Adding Custom Data Attributes to ChoiceField in Django 5.0

Based on the Django 5.0/5.1 documentation, there have been changes to how ChoiceField handles choices. In Django 5.0, support for mappings and enumeration types was added to the choices parameter, which might be affecting your previous approach.

Understanding the Issue

The ChoiceField in Django normalizes choices to strings, which means any additional data you might have included in your choice tuples is being lost during processing. This makes it challenging to add custom data attributes to the rendered options.

Possible Solution

You can create a custom widget that extends the Select widget and override the create_option method to add your custom data attributes. Here's an approach that should work with Django 5.0:

PYTHONCopied
from django import forms

class CustomSelect(forms.Select):
    def __init__(self, attrs=None, choices=(), option_attrs=None):
        self.option_attrs = option_attrs or {}
        super().__init__(attrs, choices)
    
    def create_option(self, name, value, label, selected, index, subindex=None, attrs=None):
        option = super().create_option(name, value, label, selected, index, subindex, attrs)
        
        # Add custom data attributes based on the value
        if value in self.option_attrs:
            for key, attr_value in self.option_attrs[value].items():
                option['attrs'][f'data-{key}'] = attr_value
                
        return option

class CustomChoiceField(forms.ChoiceField):
    def __init__(self, option_attrs=None, *args, **kwargs):
        self.option_attrs = option_attrs or {}
        super().__init__(*args, **kwargs)
        self.widget = CustomSelect(choices=self.choices, option_attrs=self.option_attrs)

Usage Example

You can use this custom field in your form like this:

PYTHONCopied
class MyForm(forms.Form):
    # Define your choices
    CHOICES = [
        ('option1', 'Option 1'),
        ('option2', 'Option 2'),
        ('option3', 'Option 3'),
    ]
    
    # Define the custom attributes for each option
    OPTION_ATTRS = {
        'option1': {'count': '10', 'category': 'A'},
        'option2': {'count': '20', 'category': 'B'},
        'option3': {'count': '30', 'category': 'C'},
    }
    
    my_choice = CustomChoiceField(
        choices=CHOICES,
        option_attrs=OPTION_ATTRS,
    )

This approach separates the choice values/labels from the additional attributes you want to add to the HTML, which should work even with Django 5.0's changes to how choices are processed.

Remember that since Django 5.0 normalizes choices to strings, you need to ensure your option_attrs dictionary uses string keys that match the string values of your choices.