Django MultiWidget Phone Number Field

Question

I want to create a field for phone number input that has 2 text fields (size 3, 3, and 4 respectively) with the common "(" ")" "-" delimiters. Below is my code for the field and the widget, I'm getting the following error when trying to iterate the fields in my form during initial rendering (it happens when the for loop gets to my phone number field):

Caught an exception while rendering: 'NoneType' object is unsubscriptable

class PhoneNumberWidget(forms.MultiWidget):
    def __init__(self,attrs=None):
        wigs = (forms.TextInput(attrs={'size':'3','maxlength':'3'}),\
                forms.TextInput(attrs={'size':'3','maxlength':'3'}),\
                forms.TextInput(attrs={'size':'4','maxlength':'4'}))
        super(PhoneNumberWidget, self).__init__(wigs, attrs)

    def decompress(self, value):
        return value or None

    def format_output(self, rendered_widgets):
        return '('+rendered_widgets[0]+')'+rendered_widgets[1]+'-'+rendered_widgets[2]

class PhoneNumberField(forms.MultiValueField):
    widget = PhoneNumberWidget
    def __init__(self, *args, **kwargs):
        fields=(forms.CharField(max_length=3), forms.CharField(max_length=3), forms.CharField(max_length=4))
        super(PhoneNumberField, self).__init__(fields, *args, **kwargs)
    def compress(self, data_list):
        if data_list[0] in fields.EMPTY_VALUES or data_list[1] in fields.EMPTY_VALUES or data_list[2] in fields.EMPTY_VALUES:
            raise fields.ValidateError(u'Enter valid phone number')
        return data_list[0]+data_list[1]+data_list[2]

class AdvertiserSumbissionForm(ModelForm):
    business_phone_number = PhoneNumberField(required=True)

Answer 1

This uses widget.value_from_datadict() to format the data so no need to subclass a field, just use the existing USPhoneNumberField. Data is stored in db like XXX-XXX-XXXX.

from django import forms

class USPhoneNumberMultiWidget(forms.MultiWidget):
    """
    A Widget that splits US Phone number input into three <input type='text'> boxes.
    """
    def __init__(self,attrs=None):
        widgets = (
            forms.TextInput(attrs={'size':'3','maxlength':'3', 'class':'phone'}),
            forms.TextInput(attrs={'size':'3','maxlength':'3', 'class':'phone'}),
            forms.TextInput(attrs={'size':'4','maxlength':'4', 'class':'phone'}),
        )
        super(USPhoneNumberMultiWidget, self).__init__(widgets, attrs)

    def decompress(self, value):
        if value:
            return value.split('-')
        return (None,None,None)

    def value_from_datadict(self, data, files, name):
        value = [u'',u'',u'']
        # look for keys like name_1, get the index from the end
        # and make a new list for the string replacement values
        for d in filter(lambda x: x.startswith(name), data):
            index = int(d[len(name)+1:]) 
            value[index] = data[d]
        if value[0] == value[1] == value[2] == u'':
            return None
        return u'%s-%s-%s' % tuple(value)

use in a form like so:

from django.contrib.localflavor.us.forms import USPhoneNumberField
class MyForm(forms.Form):
    phone = USPhoneNumberField(label="Phone", widget=USPhoneNumberMultiWidget())

Answer 2

I think the value_from_datadict() code can be simplified to:

class USPhoneNumberMultiWidget(forms.MultiWidget):
    """
    A Widget that splits US Phone number input into three  boxes.
    """
    def __init__(self,attrs=None):
        widgets = (
            forms.TextInput(attrs={'size':'3','maxlength':'3', 'class':'phone'}),
            forms.TextInput(attrs={'size':'3','maxlength':'3', 'class':'phone'}),
            forms.TextInput(attrs={'size':'4','maxlength':'4', 'class':'phone'}),
        )
        super(USPhoneNumberMultiWidget, self).__init__(widgets, attrs)

    def decompress(self, value):
        if value:
            return value.split('-')
        return [None,None,None]

    def value_from_datadict(self, data, files, name):
        values = super(USPhoneNumberMultiWidget, self).value_from_datadict(data, files, name)
        return u'%s-%s-%s' % values

The value_from_datadict() method for MultiValueWidget already does the following:

    def value_from_datadict(self, data, files, name):
        return [widget.value_from_datadict(data, files, name + '_%s' % i) for i, widget in enumerate(self.widgets)]

Answer 3

I took hughdbrown's advise and modified USPhoneNumberField to do what I need. The reason I didn't use it initially was that it stores phone numbers as XXX-XXX-XXXX in the DB, I store them as XXXXXXXXXX. So I over-rode the clean method:

class PhoneNumberField(USPhoneNumberField):
    def clean(self, value):
        super(USPhoneNumberField, self).clean(value)
        if value in EMPTY_VALUES:
            return u''
        value = re.sub('(\(|\)|\s+)', '', smart_unicode(value))
        m = phone_digits_re.search(value)
        if m:
            return u'%s%s%s' % (m.group(1), m.group(2), m.group(3))
        raise ValidationError(self.error_messages['invalid'])

Answer 4

Sometimes it is useful to fix the original problem rather than redoing everything. The error you got, "Caught an exception while rendering: 'NoneType' object is unsubscriptable" has a clue. There is a value returned as None(unsubscriptable) when a subscriptable value is expected. The decompress function in PhoneNumberWidget class is a likely culprit. I would suggest returning [] instead of None.