Django - dropdown (select widget) in form is not saving data to db

I'm using this form to get a dropdown menu in my html form :

forms.py

class forms_bdc(forms.ModelForm):

    [...]
    bdc_description_1 = forms.ModelChoiceField(required=False,queryset=models_products.objects.values_list('product_denomination', flat=True), widget=forms.Select(attrs={'id': 'editable-select-2','onchange': 'populate_selected_product(this.id)'}),empty_label=None )

models.py

class models_bdc(models.Model):

    [...]
    bdc_description_1 = models.CharField(max_length=50)

But when I save / submit the form, the data are not saving into the database.

If I remove the select widget to a regular forms.charfield, the datas are saving correctly.

So I assume the mistake is the forms.py but I can't see where.

Thanks

Short answer:

# forms.py

class forms_bdc(forms.ModelForm):
        # ...

        bdc_description_1 = forms.ChoiceField(
            required=True,
            choices=(
                ('option value', 'option label'),
            ),
            widget=forms.Select(attrs={'class': 'your-class'}),
            # ...
        )

Long answer:

advise: for django forms, use PascalCase and end the name with "Form" (convention).

#forms.py

from .models import OPTIONS

class BdcForm(forms.ModelForm): 
        # ...

        bdc_description_1 = forms.ChoiceField(
            required=True,
            choices=OPTIONS,
            widget=forms.Select(attrs={'class': 'your-class'}),
            # ...
        )

# models.py

OPTIONS = (
   ('option value', 'option label'),
   # ...
)

you can set expected values in models and just import and reuse anywhere you want.