django-ordered-model allows models to be ordered and provides a simple admin interface for reordering them.
Based on https://djangosnippets.org/snippets/998/ and https://djangosnippets.org/snippets/259/
Requires:
- Django >=1.5
- Python >=2.6 or >=3.3
$ python setup.py install
You can use Pip:
$ pip install django-ordered-model
Add ordered_model
to your SETTINGS.INSTALLED_APPS
.
Inherit your model from OrderedModel
to make it ordered:
from django.db import models
from ordered_model.models import OrderedModel
class Item(OrderedModel):
name = models.CharField(max_length=100)
class Meta(OrderedModel.Meta):
pass
Model instances now have a set of methods to move them relative to each other.
To demonstrate those methods we create two instances of Item
:
foo = Item.objects.create(name="Foo")
bar = Item.objects.create(name="Bar")
foo.swap(bar)
This swaps the position of two objects.
foo.up()
foo.down()
Moving an object up or down just makes it swap its position with the neighouring object directly above of below depending on the direction.
foo.to(12)
bar.to(13)
Move the object to an arbitrary position in the stack. This essentially sets the order value to the specified integer. Objects between the original and the new position get their order value increased or decreased according to the direction of the move.
foo.above(bar)
foo.below(bar)
Move the object directly above or below the reference object, increasing or decreasing the order value for all objects between the two, depending on the direction of the move.
foo.top()
This sets the order value to the lowest value found in the stack and increases the order value of all objects that were above the moved object by one.
foo.bottom()
This sets the order value to the highest value found in the stack and decreases the order value of all objects that were below the moved object by one.
In some cases, ordering objects is required only on a subset of objects. For example,
an application that manages contact lists for users, in a many-to-one/many relationship,
would like to allow each user to order their contacts regardless of how other users
choose their order. This option is supported via the order_with_respect_to
parameter.
A simple example might look like so:
class Contact(OrderedModel):
user = models.ForeignKey(User)
phone = models.CharField()
order_with_respect_to = 'user'
In a many-to-many relationship you need to use a seperate through model which is derived from the OrderedModel. For example, an application which manages pizzas with toppings.
A simple example might look like so:
class Topping(models.Model):
name = models.CharField(max_length=100)
class Pizza(models.Model):
name = models.CharField(max_length=100)
toppings = models.ManyToManyField(Topping, through='PizzaToppingsThroughModel')
class PizzaToppingsThroughModel(OrderedModel):
pizza = models.ForeignKey(Pizza)
topping = models.ForeignKey(Topping)
order_with_respect_to = 'pizza'
class Meta:
ordering = ('pizza', 'order')
When you want ordering on the baseclass instead of subclasses in an ordered list of objects of various classes, specify the full module path of the base class:
class BaseQuestion(OrderedModel):
order_class_path = __module__ + '.BaseQuestion'
question = models.TextField(max_length=100)
class Meta:
ordering = ('order',)
class MultipleChoiceQuestion(BaseQuestion):
good_answer = models.TextField(max_length=100)
wrong_answer1 = models.TextField(max_length=100)
wrong_answer2 = models.TextField(max_length=100)
wrong_answer3 = models.TextField(max_length=100)
class OpenQuestion(BaseQuestion):
answer = models.TextField(max_length=100)
To add arrows in the admin change list page to do reordering, you can use the
OrderedModelAdmin
and the move_up_down_links
field:
from django.contrib import admin
from ordered_model.admin import OrderedModelAdmin
from models import Item
class ItemAdmin(OrderedModelAdmin):
list_display = ('name', 'move_up_down_links')
admin.site.register(Item, ItemAdmin)
For a many-to-many relationship you need the following in the admin.py file:
from django.contrib import admin
from ordered_model.admin import OrderedTabularInline
from models import Pizza, PizzaToppingsThroughModel
class PizzaToppingsThroughModelInline(OrderedTabularInline):
model = PizzaToppingsThroughModel
fields = ('topping', 'order', 'move_up_down_links',)
readonly_fields = ('order', 'move_up_down_links',)
extra = 1
ordering = ('order',)
class PizzaAdmin(admin.ModelAdmin):
list_display = ('name', )
inlines = (PizzaToppingsThroughModelInline, )
def get_urls(self):
urls = super(PizzaAdmin, self).get_urls()
for inline in self.inlines:
if hasattr(inline, 'get_urls'):
urls = inline.get_urls(self) + urls
return urls
admin.site.register(Pizza, PizzaAdmin)
Requires Docker.
$ script/test