模板变体标题未显示

Question

我对models.py中的Item类进行了修改，我认为模板语法正确，但是显然有些错误，我无法弄清

这是模特

class Item(models.Model):
    title = models.CharField(max_length=100)
    description = models.TextField()
    price = models.FloatField()
    slug = models.SlugField(unique=True)
    image = models.ImageField(blank=False, upload_to='approved designs')


    def __str__(self):
        return self.title

    class Meta:
        unique_together = ('title', 'slug')

class Variation(models.Model):
    item = models.ForeignKey(Item, on_delete=models.CASCADE)
    title = models.CharField(max_length=120)
    image = models.ImageField(null=True, blank=True)
    price = models.FloatField(null=True, blank=True)

    def __str__(self):
        return self.title

这是模板

                        {% if item.variation_set.all %}
                        <select class='form-control' name='size'>
                            {% for items in item.variation_set.all %}
                            <option value='{item.variation|lower}'>{{title.title|capfirst}}</option>
                            {% endfor %}
                        </select>
                        {% endif %}