Generics in Django - django

Question

Could someone translate this Java Pseudo code with generics to Django models? I don't understand the content type concept. It would also be possible to leave out the map and just have a list of KeyValuePairs or KeyValueExamples.
class Dictionary<T extends KeyValuePair>
class KeyValuePair
String key
String value
class KeyValueExample extends KeyValuePair
String example
class Container
Dictionary<KeyValuePair> itemsOne
Dictionary<KeyValueExample> itemsTwo

Answer 1

Django's contenttypes doesn't have anything common with generics from Java. Python has a dynamic type system so there is no need for generics.
This means that you can put any object of any class into the dictionary:
class Container(object):
def __init__(self):
self.itemsOne = {}
self.itemsTwo = {}
container = Container()
container.itemsOne['123'] = '123'
container.itemsOne[321] = 321
container.itemsTwo[(1,2,3)] = "tuple can be a key"
If you want to implement your classes in django models then code could be something like this:
class KeyValuePairBase(models.Model):
key = models.CharField(max_length=30)
value = models.CharField(max_length=30)
class Meta:
abstract = True
class KeyValuePair(KeyValuePairBase):
pass
class KeyValueExample(KeyValuePairBase):
example = models.CharField(max_length=30)
class Container(models.Model):
items_one = models.ManyToManyField(KeyValuePair)
items_two = models.ManyToManyField(KeyValueExample)
# usage of these models
kvp = KeyValuePair.objects.create(key='key', value='value')
kve = KeyValueExample.objects.create(key='key', value='value',
example='Example text')
container = Container.objects.create()
container.items_one.add(kvp)
container.items_two.add(kve)