django-stdfields 0.0.10

Extra model and form fields for Django: minutes and enumerations

Fields I wish were standard in Django. At the moment this is limited to the MinutesField, EnumIntegerField and EnumCharField.

Contents

• stdfields.forms.MinutesField: use an integer to represent a duration of minutes and hours

• stdfields.fields.EnumIntegerField: makes working with choices a bit easier

• stdfields.fields.EnumCharField: the same, but for choices with a char key

MinutesField

Is an extension of Django’s standard django.forms.IntegerField.

This field will accept values for a duration in minutes in the formats hh:mm or h.fraction, similar to the way BaseCamp allows you to specify your time spent on a task as either 8:30 or 8.5. In the latter case only 8.25, 8.5, 8.50 and 8.75 are considered valid inputs.

Example

Actions speak louder than words:

# models.py
class Task(models.Model):
    time_spent = models.IntegerField()

# forms.py
from stdfields.forms import MinutesField

from models import Task

class TaskForm(forms.ModelForm):
    time_spent = MinutesField(label='How long did it take?')

    class Meta:
        model = Task

You can use the minutes template filter from stdfieldstags to render such a field in the format 8:30:

{% load stdfieldstags %}
It took me {{ task.time_spent|minutes }} to complete this task.

Enumeration

I always end up with ugly code when using Django’s choices argument for fields. With the stdfields.models.Enumeration class, I’ve got a handy base class that allows me to keep things tidy:

# models.py
class Color(Enumeration):
    RED = 'R'
    GREEN = 'G'
    BLUE = 'B'

    @classmethod
    def all(cls):
        return [
            (cls.RED, _(u'Red')),
            (cls.GREEN, _(u'Green')),
            (cls.BLUE, _(u'Blue'))
        ]

class Pencil(models.Model):
    color = models.CharField(choices=Color.all(), max_length=Color.max_length())

# views.py
def red_pencils(request):
    pencils = Pencil.objects.filter(color=Color.RED)
    ...
    # Prints 'Showing the Red pencils'
    logging.info('Showing the %s pencils' % (Color.as_display(Color.RED)))

That could be shorter. Use Enum instead:

# models.py
class Color(Enum):
    RED = EnumValue('R', 'Red')
    GREEN = EnumValue('G', 'Green')
    BLUE = EnumValue('B', 'Blue')

class Pencil(models.Model):
    color = models.CharField(choices=Color.all(), max_length=Color.max_length())

# views.py
def red_pencils(request):
    pencils = Pencil.objects.filter(color=Color.RED)
    ...
    # Prints 'Showing the Red pencils'
    logging.info('Showing the %s pencils' % (Color.RED_display))

EnumCharField and EnumIntegerField

And now we can make working with an Enum easier with the EnumCharField and EnumIntegerField models fields:

# models.py
class Color(Enumeration):
    # same as above

class Pencil(models.Model):
    color = models.EnumCharField(enum=Color, max_length=Color.max_length())

This example is basically the same as the above since EnumCharField is a subclass of the regular Django CharField. By using the enum keyword argument of the enum field, the choices will be automatically updated when you update the enumeration object. And since you’re using the provided max_length method of Enumeration, the max_length will be updated when needed. Just like in the previous example. The enum fields simply offer some more clarity when reading the code.

EnumIntegerField works exactly the same, but for enumerations with integer keys. Both fields can be used with South.