Combining AJAX with ModelMultipleChoiceField and custom form - ajax

Question

I've been banging my head for a while and could not find a similar issue.
I'll go over my code
Model
class RestauranteMenu(models.Model):
restaurante = models.ForeignKey(RestauranteUser)
name = models.CharField(max_length=60, blank=False)
class OpeningHours(models.Model):
...
restaurante = models.ForeignKey(RestauranteUser)
menu = models.ForeignKey(RestauranteMenu, blank=True, null=True)
...
Form
class MenuForm(ModelForm):
'''
View = menus(request)
Template = pages/menus.html
'''
horario = ModelMultipleChoiceField(queryset=OpeningHours.objects.all())
def save(self, restaurante, horario, commit=True):
#Linking relationship Restaurant x RestaurantMenu
menu = super(MenuForm, self).save(commit=False)
menu.restaurante = restaurante
if commit:
menu.save()
#Linking relationship RestaurantMenu x OpeningHours
horario = OpeningHours.objects.filter(id=horario, restaurante = restaurante).first()
if horario:
horario.menu = menu
horario.save()
return menu
class Meta:
model = RestauranteMenu
exclude = ['restaurante']
view
def menus(request):
#verify if its an update.
instance = request.POST.get('instance')
if instance not in [None, '']:
menu = RestauranteMenu.objects.get(id=instance)
form = MenuForm(request.POST or None, instance=menu, initial={'horario': OpeningHours.objects.filter(restaurante=request.user).values_list('id', flat=True)})
else:
form = MenuForm(request.POST or None, initial={'horario': OpeningHours.objects.filter(restaurante=request.user).values_list('id', flat=True)})
if request.POST:
if form.is_valid():
try:
#When saving, we pass a restaurant reference and OpeningHours reference.
form.save(request.user, form.data.get('horario'))
JS
$(document).on("click", "#sendmenuform", function() {
var horariosId = [];
$('#horario :selected').each(function(i, selected) {
horariosId.push($(selected).val());
});
$.ajax({
type: "POST",
url: "../menus/",
data: {
name : $('[name="name"]').val(),
horario : horariosId,
instance : $('#sendmenuform').attr("data-id"),
csrfmiddlewaretoken: $('[name="csrfmiddlewaretoken"]').val()
},
success : function(data) {
.... process response...
}
});
What's the issue
Based on my models, I want a Menu to have a ManyToOne relationship with OpeningHours, that means that one Menu can be at different OpeningHours.
When I'm submitting my form (via AJAX), I'm not able to populate the field 'horario' inside the form. When instantiating the form, I'm filling the field with a queryset that will filter by that Restaurant.
On the html, I have a select multiple, so that the restaurant is able to link one Menu to several different OpeningHours object.
I don't know how I'm supposed to process the information sent by the AJAX request to the view, specially this ModelMultipleChoiceField. Do I need to override any of the forms method?

Answer 1

ModelMultipleChoiceField expects model objects and not arbitrary strings. Hence using the values_list query set will only land you into trouble. Your form will not validate.
For your use case, use ChoiceFields. You can populate them with a string by overriding your __init__ method. For example, in your Forms.py
horario = ChoiceField(
choices[],)
def __init__(self, *args, **kwargs):
super(MenuForm, self).__init__(*args, **kwargs)
self.fields['horario'].choices = [(x.id, x.modelfieldtodisplay) for x in OpeningHours.objects.all()]
If you want to do this when you post the form or load it do it inside a view that is triggered by a listener for the event. You'll have to write Javascript to handle this similar to this tutorial but this asks you to use ModelChoiceField which I do not recommend for you because it doesn't work gracefully when you're trying to dynamically populate multiple fields and submit the form, validate it and run some operations on the data.
Instead, I implore you to take a look at Dajax and Dajaxice which takes altogether 5 minutes to set up and handles forms and AJAX effortlessly making your job significantly simpler. I do emphasize though, void using ModelChoiceField for you use case. I learnt that the hard way.