Question

I’m trying to loop through form fields and store them in the database. The problem is that it’s always only the last field that gets stored. The previous ones are “skipped”. Can I process the forms in Django in the following way?

models.py:

class Category(models.Model):
    name = models.CharField(max_length=30, unique=True)
    user = models.ForeignKey(User, blank=True, null=True)

    class Meta:
        verbose_name_plural = "Ingredience Categories"

    def __unicode__(self):
        return self.name

forms.py

class CategoryForm(ModelForm):
    class Meta:
        model = Category
        fields = ('name',)

home.html template (I’m buildin my form “manually” because I want to be able to dynamically add more input fields via jQuery):

<h3>Insert New Categories</h3>
<form action="/" method="post" id="ingr-cat-form">{% csrf_token %}
    <p><label for="id_0-name">Name:</label> <input type="text" maxlength="30" name="name" id="id_0-name"></p>
    <p><label for="id_1-name">Name:</label> <input type="text" maxlength="30" name="name" id="id_1-name"></p>
    <p><label for="id_2-name">Name:</label> <input type="text" maxlength="30" name="name" id="id_2-name"></p>
    <input type="submit" name="ingrCatForm" value="Save" /> 
</form> 

views.py:

def home(request):
    if request.method == 'POST':
        catform = CategoryForm(request.POST, instance=Category()) # store bounded form to catform
        catformInstance = catform.save(commit = False)  # create instance for further modification, don't commit yet
        catformNames = request.POST.getlist('name') # get a list of input values whose element name is "name"
        for name in catformNames: # loop through all name elements
            catformInstance.name = name # modify form instance; insert current name
            catformInstance.save() # save the instance to the database
        return HttpResponseRedirect('')
    else:
        catform = CategoryForm(instance=Category())

    context = {'catform': catform}
    return render_to_response('home.html', context, context_instance=RequestContext(request))

Test Case Steps:

1. Insert the following values in the 3 input fields: value1, value2, value3
2. Press the submit button

Expected Result:

• all 3 values are stored in the database

Actual Result:

• only the last value (value3) is stored in the database

Answer 1

You create only one instance of catformInstance, then alter it’s value each time in the loop. You are updating one row in the database instead of creating a new row each time.

Do this instead:

    for name in request.POST.getlist('name'):
        catform = CategoryForm({'name': name}, instance=Category())
        catform.save()

Note that we pass in each name explicitly instead of the whole set of POST values; in that case it’ll just grab the last name from the name list, then fail during the next iteration as name is no longer available from the request.