Django | 在同一个模板上多次使用同一个表单

Question

I have a project with a model called "List," and a model called "ListItem." There are multiple list items to each list. Here's what I'd like to do. I'd like the user to be able to create a new list with as many items as they deem necessary on one form.

Here's the logic I have so far:

models.py:

class List(models.Model):
    team = models.ForeignKey(Team, on_delete=models.CASCADE)
    name = models.CharField(max_length=50)

    def __str__(self):
        return self.name


class ListItem(models.Model):
    team_list = models.ForeignKey(List, on_delete=models.CASCADE)
    content = models.TextField()
    index = models.IntegerField()

    def __str__(self):
        return f"{self.team_list} [{self.index}]"

forms.py:

class NewListForm(forms.ModelForm):
    name = forms.CharField(max_length=50, label='Card Name')
    team = forms.ModelChoiceField(queryset=models.Team.objects.all())

    class Meta:
        model = models.List
        fields = ['name', 'team']


class NewListItemForm(forms.ModelForm):
    content = forms.CharField(widget=forms.Textarea,
                              label='Item', required=True)

    class Meta:
        model = models.ListItem
        fields = ['content']

views.py:

def new_list(request):
    context = {
        'title': 'New List',
        'list_form': NewListForm,
        'list_item_form': NewListItemForm,
    }
    if request.method == 'POST':
        list_form = NewListForm(request.POST)
        list_item_form = NewListItemForm(request.POST)
        if list_form.is_valid() and list_item_form.is_valid():
            list_instance = list_form.save()
            list_item_instance = list_item_form.save(commit=False)
            list_item_instance.team_list = list_instance
            list_item_instance.index = 1
            list_item_instance.save()
            messages.success(request, "List has been created!")
            return redirect('home')
        else:
            messages.error(request, "That list name is already taken")
    return render(request, 'lists/new_list.html', context)

This works for creating 1 list and just 1 item. Ultimately, I'd like the user to be able to add as many additional list item forms as is necessary AND have the "index" field of each item on that list increment by 1 with each new list item instance.

Is there some way to loop through each instance of a repeated form and save a unique instance in my db an indefinite number of times?

Answer 1

I don't think you need to increment the index yourself, django should increment it automatically. I used formset_factory and javascript on my template to have the ability to add fields to the form dynamically. I am not very familiar with django or javascript (I'm very early in the learning process), but this is how I got it to work in my case:

models.py

class Instructors(models.Model):
    instructors = models.CharField(max_length=60)
    injury = models.ForeignKey("Injury", on_delete=models.CASCADE)

forms.py

class InstructorForm(forms.Form):
    instructor = forms.CharField(max_length=60, required=False)


InstructorFormset = formset_factory(InstructorForm, extra=1)

views.py (relevant section)

...
formset = InstructorFormset(request.POST)
if formset.is_valid()
    for form in formset:
        if form.cleaned_data:
            instructor = Instructors(
                instructors=form.cleaned_data["instructor"],
                injury=injury,
            )
            instructor.save()
...
context = {"formset":formset}

template.html

{{ formset.management_form }}
    {% for form in formset %}
    <div class="row form-row spacer">
        {{ form.instructor }}
        <div class="input-group-append">
...
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
<script type='text/javascript'>
function updateElementIndex(el, prefix, ndx) {
    var id_regex = new RegExp('(' + prefix + '-\\d+)');
    var replacement = prefix + '-' + ndx;
    if ($(el).attr("for")) $(el).attr("for", $(el).attr("for").replace(id_regex, replacement));
    if (el.id) el.id = el.id.replace(id_regex, replacement);
    if (el.name) el.name = el.name.replace(id_regex, replacement);
}
function cloneMore(selector, prefix) {
    var newElement = $(selector).clone(true);
    console.log(newElement);
    var total = $('#id_' + prefix + '-TOTAL_FORMS').val();
    newElement.find(':input:not([type=button]):not([type=submit]):not([type=reset])').each(function() {
        var name = $(this).attr('name');
        if (name != undefined) {
            console.log(name);
            console.log(total);
            var name = name.replace('-' + (total-1) + '-', '-' + total + '-');
            console.log("next");
        };
        var id = 'id_' + name;
        $(this).attr({'name': name, 'id': id}).val('').removeAttr('checked');
    });
    newElement.find('label').each(function() {
        var forValue = $(this).attr('for');
        if (forValue) {
          forValue = forValue.replace('-' + (total-1) + '-', '-' + total + '-');
          $(this).attr({'for': forValue});
        }
    });
    total++;
    $('#id_' + prefix + '-TOTAL_FORMS').val(total);
    $(selector).after(newElement);
    var conditionRow = $('.form-row:not(:last)');
    conditionRow.find('.btn.add-form-row')
    .removeClass('btn-success').addClass('btn-danger')
    .removeClass('add-form-row').addClass('remove-form-row')
    .html('-');
    return false;
}
function deleteForm(prefix, btn) {
    var total = parseInt($('#id_' + prefix + '-TOTAL_FORMS').val());
    if (total > 1){
        btn.closest('.form-row').remove();
        var forms = $('.form-row');
        $('#id_' + prefix + '-TOTAL_FORMS').val(forms.length);
        for (var i=0, formCount=forms.length; i<formCount; i++) {
            $(forms.get(i)).find(':input').each(function() {
                updateElementIndex(this, prefix, i);
            });
        }
    }
    return false;
}
$(document).on('click', '.add-form-row', function(e){
    e.preventDefault();
    cloneMore('.form-row:last', 'form');
    return false;
});
$(document).on('click', '.remove-form-row', function(e){
    e.preventDefault();
    deleteForm('form', $(this));
    return false;
});
</script>

I don't remember where I got the js code, but I did not write it and can't take credit for it. Hopefully you have a better understanding than I do, but it works for me as is.