Django在视图中获取自引用ManyToManyField中的相关项目

Question

How do I get all the items associated with a part via the self-referential ManyToManyField? How to I fix my view to get part_list to contain a list of all the parts associated with 'product' and in the order specified by order_by?

# views.py

def productdetail(request, slug):    
    product = get_object_or_404(PartModel, slug=slug)

    part_list = PartModel.objects.all().filter(buildpart__id=product.pk).order_by('family__type')

    return render(request, 'productdetail.html', locals())

Here's the template:

# productdetail.html

    <header>
        <h1>'{{ product.name }}' Detail Page</h1>
    </header>

    <p>{{ product.name }}
    <p>{{ product.slug }}
    <p>{{ product.family }}
    <p>{{ product.family.type }}
    <p>{{ product.family.make }}
    <p>${{ product.price }}
    {% for part in part_items %}
        <p>{{ part.name }}
    {% endfor %}

Notice the PartModel model holding our inventory and its self-referential BuildPart ManyToMany model through the buildpart field:

class PartModel(models.Model):
    family = models.ForeignKey(PartFamily)
    name = models.CharField("Model Name", max_length=50, unique=True)
    buildpart = models.ManyToManyField('self', through='BuildPart',
                                symmetrical=False, related_name='+')

class Build(models.Model):
    build = models.ForeignKey(PartModel, related_name='+')
    part = models.ForeignKey(PartModel, related_name='+')
    quantity = models.PositiveSmallIntegerField(default=1)

    class Meta:
        abstract = True
        unique_together = ('build', 'part')

    def __unicode__(self):
        return self.build.name + ' with ' + str(self.quantity) + ' * ' + \
               self.part.family.make.name + ' ' + self.part.name

class BuildPart(Build):
    pass

    class Meta:
        verbose_name = "Build Part"

To get everything in the right order with the order_by clause we follow the 'family' field to the PartFamily model:

class PartFamily(models.Model):
    make = models.ForeignKey(PartMake)
    type = models.ForeignKey(PartType)
    name = models.CharField("Family Name", max_length=30,
                             unique=True)
    slug = models.SlugField(unique=True)

And lastly, we get to the model with the 'order' field, the one we wish to sort the related items by, PartType:

class PartType(models.Model):
    name = models.CharField("Part Type", max_length=30, unique=True)
    slug = models.SlugField(unique=True)
    order = models.PositiveSmallIntegerField()
    description = models.TextField(blank=True, null=True)

Answer 1

I was able to find an answer to my own question with Roseman's help. The part_list line should be as follows:

# views.py

part_list = product.buildpart.all().order_by('family__type')

Once Roseman pointed out the variable name mismatch I did up the QuerySet as it made the most sense to me, and it works!