如何根据以前的用户选择在 Django 中预填充（多个）ChoiceField

Question

我设法将用户选择的类别存储并更新到数据库中。现在我想在用户再次查询表单时使用此选择预填充 MultipleChoiceSelect。

所以我当前的表单将始终 return 所有可用类别。我如何将用户的个人选择应用于此，以便在 DOM?

中预先选择他的最后一个选择

# Models

class UserCategoryFilter(models.Model):
    """
    Saves the selected category filter by a user
    """
    user = models.ForeignKey(Account, on_delete=models.CASCADE)
    categories_selected = models.CharField(max_length=2000)


class Category(models.Model):
    """
    Model to store all available categories
    """
    poller_category = models.CharField(max_length=30)

# Form

class SelectCategoryForm(forms.Form):
    choices = forms.ModelMultipleChoiceField(queryset=Category.objects.all(),
                                             widget=forms.CheckboxSelectMultiple)

# View

@require_POST
def save_category_filter(request):

    [..]

        # Get the form instance
        filter_form = SelectCategoryForm(request.POST)

        # Form validation
        if filter_form.is_valid():


            # Get the cleaned data
            selection = filter_form.clean()

            # Check if user already has a filter instance
            instance_exists = UserCategoryFilter.objects.filter(user=request.user)

            # If not create, else update
            if not instance_exists:
                filter_instance = UserCategoryFilter(user=request.user,
                                                     categories_selected=selection)
                filter_instance.save()
            else:
                # Update existing instance
                UserCategoryFilter.objects.filter(user=request.user).update(categories_selected=selection)
                pass
        [..]

这就是用户选择当前保存在 categories_selected 中的方式：

{'choices': <QuerySet [<Category: Sports>, <Category: Lifestyle>]>}

Answer 1

您可以在创建表单时设置选项字段的初始值：

filter_form = SelectCategoryForm(
    request.POST, 
    initial={'choices': Category.objects.filter(<get_user's_category_here>)}
)

您没有共享模型，因此构建查询有点棘手，但只需更改过滤器即可获取用户的当前类别。

Answer 2

This is how the selection of the user is currently saved in categories_selected:

{'choices': <QuerySet [<Category: Sports>, <Category: Lifestyle>]>}

这不是一个友好的数据结构。相反，让我们做 ["Sports", "Lifestyle"].

# Get the cleaned data
selection = filter_form.clean()
selection = json.dumps([c.poller_category for c in selection['choices']])  # Add this

现在，我们可以json.loads选择和.filter(poller_category__in=selection)。

然后，我们将 SelectCategoryForm(initial={'choices': choices}) 中的初始选择传递给

。

@require_GET
def select_category(request):
    choices = ()
    user_category_filter_queryset = UserCategoryFilter.objects.filter(user=request.user)
    selection = user_category_filter_queryset.values_list('categories_selected', flat=True).first()
    if selection:
        try:
            selection = json.loads(selection)
        except JSONDecodeError:
            pass
        if selection:
            choices = Category.objects.filter(poller_category__in=selection)
    form = SelectCategoryForm(initial={
        'choices': choices,
    })
    return render(request, 'select-category.html', {'form': form})

如何根据以前的用户选择在 Django 中预填充（多个）ChoiceField

How to pre-populate (Multiple)ChoiceField in Django based on previous user selection

django

django-forms

django-queryset