blocks|key|2586048|text|您的外键中添加了on_delete吗？在Django+2.0中，这个参数是必需的。你还可以看到：删除+https://docs.djangoproject.com/en/2.0/howto/upgrade-version/+一个/+https://docs.djangoproject.com/en/2.0/ref/models/fields/#django.db.models.ForeignKey|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|2586049|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.djangoproject.com/en/2.0/ref/models/fields/#django.db.models.ForeignKey.on_delete|1|https://docs.djangoproject.com/en/2.0/howto/upgrade-version/|2|https://docs.djangoproject.com/en/2.0/topics/db/examples/many_to_one/|3|https://docs.djangoproject.com/en/2.0/ref/models/fields/#django.db.models.ForeignKey^0|1C|2|0|1F|1O|1|34|3|2|38|2C|3|0^^$0|@$1|2|3|4|5|6|7|R|8|@]|9|@$A|S|B|T|1|U]|$A|V|B|W|1|X]|$A|Y|B|Z|1|10]|$A|11|B|12|1|13]]|C|$]]|$1|D|3|-4|5|6|7|14|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]|L|$5|G|H|I|C|$J|M]]|N|$5|G|H|I|C|$J|O]]|P|$5|G|H|I|C|$J|Q]]]]

Do you have add on_delete to your FOREIGN KEY? On Django 2.0 this argument is required.
You could see also:
<a href="https://docs.djangoproject.com/en/2.0/ref/models/fields/#django.db.models.ForeignKey.on_delete" rel="nofollow noreferrer">https://docs.djangoproject.com/en/2.0/ref/models/fields/#django.db.models.ForeignKey.on_delete</a>
<a href="https://docs.djangoproject.com/en/2.0/howto/upgrade-version/" rel="nofollow noreferrer">https://docs.djangoproject.com/en/2.0/howto/upgrade-version/</a>
<a href="https://docs.djangoproject.com/en/2.0/topics/db/examples/many_to_one/" rel="nofollow noreferrer">https://docs.djangoproject.com/en/2.0/topics/db/examples/many_to_one/</a>
<a href="https://docs.djangoproject.com/en/2.0/ref/models/fields/#django.db.models.ForeignKey" rel="nofollow noreferrer">https://docs.djangoproject.com/en/2.0/ref/models/fields/#django.db.models.ForeignKey</a>

blocks|key|951488|text|这些文档说明了两件事：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|951489|如果您有ForeignKey约束，则它们现在在数据库级别强制执行。因此，确保您没有违反外键约束。这是引发问题的最可能原因，尽管这意味着您可能已经在其他数据库中看到了这些问题。在代码中寻找这样的模式:在pagetree/+must+s.py中，第810行@classmethod+def+create_from_dict(cls，d)：返回cls.objects.create()+#在d上发生了什么?这肯定会在ForeignKey约束错误中失败，因为PageBlock必须有section，所以如果不首先分配它，就不能调用create。|ordered-list-item|offset|length|style|CODE|951490|如果通过执行原子事务(例如)以延迟提交外键来规避外键约束，则首先需要推迟提交外键。实际上，您的测试数据库应该已经有了，因为每次都会重新构建它。|951491|entityMap^0|0|69|9|6L|7|79|6|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@$E|O|F|P|G|H]|$E|Q|F|R|G|H]|$E|S|F|T|G|H]]|9|@]|A|$]]|$1|I|3|J|5|D|7|U|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|V|8|@]|9|@]|A|$]]]|L|$]]

The documentation says two things:

<ol>
<li>If you have ForeignKey constraints they are now enforced at the database level. So make sure you're not violating a foreign key constraint. That's the most likely cause for your issue, although that would mean you'd have seen these issues with other databases. Look for patterns like this in your code:

<pre><code># in pagetree/models.py, line 810
@classmethod
def create_from_dict(cls, d):
 return cls.objects.create() # what happens to d by the way?
</code></pre>

This will definitely fail with a ForeignKey constraint error since a <code>PageBlock</code> must have <code>section</code>, so you can't call <code>create</code> without first assigning it.</li>
<li>If you circumvent the foreign key constraint by performing an atomic transaction (for example) to defer committing the foreign key, your Foreign Key needs to be INITIALLY DEFERRED. Indeed, your test db should already have that since it's rebuilt every time.</li>
</ol>

blocks|key|2586169|text|同样的错误，我遇到了不同的情况。问题是我使用了相同的模型名和字段名|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2586170|错误代码：|2586171|class+Column(models.Model):
++++...

