt,
you can easily have your model dumped in another xml model with all its
value defined:

   >>> from Modeling.Model import loadModel
   >>> model=3DloadModel('your_model.xml')
   >>> model.saveModelAsXMLFile('FULLY_QUALIFIED_MODEL.xml')

Just a little warning: be sure to give an other filename, or you'll
overwrite your own model!


-- S=E9bastien.


Kertis, Dennis wrote:
> I am trying to define a one-to-many relationship in XML.  However,
> I am getting the following error:
>=20
> Object: Relationship Category.topics
> ------------------------------------
>  * Error(s):
>    - relationship is not mandatory but source attribute Category.id
>      is required
>
> Can anyone tell me the correct way to model a one-to-many with =
Modeling?
> My "many" table has a foreign key to the primary key of my "one" =
table,
> but modeling doesn't seem to like this.
>
> Below is a cutdown of my model.
>=20
> <entity
>             name=3D'Topic'>
>             <primaryKey attributeName=3D'id'/>
>             <attribute=20
>                   name=3D'id'
>                   type=3D'int'
>                   isRequired=3D'1'/>
>             <attribute=20
>                   name=3D'categoryID'
>                   type=3D'int'
>                   isRequired=3D'1'/>
> </entity>
> <entity
>       name=3D'Category'
> <primaryKey attributeName=3D'id'/>
>       <attribute=20
>                   name=3D'id'
>                   type=3D'int'
>                   isClassProperty=3D'0'=20
>                   isRequired=3D'1'/>
>      <relation=20
>                   name=3D'topics'
>                   destinationEntity=3D'Topic'>
>                   <join=20
>                         sourceAttribute=3D'id'
>                         destinationAttribute=3D'categoryID'/>
> </relation>
> </entity>