So you're basically trying to implement EAV [1]? There exists few apps that does it for you, like django-eav:
https://github.com/mvpdev/django-eav [1] http://en.wikipedia.org/wiki/Entity%E2%80%93attribute%E2%80%93value_model On Thu, Apr 12, 2012 at 6:34 PM, trubliphone <[email protected]> wrote: > All, > > I am at my wit's end trying to come up with a structure to do the > following. I have a "MasterModel" that acts as a template for an > "InstanceModel." The MasterModel defines a set of name/value pairs. > Each InstanceModel must have a name that corresponds to one of the > names of the MasterModel and a value chosen from the set of values of > that same MasterModel. So far I have the following code: > > class MasterModel(models.Model): > name = models.CharField() > values = MasterValueField() > > (MasterValueField is a custom field class that overloads "to_python" > and "value_to_string" such that it stores a string in the database but > returns a list of tuples in Python - of the sort that can be passed to > the "choices" attribute of a field.) > > class InstanceModel(models.Model): > name = models.CharField() > values = models.CharField() > > def __init__(self,*args,**kwargs): > # not sure if this is a good way to do things > master = kwargs.pop("master",None) > super(InstanceModel,self).__init__(*args,*kwargs) > if master: > self._meta.get_field_by_name("name")[0].default = master.name > self._meta.get_field_by_name("value")[0]._choices = master.values > > Now I have a class with a relationship to InstanceModel: > > class MyClass(models.Model): > myField = models.CharField() > myOtherField = models.CharField() > instances = models.ManyToManyField("InstanceModel") > > There is a form based on MyClass, and a formset based on > InstanceModel. These both get rendered properly in the view. What I > am struggling with is figuring out how to initialize the instances. > > When I add a new InstanceModel form in the formset, how can I ensure > that its name/value fields are constrained by the name/value fields of > an appropriate MasterModel? > > I hope this is clear. > > Many thanks for your help. > > -- > You received this message because you are subscribed to the Google Groups > "Django users" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/django-users?hl=en. > > -- Jani Tiainen - Well planned is half done, and a half done has been sufficient before... -- You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/django-users?hl=en.