class+ColumnToDepartment(models.Model):
++++column+=+models.ForeignKey(Column,+on_delete=models.CASCADE)|code-block|syntax|javascript|2586172|解决方案：|2586173|class+Column(models.Model):
++++...

class+ColumnToDepartment(models.Model):
++++referring_column+=+models.ForeignKey(Column,+on_delete=models.CASCADE)|2586174|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Q|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

I met a different situation with the same error. The problem was that I used the same Model name and field name
Incorrect code:
<pre class="lang-py prettyprint-override"><code>class Column(models.Model):
 ...

class ColumnToDepartment(models.Model):
 column = models.ForeignKey(Column, on_delete=models.CASCADE)
</code></pre>
Solution:
<pre class="lang-py prettyprint-override"><code>class Column(models.Model):
 ...

class ColumnToDepartment(models.Model):
 referring_column = models.ForeignKey(Column, on_delete=models.CASCADE)
</code></pre>

blocks|key|951524|text|我刚刚在Django项目上犯了一个错误：sqlite3.IntegrityError:+FOREIGN+KEY+constraint+failed。结果，我删除了一行中的某个迁移文件夹，因此在运行python+manage.py+makemigrations时，它没有拾取我的模型更改。只需确保仍然有一个包含迁移的迁移文件夹。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|951525|entityMap^0|K|1H|2Q|V|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|M|8|@]|D|@]|E|$]]]|G|$]]

I just had this error: <code>sqlite3.IntegrityError: FOREIGN KEY constraint failed</code> on my Django project. Turns out I deleted the migrations folder somewhere along the line so it didn't pick up my model changes when I ran <code>python manage.py makemigrations</code>. Just make sure you still have a migrations folder with migrations in.

blocks|key|2586261|text|还有一件事要检查，在我的例子中，它与我的夹具文件有关。迁移到Django3后重新生成它们解决了我在测试应用程序时遇到的问题。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2586262|./manage.py+dumpdata+app.Model1+app.Model2+--indent=4+>+./app/fixtures/file.json|code-block|syntax|javascript|2586263|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

One more thing to check, in my case it was related to my fixtures files.
Regenerating them after migration to Django3 solved the issue I had while testing my app.

<pre><code>./manage.py dumpdata app.Model1 app.Model2 --indent=4 &gt; ./app/fixtures/file.json
</code></pre>

blocks|key|478846|text|当我在迁移或表格方面遇到困难时，我会这样做，而且它经常会帮助我：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|478847|评论你的麻烦字符串；|ordered-list-item|478848|做python3+manage.py+makemigrations和python3+manage.py+migrate；|offset|length|style|CODE|478849|然后你必须做python3+manage.py+migrate+--fake；|478850|取消对字符串的注释，然后再次执行python3+manage.py+makemigrations和python3+manage.py+migrate。|478851|我希望这对你有帮助|478852|entityMap^0|0|0|1|W|Y|P|0|6|W|0|G|W|1D|P|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$]]|$1|E|3|F|5|D|7|U|8|@$G|V|H|W|I|J]|$G|X|H|Y|I|J]]|9|@]|A|$]]|$1|K|3|L|5|D|7|Z|8|@$G|10|H|11|I|J]]|9|@]|A|$]]|$1|M|3|N|5|D|7|12|8|@$G|13|H|14|I|J]|$G|15|H|16|I|J]]|9|@]|A|$]]|$1|O|3|P|5|6|7|17|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|18|8|@]|9|@]|A|$]]]|R|$]]

When I have trouble with migrations or tables, I do it and it very often helps:
<ol>
<li>Comment your trouble strings;</li>
<li>Do <code>python3 manage.py makemigrations</code> and <code>python3 manage.py migrate</code>;</li>
<li>Then u must do <code>python3 manage.py migrate --fake</code>;</li>
<li>Uncomment your strings and do it again <code>python3 manage.py makemigrations</code> and <code>python3 manage.py migrate</code>.</li>
</ol>
I hope it is useful for u

blocks|key|2586308|text|在我的例子中，我发现我的模型所引用的ForeignKey对象不存在。因此，我将引用的FK对象更改为现有对象。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2586309|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

In my case, I found that the ForeignKey object that my model refers to does not exist.
Therefore, I change the referenced FK object to the existing object.

