Hi all,
I am trying to find a best way to solve the following problem:
I have chemicals, each of which has a list of codes and names.
Chemicals have too many codes and names to put directly into the
Chemical model.
Example (pseudo) models.py:
class Chemical():
pass
class Name():
chemical = ForeignKey(Chemical)
nametype = Integer # in reality a foreign key
name = varchar(50)
unique_together(chemical, nametype)
class Code():
chemical = ForeignKey(Chemical)
codetype = Integer
code = varchar(50)
unique_together(chemical, codetype)
I need to make listings of these chemicals, (chemical_id, name, code),
and I need to change dynamically which name and which code to show.
Naturally the listings need to be searchable.
The most beautiful solution would be the possibility to directly use:
Chemical.objects.filter(code__codetype = 1).filter(name__nametype =
1)\
.filter(code__code__contains = '123').values
('pk','code__code', 'name__name')
but Django orm can't handle this currently. I actually looked into the
code to see how hard this would be to implement for values and
values_list. I quickly saw that this is not something you want to do
as your first Django coding project...
So far I have a few solutions to this problem.
1) Use raw sql
- works, but is ugly
2) Create a database view and a corresponding model, and use that for
listings
- works, but is after all only marginally better than solution 1.
Biggest problem is that it is not DRY.
3) Filter both Name and Code manually, then join them in python.
- I haven't really tried this one. I think this is the ugliest so
far.
I am currently using solution 2. but I am wondering if there is some
better way to do this? Maybe using .extra() in some way?
By the way, I have just switched to Django from JDBC + jsp. I can't
believe how easy web programming can be with the right tools. Thank
you!
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