I have a model:

class Cost(models.Model):
    project = models.ForeignKey(Project)
    cost = models.FloatField()
    date = models.DateField()

For the model I created a class form:

class CostForm(ModelForm):
    class Meta:
        model = Cost
fields = ['date', 'cost']

view.py:

def cost(request, offset):
    if request.method == 'POST':
        #HOW save data in DB?
        return HttpResponseRedirect('/')
    else:
        form = CostForm()

In the template file determined:

<form action="/cost/{{ project }}/" method="post" accept-charset="utf-8">
    <label for="date">Date:</label><input type="text" name="date" value={{ current_date }} id="date" />
    <label for="cost">Cost:</label><input type="text" name="cost" value="0" id="cost" />
    <p><input type="submit" value="Add"></p>
</form>

How save data from form in DB?
P.S. offset = project name
Model:

class Project(models.Model):
    title = models.CharField(max_length=150)
    url = models.URLField()
    manager = models.ForeignKey(User)
    timestamp = models.DateTimeField()

I tried to write:

def cost(request, offset):
    if request.method == 'POST':
        form = CostForm(request.POST)
        if form.is_valid():
            instance = form.save(commit=False)
            instance.project = Project.objects.filter(title=offset)
            instance.date = request.date
            instance.cost = request.cost
            instance.save()
        return HttpResponseRedirect('/')
    else:
        form = CostForm()

But it does not work :(