Django测试不会引发CharField的完整性错误 [英] Django tests don't raise integrity error for CharField
问题描述
如果有以下Django（1.4）模型：
If have the following Django (1.4) model:
from django.db import models
class SimpleModel(models.Model):
name = models.CharField(max_length=100)
这个简单的测试：
from django.test import TestCase
from models import SimpleModel
from django.db import IntegrityError
class SimpleTest(TestCase):
def test_integrity_error(self):
with self.assertRaises(IntegrityError):
m = SimpleModel()
m.save()
作为数据库，使用sqlite3数据库。如果我现在使用 python manage.py test< appname> 运行测试，则测试失败， AssertionError：IntegrityError not raise 。
As database a sqlite3 database is used. If I now run the tests with python manage.py test <appname> the test fails with AssertionError: IntegrityError not raised.
问题是：为什么？
据我所知（或者想了解）Django的默认值为 blank = False 和 null = False 所以我会假设保存一个默认值的模型实例（我认为一个CharField应该是一个空字符串）肯定会失败！那么为什么不这样呢？
As far as I understand (or thought to understand) Django the default values for Fields are blank=False and null=False so I would assume that saving an model instance with the default value (which I think for a CharField should be an empty string) should certainly fail! So, why doesn't this happen?
推荐答案
Django从来没有为空的 CharField 或 TextField 类型。它存储一个空字符串（''）。所以这就是为什么你没有得到 IntegrityError for null = False 。
Django never stores NULL for empty CharField or TextField types. It stores an empty string (''). So that's why you don't get an IntegrityError for null=False.
对于 blank = False ，只影响表单。它只是使该表单设置为 required = True ，因此除非它有一个值，否则它将不会被验证。它不影响数据库或者您可以在表单之外手动设置空值。
As for blank=False, that only affects forms. It just makes the form set the field as required=True so it won't validate unless it has a value. It doesn't affect the database or your ability to manually set a blank value outside of a form.
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