Django forms - create a form for each object in model, and then save to the corresponding PK

问题

I'm new to django (and programming in general). Sorry if I used the wrong vocabulary (and please correct me). This is what i'm trying to do:

I have this model:

Class A(models.Model):
    name = models.CharField(max_length=100, null=True, default='John')

    first_number = models.FloatField(blank=True, default=1)

    second_number = models.FloatField(blank=True, default=2)

    third_number = models.FloatField(blank=True, default=3)

And I have this form:

class Numbers(ModelForm):
    class Meta:
        model = A

        fields = ['first_number', 'second_number']

In my template, I created a for for x in a (given that 'a' is A.objects.all()):

{% for x in a %}
{{form}}
{% endfor %}

When I submit the form, though, I cant get the corresponding numbers. I only saves the last number I enter in both 'first_number' and 'second_number' for the both objects that I created.

How can I save the correct values?

回答1:

When you render forms like this in a loop you get a number of identical forms in your page code with a number of inputs with the same "name" attributes. If you include your loop into a single tag your POST request will always send the last values found inside form for each field name.

<form>
    <input name="first_number" value="1">
    <input name="first_number" value="2">
    <input name="first_number" value="3">
</form>

POST dict will contain {"first_number": "3"}

This will render each of your form but you'll be able to submit only one at once:

{% for x in a %}
    <form>
         {{form}}
    </form>
{% endfor %}

If you want to deal with identical data and send it as a list you'll need to use "prefix" arg in your form instances:

a = [Numbers(instance=x, prefix=str(x.pk)) for x in A.objects.all()]

#and then in a view
a = [Numbers(request.POST, instance=x, prefix=str(x.pk)) 
     for x in A.objects.all()]

if all([f.is_valid() for f in a]):
    for f in a:
        f.save(commit=True)

This is a slightly primitive example. In real life you would probably like to add some hidden field to your form to pass a list of ids (as json maybe) to a form, and then iterate over it instead of all instances in your db

来源：https://stackoverflow.com/questions/64030787/django-forms-create-a-form-for-each-object-in-model-and-then-save-to-the-corr