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/
See our compatability notes for the appropriate version to use with older Django and Python releases.
$ 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 neighbouring 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.
For performance reasons, the delete(), to(), below(), above(), top(), and bottom() methods use Django's update() method to change the order of other objects that are shifted as a result of one of these calls. If the model has fields that are typically updated in a customized save() method, or through other app level functionality such as DateTimeField(auto_now=True), you can add additional fields to be passed through to update(). This will only impact objects where their order is being shifted as a result of an operation on the target object, not the target object itself.
foo.to(12, extra_update={'modified': now()}
foo.previous()
foo.next()
previous() and next() get the neighbouring objects directly above of below within the ordered stack depending on the direction.
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, on_delete=models.CASCADE)
phone = models.CharField()
order_with_respect_to = 'user'
If objects are ordered with respect to more than one field, order_with_respect_to
supports
tuples to define multiple fields:
class Model(OrderedModel)
# ...
order_with_respect_to = ('field_a', 'field_b')
In a many-to-many relationship you need to use a separate 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, on_delete=models.CASCADE)
topping = models.ForeignKey(Topping, on_delete=models.CASCADE)
order_with_respect_to = 'pizza'
class Meta:
ordering = ('pizza', 'order')
You can also specify order_with_respect_to
to a field on a related model. An example use-case can be made with the following models:
class ItemGroup(models.Model):
user = models.ForeignKey(User, on_delete=models.CASCADE)
general_info = models.CharField(max_length=100)
class GroupedItem(OrderedModel):
group = models.ForeignKey(ItemGroup, on_delete=models.CASCADE)
specific_info = models.CharField(max_length=100)
order_with_respect_to = 'group__user'
Here items are put into groups that have some general information used by its items, but the ordering of the items is independent of the group the item is in.
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 one of the following inlines.
OrderedTabularInline
or OrderedStackedInline
just like the django admin.
For the OrderedTabularInline
it will look like this:
from django.contrib import admin
from ordered_model.admin import OrderedTabularInline, OrderedInlineModelAdminMixin
from models import Pizza, PizzaToppingsThroughModel
class PizzaToppingsThroughModelTabularInline(OrderedTabularInline):
model = PizzaToppingsThroughModel
fields = ('topping', 'order', 'move_up_down_links',)
readonly_fields = ('order', 'move_up_down_links',)
extra = 1
ordering = ('order',)
class PizzaAdmin(OrderedInlineModelAdminMixin, admin.ModelAdmin):
list_display = ('name', )
inlines = (PizzaToppingsThroughModelTabularInline, )
admin.site.register(Pizza, PizzaAdmin)
For the OrderedStackedInline
it will look like this:
from django.contrib import admin
from ordered_model.admin import OrderedStackedInline, OrderedInlineModelAdminMixin
from models import Pizza, PizzaToppingsThroughModel
class PizzaToppingsThroughModelStackedInline(OrderedStackedInline):
model = PizzaToppingsThroughModel
fields = ('topping', 'order', 'move_up_down_links',)
readonly_fields = ('order', 'move_up_down_links',)
extra = 1
ordering = ('order',)
class PizzaAdmin(OrderedInlineModelAdminMixin, admin.ModelAdmin):
list_display = ('name', )
inlines = (PizzaToppingsThroughModelStackedInline, )
admin.site.register(Pizza, PizzaAdmin)
Requires Docker.
$ script/test
django-ordered-model version | Django version | Python version |
---|---|---|
3.1.x | 2.x | 3.4 and above |
3.0.x | 2.x | 3.4 and above |
2.1.x | 1.x | 2.7 to 3.6 |
2.0.x | 1.x | 2.7 to 3.6 |