Django RadioSelect widget, add additional information - django

Question

I have this simplified model and form:
class Books(models.Model):
name = models.CharField(max_length=500)
price = models.DecimalField(max_digits=6, decimal_places=2)
default = models.BooleanField(default=False)
def __str__(self):
return self.name
class BookForm(forms.Form):
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
self.fields['Field'] = forms.ModelChoiceField(queryset=None, empty_label=None, widget=forms.RadioSelect)
self.fields['Field'].queryset = Books.objects.all()
self.fields['Field'].initial = Books.objects.filter(default=True).first()
This will result in a RadioSelect-Form, like this:
(x) Book1
( ) Book2
( ) Book3
My problem is, how can I add the price in the RadioSelect form, that it's just visible.
It should appear after the name of the book, ideally even in a different font, which I set over a bootstrap class (e.g "text-primary") (this is not mandatory)
(x) Book1 (10 €)
( ) Book2 (20 €)
( ) Book3 (30 €)
I know i can return the name and price in the model, like
class Books(models.Model):
name = models.CharField(max_length=500)
price = models.DecimalField(max_digits=6, decimal_places=2)
default = models.BooleanField(default=False)
def __str__(self):
return '%s (%s €)' % (self.value, str(self.price))
But because of other reasons, i can not do this. I just need to return the name. Are there other ways to do this?
I even read into django-crispy-forms, but couldnt find a solution.

Answer 1

You can use .label_from_instance.
From the documentation:
The __str__() method of the model will be called to generate string representations of the objects for use in the field’s choices. To provide customized representations, subclass ModelChoiceField and override label_from_instance.
You can define a function that gives you the representation that you want and then set .label_from_instance on your field.
Your BookForm then looks like this:
class BookForm(forms.Form):
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
self.fields['Field'] = forms.ModelChoiceField(queryset=None, empty_label=None, widget=forms.RadioSelect)
self.fields['Field'].queryset = Books.objects.all()
self.fields['Field'].initial = Books.objects.filter(default=True).first()
# customize how your option is rendered in the template
self.fields["Field"].label_from_instance = lambda item: f"{item} ({item.price} €)"
To apply CSS on the label add HTML. Instead of using style='...' you can also use classes so it works with Bootstrap.
self.fields["Field"].label_from_instance = lambda item: f"{item} <span style='color:red;'>({item.price} €)</span>"
For Python versions before 3.7:
self.fields["Field"].label_from_instance = lambda item: str(item) + "<span style='color:red;'>(" + str(item.price) + " €)</span>"
Then render your form in the template like this:
<form action="{% url 'books' %}" method="post">
{% csrf_token %}
{% for hidden_field in form.hidden_fields %}
{{ hidden_field }}
{% endfor %}
<ul>
{% for choice in form.Field %}
<li>{{ choice.choice_label|safe }}</li>
{% endfor %}
</ul>
<input class="btn btn-dark" type="submit" value="Submit">
</form>
Iterate over the choices for your field and then you can get your customized labels with:
{{ choice.choice_label|safe }}
The safe filter is needed so your HTML is not escaped.