Requirements

This application depends on Pint library, used for operate and manipulate physical quantities. Full documentation is available at http://pint.readthedocs.org/

Installation

Install django-quantity-field using pip: pip install django-quantity-field.

Usage

In order to use a quantity field add it to your model definition:

from quantity_field import ureg
from quantity_field.fields import MultiQuantityField

class Package(models.Model):
    size = MultiQuantityField(dim=3, units=(ureg.mm, ureg.cm, ureg.m))
    weight = MultiQuantityField(units=(ureg.g, ureg.kg))

django-quantity-field comes with the custom form field that is used by default for editing in admin or in your forms.

Accessing MultiQuantityField field will returns MultiQuantity object that can be used as ordinary Pint quantities.

>>> from quantity_field.base import MultiQuantity
>>> size = MultiQuantity.from_list(2, 5.5, 4, str(ureg.m))
>>> size
<Quantity(44.0, 'meter ** 3')>
>>> size.dim
3
>>> [v for v in size]
[<Quantity(2.0, 'meter')>, <Quantity(5.5, 'meter')>, <Quantity(4.0, 'meter')>]

Warning

Don’t forget there are no global units in Pint. To use Pint quantities in your project side by side with django-quantity-field use Pint registry from our application.

>>> from quantity_field import ureg
>>> from quantity_field.base import MultiQuantity
>>> box = MultiQuantity.from_string('42 kg')
>>> box + 2.2 * ureg.kg
<Quantity(44.2, 'kilogram')>