On Mon, Apr 6, 2015 at 5:32 PM Tiglath Suriol <tiglathsur...@gmail.com>
wrote:
>
> On Monday, April 6, 2015 at 3:02:30 PM UTC-4, Flavia Missi wrote:
>>
>> Hello Tiglath,
>>
>> On Monday, April 6, 2015 at 1:06:43 PM UTC-3, Tiglath Suriol wrote:
>>>
>>>
>>> Environments have servers; servers have applications; applications can
>>> be on various servers, and applications have files.
>>>
>>> - servers must be unique within environments,
>>> - applications must be unique on each server.
>>> - files must be unique within an applications.
>>>
>>> Will this accomplish it?
>>>
>>
>> You're almost there, you just have one relationship wrong: (I'll also add
>> some refactoring suggestions for your attribute names)
>>
>>
>>>
>>>
>>> class Environment(models.Model):
>>>
>>> ''' Environment can be "Production", "QA" or "CT" (customer
>>> test).'''
>>>
>>> env_name = models.CharField('Environment Name', max_length=20)
>>>
>> *env_name* could be only *name* for simplicity, in this case the class
>> Environment (or the environment object) works as a context,
>> so when you're accessing the *name* attribute it'll be cleaner, e.g:
>> >> environ.name # better than environ.env_name
>>
>>
>>>
>>> class Server(models.Model):
>>>
>>> environment = models.ForeignKey(Environment)
>>>
>>> server_name = models.CharField('Server Name', max_length=20,
>>> primary_key=True)
>>>
>>
>> same here, use *name *instead.
>>
>>
>>>
>>>
>>> class Application(models.Model):
>>>
>>> servers = models.ManyToManyField(Server)
>>>
>>> app_name = models.CharField('Application Name', max_length=50,
>>> primary_key=True)
>>>
>>
>> same here, use *name *instead.
>>
>>
>>>
>>>
>>> class File(models.Model):
>>>
>>> applications = models.ManyToManyField(Application)
>>>
>>
>> If you need unique files for application, you should be using a
>> ForeignKey field instead of a ManyToMany.
>>
>>
>>> file_name = models.CharField('File Name', max_length=100,
>>> primary_key=True)
>>>
>>
>> same here, use *name *instead.
>>
>>
>>>
>>>
>>> Thanks
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
>> As far as I see everything else looks fine.
>>
>> Hope it helps!
>>
>
>
> Thank you kindly for your reply.
>
> Actually I have "name" but added the prefixes to the post for clarity.
>
OH, nevermind then x)
> I need files to be unique within an application, but a file with name say,
> "config" could exist in different applications.
>
> Am I right to think that if I use ForeignKey in the File class, as you
> suggest, it will let me just have one file named 'config' overall, but if I
> use ManyToMany with the File name as primary key, there will be only one
> 'config' per Application, but I can have many files named 'config,' say,
> one per app?
>
You're right and wrong at the same time: by making a field unique you're
preventing two records being created with the same value on the unique
field (*name* in your case). It doesn't depend on other relationships
the [File] object might have.
What you might wanna use in this case is unique_together
<https://docs.djangoproject.com/en/dev/ref/models/options/#unique-together>,
using the id and the name as inputs.
Regards,
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