Django-将表单中的数据保存到数据库中

Question

I have just finished a Django tutorial for an email sign up form and I am trying to tweak some parts of the code to match my needs (adding an additional field to the sign up form)

Based on the tutorial I created an email signup Model form:

class JoinForm(forms.ModelForm):
    class Meta:
        model = Join
        fields = ["email","wunschrad"]

and I altered it a little bit by adding the wunschrad field

then I updated my model to include wunschrad and synced the database with south, all working out fine. below my model:

class Join(models.Model):
    email = models.EmailField()
    wunschrad = models.CharField(max_length=120)
    friend = models.ForeignKey("self", related_name='referral', null=True, blank=True)
    ref_id = models.CharField(max_length=120, default='ABC', unique=True)
    ip_address = models.CharField(max_length=120, default='ABC')
    timestamp = models.DateTimeField(auto_now_add = True, auto_now = False)
    updated = models.DateTimeField(auto_now_add = False, auto_now = True)

    def __unicode__(self):
        return "%s" % (self.email)

    class Meta:
        unique_together = ("email", "ref_id",)

Where I ran into problems is how do I adopt my view to reflect this change. Here is what I did (my changes highlighted in comments)

def home(request):
    try:
        join_id = request.session['join_id_ref']
        obj = Join.objects.get(id=join_id)
    except:
        obj = None

    form = JoinForm(request.POST or None)
    if form.is_valid():
        new_join = form.save(commit=False)
        email = form.cleaned_data['email']
        wunschrad = form.cleaned_data['wunschrad'] #I ADDED THIS
        new_join_old, created = Join.objects.get_or_create(email=email, wunschrad=wunschrad) # I ADDED WUNSCHRAD HERE
        if created:
            new_join_old.ref_id = get_ref_id()
            if not obj == None:
                new_join_old.friend = obj
            new_join_old.ip_address = get_ip(request)
            new_join_old.save()

        return HttpResponseRedirect("/%s" %(new_join_old.ref_id))


    context = {"form": form}
    template = "home.html"
    return render(request, template, context)

My question/ problem is the following: This code snippet works but if a user signs up with the same email address and chooses once the first option of wunschrad and the second time the second option (for clarification: wunschrad is a drop-down list with two options) Django saves two versions in the database, like shown here: Django Admin Screenshot

Does anyone have an idea how to alter the code to save it only once per user?

many many thanks in advance for the help!

Answer 1

So your problem here is by adding wunschrad to get_or_create you are telling Django to look for an entry in the database that has both of those values instead of just the email. Changing it to this should fix it:

new_join_old, created = Join.objects.get_or_create(email=email)
new_join_old.wunschrad = wunschrad
new_join_old.save()

This will make sure it only creates a new object if the email isn't in the database already.

As a side note if you want your email to be unique and raise an error if you try to save another entry with the same email add unique=True to models.EmailField() like:

models.EmailField(unique=True)