django-ajax-selects app: How do I create a new object when there isn't already one in the database?

问题

I'm using django-ajax-selects, which is a freely available django app providing jquery autocomplete functionality.

I've got it working - i.e. it is autocompleting the form fields I want it to. But I have a problem... I'm using it in a ModelForm which adds Partnership objects to the database:

class Skater(models.Model):
    name = models.CharField(max_length=64)
    surname = models.CharField(max_length=64)
    gender = models.CharField(max_length=1, choices=GENDER_CHOICES)

class Partnership(models.Model):
    female_partner = models.ForeignKey(Skater, limit_choices_to = {'gender': FEMALE}, related_name='female_partner_set')
    male_partner = models.ForeignKey(Skater, limit_choices_to = {'gender': MALE}, related_name='male_partner_set')

I want the user to be able to put in a name and surname into the female_partner and male_partner field even if a Skater object like that doesn't exist and I want that object created. How do I go about doing this? I cannot put the code in the form's save method because the field won't validate (it's not a valid Skater).

EDIT 1: Adding in more code...

The form:

class PartnershipAddForm(forms.ModelForm):
    female_partner = AutoCompleteSelectField('female_skater',required=True)
    male_partner = AutoCompleteSelectField('male_skater',required=True)

    class Meta:
        model = Partnership

settings.py:

AJAX_LOOKUP_CHANNELS = {
    'female_skater' : ('skaters.lookups', 'FemaleLookup'),
    'male_skater' : ('skaters.lookups', 'MaleLookup'),
}

lookups.py (MaleLookup is the same except that gender=MALE):

class FemaleLookup(object):

    def get_query(self,q,request):
        """ return a query set.  you also have access to request.user if needed """
        return Skater.objects.filter(Q(gender=FEMALE) & (Q(name__istartswith=q) | Q(surname__istartswith=q)))

    def format_item(self,skater):
        """ simple display of an object when it is displayed in the list of selected objects """
        return unicode(skater)

    def format_result(self,skater):
        """ a more verbose display, used in the search results display.  may contain html and multi-lines """
        return "%s<br/>" % unicode(skater)

    def get_objects(self,ids):
        """ given a list of ids, return the objects ordered as you would like them on the admin page.
            this is for displaying the currently selected items (in the case of a ManyToMany field)
        """
        return Skater.objects.filter(pk__in=ids).order_by('name','surname')

回答1:

AutoCompleteSelectField holds the id of the object rather than the text, which is why I had the "required" error all along (and why Daniel's solution doesn't work). The value variable was empty as a Skater that doesn't exist doesn't have an id.

I'm not sure this is the best way of doing this, but I ended up using AutoCompleteField instead of AutoCompleteSelectField. AutoCompleteField holds text, but it doesn't create a Skater object for me.

The code:

class PartnershipAddForm(forms.ModelForm):
    female_partner = AutoCompleteField('female_skater',required=True)
    male_partner = AutoCompleteField('male_skater',required=True)

    class Meta:
        model = Partnership

    def save(self):
        partners = [self.cleaned_data['female_partner'],
                    self.cleaned_data['male_partner']]
        name = ['','']
        surname = ['','']
        for i in [0,1]:
            name[i],surname[i] = get_name_surname(partners[i])
        partners = [None,None]
        partners_created = [None,None]
        gender = [FEMALE,MALE]
        for i in [0,1]:        
            partners[i],partners_created[i] = Skater.objects.get_or_create(
                                            name=name[i],
                                            surname=surname[i],
                                            gender=gender[i]
                                        )

         partnership, created = Partnership.objects.get_or_create(
                                    female_partner=partners[0],
                                    male_partner=partners[1],
                                )
         return partnership

回答2:

It looks like you need to subclass AutoCompleteSelectField from ajax-selects and override its clean method.

def clean(self, value):
    if value:
        lookup = get_lookup(self.channel)
        objs = lookup.get_objects( [value] )
        if objs:
            return objs[0]
        else:
            firstname, surname = value.split(" ")
            gender = self.channel.split("_")[0]
            new_skater = Skater(name=firstname, surname=surname, gender=gender)
            return new_skater
    else:
        if self.required:
            raise forms.ValidationError(self.error_messages['required'])
        return None

回答3:

Could we see what your form looks like? I think you need to so something like override the save() method in your ModelForm, so it saves the female_partner and male_partner first, then saves the form instance (aka Parntership instance).

来源：https://stackoverflow.com/questions/2128947/django-ajax-selects-app-how-do-i-create-a-new-object-when-there-isnt-already-o