django中的Slug错误

Question

我是django的新手，目前正在学习基础知识。然而，我坚持与弹头模块。

希望能找到解决办法。提前谢谢。

运行迁移命令时

python manage.py makemigrations rango
python manage.py migrate

我一直得到这个错误:

django.db.utils.IntegrityError: UNIQUE constraint failed: rango_category__new.slug

Models.py文件

from django.db import models
from django.template.defaultfilters import slugify
class Category(models.Model):
    name = models.CharField(max_length=128, unique=True)
    views = models.IntegerField(default=0)
    likes = models.IntegerField(default=0)
    slug = models.SlugField(unique=True)
    def save(self, *args, **kwargs):
        self.slug = slugify(self.name)
        super(Category, self).save(*args, **kwargs)
    def __unicode__(self):
        return self.name

class Page(models.Model):
    category = models.ForeignKey(Category)
    title = models.CharField(max_length=128)
    url = models.URLField()
    views = models.IntegerField(default=0)
    def __unicode__(self):
        return self.title

教程说因为我们没有为这个段鼻涕虫提供默认值，而且我们已经在模型中有了现有的数据，那么migrate命令将给你两个选项。选择提供默认值的选项，并输入"。别担心，这将很快得到更新。现在重新运行"populate.py"脚本。由于为每个Category调用了save方法，因此将执行重写的save方法，从而更新slug字段。运行服务器，并通过管理界面检查模型中的数据。"(教程链接见底部第三点)

populate.py文件

import os
os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'kiran_blog_project.settings')
import django
django.setup()
from exodus.models import Category, Page

def populate():
    python_cat = add_cat('Python',128,64)
    add_page(cat=python_cat,
        title="Official Python Tutorial",
        url="http://docs.python.org/2/tutorial/",views=20)
    add_page(cat=python_cat,
        title="How to Think like a Computer Scientist",
        url="http://www.greenteapress.com/thinkpython/", views=19)
    add_page(cat=python_cat,
        title="Learn Python in 10 Minutes",
        url="http://www.korokithakis.net/tutorials/python/",views=17)
    django_cat = add_cat("Django",64,32)
    add_page(cat=django_cat,
    title="Official Django Tutorial",
    url="https://docs.djangoproject.com/en/1.5/intro/tutorial01/",views=30)
    add_page(cat=django_cat,
        title="Django Rocks",
        url="http://www.djangorocks.com/",views=21)
    add_page(cat=django_cat,
        title="How to Tango with Django",
        url="http://www.tangowithdjango.com/",views=50)
    frame_cat = add_cat("Other Frameworks",32,16)
    add_page(cat=frame_cat,
        title="Bottle",
        url="http://bottlepy.org/docs/dev/",views=13)
    add_page(cat=frame_cat,
        title="Flask",
        url="http://flask.pocoo.org",views=16)
    # Print out what we have added to the user.
    for c in Category.objects.all():
        for p in Page.objects.filter(category=c):
            print "- {0} - {1}".format(str(c), str(p))
def add_page(cat, title, url, views):
    p = Page.objects.get_or_create(category=cat, title=title)[0]
    p.url=url
    p.views=views
    p.save()
    return p
def add_cat(name,views,likes):
    c = Category.objects.get_or_create(name=name)[0]
    c.views=views
    c.likes=likes
    c.save()
    return c
# Start execution here!
if __name__ == '__main__':
    print "Starting  population script..."
    populate()

我的问题是，

1。在选择提供默认值的选项之后我应该输入什么值?

2。指令还指出，我需要运行"populate.py"文件。但在运行此文件之前，我认为我需要包含slug字段。那么，有人能在"populate.py"字段中指定更改吗?

3。我的django教程链接

4。对于相同的查询，我甚至尝试了使用uuid的答案，但没有成功。

Answer 1

您必须修改您的迁移文件以避免唯一的约束。根据这个说明，修改您的最后一个迁移文件(它将slug字段添加到模型中)，如下所示:

型号:slug = models.SlugField(unique=True, default=uuid.uuid1)

迁移文件:(即:0004_category_slug.py)

class Migration(migrations.Migration):
    dependencies = [
        ('yourproject', '0003_remove_category_slug'),
    ]
    def gen_slug(apps, schema_editor):
        for row in Category.objects.all():
            row.slug = slugify(row.name)
            row.save()
    operations = [
        migrations.AddField(
            model_name='category',
            name='slug',
            field=models.SlugField(default=uuid.uuid4),
            preserve_default=True,
        ),
        migrations.RunPython(gen_slug),
        migrations.AlterField(
            model_name='category',
            name='slug',
            field=models.SlugField(default=uuid.uuid4, unique=True),
        ),
    ]