Django foreign key drop down

问题

New to Django and Python and I need a little help with a foreign key drop down. Basically, I have a category model and a image model and I want users to be able to choose which category to put the image in. How do I create a drop down for the category in the image form? Are my views and html correct too? I have had a look online but I can't seem to do it myself. I keep getting errors.

Here are my models:

class Images(models.Model):
    image = models.ImageField(upload_to='images', blank=False)
    img_name = models.CharField(max_length=120, blank=True)
    img_date = models.DateTimeField(default=now())
    img_user = models.ForeignKey(User)
    img_cat_id = models.ForeignKey(Categories)

    def __unicode__(self):
        return self.img_name

class Categories(models.Model):
    cat_descr = models.CharField(max_length =120, blank=False)

    def __unicode__(self):
       return self.cat_descr

VIEWS:

@login_required
def upload_images(request):
    context = RequestContext(request)
    context_dict={}

    if request.method == 'POST':  # render the form, and throw it back.
        # take the form data and process it!

        form = UploadImagesForm(request.POST, request.FILES)

        if form.is_valid():
            print 'form is_valid'


            upload_image = form.save(commit=False)
            upload_image.img_user = request.user

            if 'image' in request.FILES:
                upload_image.image  =request.FILES['image']

            upload_image.save()

            return render(request, 'rmb/upload.html', {'upload_image': form})

        else:
            print form.errors

    # Not a HTTP POST, so we render our form using two ModelForm instances.
    # These forms will be blank, ready for user input.
    else:
        form = UploadImagesForm()

        context_dict = {'upload_image': form}
        all_categories = Categories.objects.order_by('-id')
        context_dict['all_categories'] = all_categories
        print context_dict

        return render_to_response('rmb/upload.html', context_dict, context)

FORMS:

class UploadImagesForm(forms.ModelForm):

#cat_list = ModelChoiceField(queryset=Categories.objects.all())

class Meta:
    model = Images
    fields=('image','img_name')

HTML:

{% block body_block %}
    <form id="upload_form" method="post" action="/rmb/upload/"
            enctype="multipart/form-data">

            {% csrf_token %}
             {{ upload_image.as_table }}
            <input type="submit" name="submit" value="Upload" />
     {% for categories in all_categories %}

         <div> {{ categories.id }} </div>
         {{ categories.cat_descr }}
         <input type="submit" name="submit" value="Upload" />
      {% endfor %}


    </form>
{% endblock %}

回答1:

You don't need to insert the HTML for the form manually, just use {{form}} in the template.

{% block body_block %}
    <form id="upload_form" method="post" action="/rmb/upload/"
            enctype="multipart/form-data">

            {% csrf_token %}
            {{ form }}
    </form>
{% endblock %}

By default a ForeignKey will be a select field so you shouldn't need to do much else.

---

As an aside, give your models and fields more appropriate names. We know these are all image fields, because they are on the image and make sure, unless your model is a collection of things, you give it a singular name. Lastly, when using a Foreign Key and item gets an extra field of fieldname_id that is just the ID, whereas fieldname is the property that gives the related item as well.

So instead of:

class Images(models.Model):
    image = models.ImageField(upload_to='images', blank=False)
    img_name = models.CharField(max_length=120, blank=True)
    img_date = models.DateTimeField(default=now())
    img_user = models.ForeignKey(User)
    img_cat_id = models.ForeignKey(Categories)

Use:

class Image(models.Model):
    image = models.ImageField(upload_to='images', blank=False)
    name = models.CharField(max_length=120, blank=True)
    date = models.DateTimeField(default=now())
    user = models.ForeignKey(User)
    category = models.ForeignKey(Categories)

来源：https://stackoverflow.com/questions/29196521/django-foreign-key-drop-down