blocks|key|951631|text|在进行迁移之后，我的问题得到了解决，因为我修改了外键，然后没有应用迁移。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|951632|具体来说，首先我在模型中有以下代码：|951633|class+TeacherRequest(models.Model):
++++requester+=+models.ForeignKey(
++++++++Profile,
++++++++on_delete=models.CASCADE,
++++++++related_name="teacher_request",
++++)

++++class+RequestStatus(models.TextChoices):
++++++++PENDING+=+'1',+_('pending')
++++++++APPROVED+=+'2',+_('approved')
++++++++REJECTED+=+'3',+_('rejected')

++++status+=+models.CharField(
++++++++choices=RequestStatus.choices,
++++++++max_length=1,
++++++++default=RequestStatus.PENDING,
++++)|code-block|syntax|javascript|951634|然后我将外键从Profile更改为User|offset|length|style|CODE|951635|class+TeacherRequest(models.Model):
++++requester+=+models.ForeignKey(
++++++++User,
++++++++on_delete=models.CASCADE,
++++++++related_name="teacher_request",
++++)

++++class+RequestStatus(models.TextChoices):
++++++++PENDING+=+'1',+_('pending')
++++++++APPROVED+=+'2',+_('approved')
++++++++REJECTED+=+'3',+_('rejected')

++++status+=+models.CharField(
++++++++choices=RequestStatus.choices,
++++++++max_length=1,
++++++++default=RequestStatus.PENDING,
++++)|951636|溶液|BOLD|951637|python+manage.py+makemigrations
python+manage.py+migrate|951638|entityMap^0|0|0|0|7|7|H|4|0|0|0|2|0|0^^$0|@$1|2|3|4|5|6|7|X|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Y|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Z|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|10|8|@$K|11|L|12|M|N]|$K|13|L|14|M|N]]|9|@]|A|$]]|$1|O|3|P|5|F|7|15|8|@]|9|@]|A|$G|H]]|$1|Q|3|R|5|6|7|16|8|@$K|17|L|18|M|S]]|9|@]|A|$]]|$1|T|3|U|5|F|7|19|8|@]|9|@]|A|$G|H]]|$1|V|3|-4|5|6|7|1A|8|@]|9|@]|A|$]]]|W|$]]

My problem was solved after doing the migration, because I have altered the foreign key and then didn't apply the migrations.
Specifically, at first I have the following piece of code in models:
<pre><code>class TeacherRequest(models.Model):
 requester = models.ForeignKey(
 Profile,
 on_delete=models.CASCADE,
 related_name=&quot;teacher_request&quot;,
 )

 class RequestStatus(models.TextChoices):
 PENDING = '1', _('pending')
 APPROVED = '2', _('approved')
 REJECTED = '3', _('rejected')

 status = models.CharField(
 choices=RequestStatus.choices,
 max_length=1,
 default=RequestStatus.PENDING,
 )
</code></pre>
Then I have changed the foreign key from <code>Profile</code> to <code>User</code>:
<pre><code>
class TeacherRequest(models.Model):
 requester = models.ForeignKey(
 User,
 on_delete=models.CASCADE,
 related_name=&quot;teacher_request&quot;,
 )

 class RequestStatus(models.TextChoices):
 PENDING = '1', _('pending')
 APPROVED = '2', _('approved')
 REJECTED = '3', _('rejected')

 status = models.CharField(
 choices=RequestStatus.choices,
 max_length=1,
 default=RequestStatus.PENDING,
 )
</code></pre>
Solution
<pre><code>python manage.py makemigrations
python manage.py migrate
</code></pre>

blocks|key|2586346|text|一个原因可能是，当您从数据库中删除一个与外键链接到其他地方的项时，会出现什么情况？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2586347|体育课。当您删除一个有活动书籍的作者时，会发生什么？|2586348|我并不打算进入应用程序的逻辑，但是考虑一下，例如，cascade删除链接到该键的元素。|offset|length|style|CODE|2586349|下面是一个示例，在本例中，我们处理每个“用户”的"post“属性。|2586350|user+=+models.ForeignKey(User,+related_name='posts',+on_delete=models.CASCADE)|code-block|syntax|javascript|2586351|这里有一个仔细的解释，Django+4.0：https://docs.djangoproject.com/en/4.0/ref/models/fields/|2586352|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.djangoproject.com/en/4.0/ref/models/fields/^0|0|0|P|7|0|0|0|M|1K|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|11|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|12|8|@$F|13|G|14|H|I]]|9|@]|A|$]]|$1|J|3|K|5|6|7|15|8|@]|9|@]|A|$]]|$1|L|3|M|5|N|7|16|8|@]|9|@]|A|$O|P]]|$1|Q|3|R|5|6|7|17|8|@]|9|@$F|18|G|19|1|1A]]|A|$]]|$1|S|3|-4|5|6|7|1B|8|@]|9|@]|A|$]]]|T|$U|$5|V|W|X|A|$Y|Z]]]]

