Question

I have a form in my website, which is the same for three tables (Homework, Class, Random)
So basically I want to make a ChoiceField on the top of the form, to let user choose where to upload file.

I was thinking, because these tables have common abstract class, may be I can choose it from there somehow. But can not figure out how.

Or may be there is much better solution for this.

just in case this is my code:

#models.py
class FileDescription(models.Model):

    class Meta:
        abstract = True;
        ordering = ['file_creation_time']

    subject = models.ForeignKey('Subjects', null=True, blank=True, primary_key=True)
    subject_name = models.CharField(max_length=100)
    file_uploaded_by = models.CharField(max_length=100)
    file_name = models.CharField(max_length=100)
    file_description = models.TextField()
    file_creation_time = models.DateTimeField(auto_now_add=True)

    def __unicode__(self):
        return u'%s' % (self.file_name)

#template
<ul id="tabs">
        <li><a href="#homework">Homework</a></li>
        <li><a href="#class-papers">Class Papers</a></li>
        <li><a href="#random-papers">Random Papers</a></li>
    </ul>

    <div id="homework" class="tab-section">
        <h2>Homework</h2>
        <p>This section contains Homework</p>

            {% if homework_files %}
                <ul>
                    {% for file in homework_files %}
                        <li>{{ file.file_name }}
                    {% endfor %}
                </ul>
            {% endif %}
    </div>

#forms.py
class Homework_Content_Form(forms.ModelForm):
    class Meta:
        model=Homework_Content
        exclude=('subject', 
                 'subject_name',
                 'file_creation_time',
                 'file_uploaded_by',
                 )

Answer 1

Method 1: Separate Forms

class GenericContentForm(forms.ModelForm):
     class Meta:
         exclude = ('subject', 'subject_name', 'file_creation_time', 'file_uploaded_by')

     TYPE_CHOICES = (
         ('homework', 'Homework'),
         ('class', 'Class Paper'),
         ('random', 'Random Paper'),
     )

     type = forms.ChoiceField(choices=TYPE_CHOICES)

class HomeworkForm(GenericContentForm):
     class Meta(GenericContentForm.Meta):
         model = Homework

class ClassPaperForm(GenericContentForm):
     class Meta(GenericContentForm.Meta):
         model = ClassPaper

class RandomPaperForm(GenericContentForm):
     class Meta(GenericContentForm.Meta):
         model = RandomPaper

Then in your view you just pick one to start with, and when you have the POST data, you can instantiate a different one instead:

def my_view(request):
    if request.method == 'POST':
        type = request.POST.get('type')
        if type == 'homework':
            form = HomeworkForm(request.POST)
        elif type == 'class':
            form = ClassPaperForm(request.POST)
        elif type == 'random':
            form = RandomPaperForm(request.POST)

    else:
        form = HomeworkForm()

    ...

Method 2: Use Proxy Models

Since these three models all share the same data, having three separate tables is redundant. Instead of FileDescription being abstract, make it just a normal standard model, and add a field to it for type, with choices of “Homework”, “Class Paper” and “Random Paper”. Then create proxy models for each:

class HomeworkManager(models.Manager):
    def get_query_set(self, *args, **kwargs):
        qs = super(HomeworkManager, self).get_query_set(*args, **kwargs)
        return qs.filter(type='homework')

class Homework(FileDescription):
    class Meta:
        proxy = True

    objects = HomeworkManager()

    def save(self, *args, **kwargs):
        self.type = 'homework'
        super(Homework, self).save(*args, **kwargs)

Then, you just need one form for FileDescription and when the user’s choice for the “type” will be saved. You can then access anything set as type “homework” with the standard Homework.objects.all().