django修改models重建数据库的操作
第二次修改models.py以后再次
python manage.py makemigrations
提示如下
You are trying to add a non-nullable field 'address' to xc_users without a default; we can't do that (the database needs something to populate existing rows). Please select a fix: 1) Provide a one-off default now (will be set on all existing rows) 2) Qu
于是删除数据库表，继续报相同的错误
makemigration需要指定名称，然后migrate才能识别两次<span style="font-family: Arial, Helvetica, sans-serif;">makemigrations的不同</span>
python manage.py makemigrations --name sqlname
然后再执行：
python manage.py migrate
成功解决问题！
补充知识：django rest framework如何一次性序列化同一个数据库下多个model表数据在一个json页面下
在django项目中，首先我们要安装django-rest-mutiple-models
pip install django-rest-multiple-models
然后在setting配置中配置一下APP
INSTALLED_APPS = (
....
'drf_multiple_model',
)
在我们的views视图函数下引入
from drf_multiple_model.views import ObjectMultipleModelAPIView
如下两个模型
class Play(models.Model):
genre = models.CharField(max_length=100)
title = models.CharField(max_length=200)
pages = models.IntegerField()
class Poem(models.Model):
title = models.CharField(max_length=200)
style = models.CharField(max_length=100)
lines = models.IntegerField()
stanzas = models.IntegerField()
序列化如下
class PlaySerializer(serializers.ModelSerializer):
class Meta:
model = Play
fields = ('genre','title','pages')
class PoemSerializer(serializers.ModelSerializer):
class Meta:
model = Poem
fields = ('title','stanzas')
views中我们可以这么写，继承一个ObjectMutipleModelAPIView
from drf_multiple_model.views import ObjectMultipleModelAPIView
class TextAPIView(ObjectMultipleModelAPIView):
querylist = [
{'queryset': Play.objects.all(), 'serializer_class': PlaySerializer},
{'queryset': Poem.objects.filter(style='Sonnet'), 'serializer_class': PoemSerializer},
....
]
如果我们使用的url是router，那这里我们就应该继承ObjectMutipleModelAPIViewset
具体的引入
from drf_multiple_model.viewsets import ObjectMultipleModelAPIViewSet
DRF页面的显示效果如下
{
"Play" : [
{"genre": "Comedy", "title": "A Midsummer Night"s Dream", "pages": 350},
{"genre": "Tragedy", "title": "Romeo and Juliet", "pages": 300},
....
],
"Poem" : [
{"title": "Shall I compare thee to a summer"s day", "stanzas": 1},
{"title": "As a decrepit father takes delight", "stanzas": 1},
....
],
}
效果就是能在一个json页面下序列化出多个不同的model数据
我们还可以对每个表的数据进行分页
from drf_multiple_model.pagination import MultipleModelLimitOffsetPagination
views下可以这么写
class LimitPagination(MultipleModelLimitOffsetPagination):
default_limit = 10
意思是每个model默认显示前十条数据
如果前端需要，url上可以加上limit=5，自定义默认显示前五条数据
更多详细内容，github搜索DjangoRestMultipleModels
以上这篇django修改models重建数据库的操作就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持软件开发网。
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