A reason could be you miscalculated what happens when you delete an item from the db that is linked with a foreign key to something else, elsewhere.
p.e. what happens when you delete an author that has active books?
I don't meant to enter into the logic of the application, but consider for example to <code>cascade</code> the deletion of the elements linked to that key.
Here is an example, in this case we are dealing with &quot;post&quot; attribute for each &quot;user&quot;
<pre><code>user = models.ForeignKey(User, related_name='posts', on_delete=models.CASCADE)
</code></pre>
Here's a careful explanation, Django 4.0:
<a href="https://docs.djangoproject.com/en/4.0/ref/models/fields/" rel="nofollow noreferrer">https://docs.djangoproject.com/en/4.0/ref/models/fields/</a>

blocks|key|951654|text|错误的原因很可能是由于模型中缺少匹配的Foreignkey元素，以及您试图保存的元素(使用那个外键进行更新)。确保在您的数据和新的数据中都存在外键约束(值)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|951655|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Most probably the cause of the error is the lacking of matching Foreignkey elements in your model and the one your trying to save(update using that foreignkey).
Make sure that the foreignkey constraints(value) are present in both your and the new data

blocks|key|2586378|text|同样的错误，我遇到了不同的情况。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2586379|问题是，我将on_delete属性设置为DO_NOTHING，这最终导致了violating+foreign+key+constraints。|offset|length|style|CODE|2586380|把它设置为SET_NULL，为我修复了它。|2586381|entityMap^0|0|6|9|K|A|11|X|0|5|8|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|M|8|@$D|N|E|O|F|G]|$D|P|E|Q|F|G]|$D|R|E|S|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|T|8|@$D|U|E|V|F|G]]|9|@]|A|$]]|$1|J|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|K|$]]

I met a different situation with the same error.
The problem was that i had my <code>on_delete</code> attributes set to <code>DO_NOTHING</code>, which ended up <code>violating foreign key constraints</code>.
Setting it to <code>SET_NULL</code> fixed it for me.

I'm working on adding Django 2.0 support to the <a href="https://github.com/ccnmtl/django-pagetree" rel="noreferrer">django-pagetree</a> library. During automated testing, using an sqlite in-memory database, I'm getting a bunch of errors like this:

<pre><code> File "/home/nnyby/src/django-pagetree/pagetree/tests/test_models.py", line 638, in setUp
 'children': [],
 File "/home/nnyby/src/django-pagetree/pagetree/models.py", line 586, in add_child_section_from_dict

...

 File "/home/nnyby/src/django-pagetree/venv/lib/python3.5/site-packages/django/db/backends/base/base.py", line 239, in _commit
 return self.connection.commit()
django.db.utils.IntegrityError: FOREIGN KEY constraint failed
</code></pre>

This is noted in the Django 2.0 release notes: <a href="https://docs.djangoproject.com/en/2.0/releases/2.0/#foreign-key-constraints-are-now-enabled-on-sqlite" rel="noreferrer">https://docs.djangoproject.com/en/2.0/releases/2.0/#foreign-key-constraints-are-now-enabled-on-sqlite</a>

From that description, which I don't fully understand, this shouldn't apply for test databases that aren't persistent, right? Wouldn't my sqlite test db get created with the appropriate options when using Django 2.0?

The app settings I'm using for testing are here: <a href="https://github.com/ccnmtl/django-pagetree/blob/master/runtests.py" rel="noreferrer">https://github.com/ccnmtl/django-pagetree/blob/master/runtests.py</a>

Django 2.0: sqlite IntegrityError: FOREIGN KEY constraint failed

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我正在将Django 2.0支持添加到库中。在自动测试过程中，使用内存中的sqlite数据库，我得到了一些错误，如下所示：  File "/home/nnyby/src/django-pagetree/pagetree/tests/test_models.py", line 638, in setUp    'chil...

问Django 2.0: sqlite :外键约束失败
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