django Custom ManyToMany save on model Formset Options

Question

Hello everyone, I have a formset that is setup to use a join table. The join table joins a Recipe table and an Ingredient table and looks like thus

class RecipeIngredient(models.Model): 
    '''intermediate model between Ingredient and recipe.models.recipe 
for many to many''' 
    quantity =  models.IntegerField() 
    measurement = models.CharField(max_length=200) 
    ingredient = models.ForeignKey(Ingredient) 
    preparation = models.CharField(max_length=100, blank=True, 
null=True) 
    recipe    = models.ForeignKey(Recipe) 

I created the formset like so

IngFormSet = inlineformset_factory(Recipe, RecipeIngredient, 
formset=BaseIngFormSet, extra=5) 

The BaseIngFormSet was created to turn the default drop down menu for the ingredient field (many to many with the Ingredient table), into a input box so that I could then later use jquery-autocomplete on the input box. This would save some time from users having to scroll a very long list of ingredients to select from.

class BaseIngFormSet(BaseModelFormSet): 
    def add_fields(self, form, index): 
        super(BaseIngFormSet, self).add_fields(form,index) 
        form.fields["ingredient"] = forms.CharField() 

That part that I am currently stuck on is, when the form is submitted it fails because the ingredient is no longer in instance of the ingredient table

Cannot assign "u'Ground Turkey'": "RecipeIngredient.ingredient" must be a "Ingredient" instance.

I figured I need to take what is typed into the input box, then do a search on it against the Ingredient model something like Ingredient.objects.get(title="blah")

Then somehow set that object to the RecipeIngredient.ingredient in the formset, before the formset is validated. Sadly though I do not know where or how to do this. I tried going into the shell and setting up the formset then doing a dir(formset) on it to see if that would shed any light on my issue but I didn't come up with anything. Does anyone have any suggestions on how to take what is passed in the ingredient input for the formset, and turn that into an object from the Ingredient table? I know at some point a user may type in an ingredient that is not in the database, and I plan on doing a lookup on what is passed, and if it is not found in the database, I would create it and then pass that new object to the formset. Here is what I currently have in my view for this form

from django.shortcuts import render_to_response, get_object_or_404, 
get_list_or_404, redirect 
from django.template import RequestContext 
from django.contrib.auth.decorators import login_required 
from django.forms.models import modelformset_factory, 
inlineformset_factory 
from models import Recipe, RecipeIngredient 
from ingredient.models import Ingredient 
from forms import RecipeForm, BaseIngFormSet 
@login_required 
def recipe(request): 
    IngFormSet = inlineformset_factory(Recipe, RecipeIngredient, 
formset=BaseIngFormSet, extra=5) 
    if request.method=='POST': 
        form = RecipeForm(request.POST, request.FILES) 
        formset = IngFormSet(request.POST) 
        if form.is_valid() and formset: 
            new_recipe = form.save() 
            instances = formset.save(commit=False) 
            for instance in instances: 
                instance.recipe_id = new_recipe.id 
                instance.save() 
            return redirect(new_recipe.get_absolute_url()) 
    else: 
        form = RecipeForm() 
        formset = IngFormSet(queryset=RecipeIngredient.objects.none()) 
    return render_to_response('recipe/recipe_form.html', {'form': 
form, 'formset' : formset,}, context_instance=RequestContext(request)) 

Thanks for any help you can provide.

Answer 1

Have you considered using a widget that doesn't require any later validation hacking. Perhaps something like http://code.google.com/p/django-ajax-selects/ ? If that doesn't fit exactly, take a look at the fields.py file and their custom form fields.