django中的Slug错误

Question

我是 django 新手，目前正在学习基础知识。但是，我坚持使用 slug 模块。

希望能找到解决办法。提前致谢。

运行迁移命令时

python manage.py makemigrations rango
python manage.py migrate

我不断收到此错误：

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 “由于我们没有为 slug 提供默认值，并且模型中已经存在数据，因此 migrate 命令会给你两个选项。选择提供默认值的选项，然后输入''。不要担心这会很快就会更新。现在重新运行你的“populate.py”脚本。由于每个类别都调用了 save 方法，因此将执行覆盖的 save 方法，更新 slug 字段。运行服务器，并检查模型中的数据通过管理界面。” （教程的链接在底部的第3点中提到）

填充.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()

所以我的问题是，

1.选择选项后提供默认值 我应该输入什么值？

2.Also 指令指出，我需要运行“populate.py”文件。但是在运行这个文件之前，我想我需要包含 slug 字段。那么有人可以在“populate.py”字段中指定更改吗？

3.my django tutorial link

4.Solution to this same query, I even tried out the answer using uuid but did not work out.

Answer 1

您必须更改您的迁移文件以避免独特的约束。根据这个instruction，像这样修改你的最后一个迁移文件（将 slug 字段添加到模型中）：

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),
        ),
    ]