Django模型中没有这样的列错误 [英] No such column error in Django models
本文介绍了Django模型中没有这样的列错误的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我在Django模型中添加了一个新字段，但是无论新字段是什么，当我尝试运行makemigrations时都不会出现此类错误
I'm adding a new field to my Django model, but no matter what the new field is, I get a no such column error when I try to run makemigrations
File "/Users/hugokitano/canopy/lib/python2.7/site-packages/django/db/backends/sqlite3/base.py", line 318, in execute
return Database.Cursor.execute(self, query, params)
django.db.utils.OperationalError: no such column: stats_control.con_LD_file
这是我的模型代码现在的样子。如果已注释的字段未注释，则它将失败上述的 makemigrations调用。
Here's what my code for the model looks like now. If the commented field is uncommented, it will fail the "makemigrations" call like above.
class Control(models.Model):
submissions = models.ManyToManyField(Submission, blank=True)
con_name = models.CharField('name', max_length=200)
con_bed_file = models.FileField('.bed file', upload_to='controls')
con_bim_file = models.FileField('.bim file', upload_to='controls')
con_fam_file = models.FileField('.fam file', upload_to='controls')
con_SNPs = models.IntegerField('# of SNPs', default = 0, blank=True, null=True)
#con_LD_file = models.FileField('LD score file', upload_to='LD_scores', blank=True, null=True)
def __unicode__(self): # __unicode__ on Python 2
return self.con_name
编辑：这还有其他一些事情
here are some other things
Traceback (most recent call last):
File "manage.py", line 10, in <module>
execute_from_command_line(sys.argv)
File "/Users/hugokitano/canopy/lib/python2.7/site-packages/django/core/management/__init__.py", line 338, in execute_from_command_line
utility.execute()
File "/Users/hugokitano/canopy/lib/python2.7/site-packages/django/core/management/__init__.py", line 312, in execute
django.setup()
File "/Users/hugokitano/canopy/lib/python2.7/site-packages/django/__init__.py", line 18, in setup
apps.populate(settings.INSTALLED_APPS)
File "/Users/hugokitano/canopy/lib/python2.7/site-packages/django/apps/registry.py", line 108, in populate
app_config.import_models(all_models)
File "/Users/hugokitano/canopy/lib/python2.7/site-packages/django/apps/config.py", line 198, in import_models
self.models_module = import_module(models_module_name)
File "/Applications/Canopy.app/appdata/canopy-1.5.4.3105.macosx-x86_64/Canopy.app/Contents/lib/python2.7/importlib/__init__.py", line 37, in import_module
__import__(name)
File "/Users/hugokitano/Documents/Summer_Code/statread/stats/models.py", line 39, in <module>
class CompareForm(forms.Form):
File "/Users/hugokitano/Documents/Summer_Code/statread/stats/models.py", line 40, in CompareForm
select = forms.MultipleChoiceField(widget=forms.CheckboxSelectMultiple,required=False,choices=( (x.id, x.con_name) for x in CONTROL_CHOICES) )
File "/Users/hugokitano/canopy/lib/python2.7/site-packages/django/db/models/query.py", line 162, in __iter__
self._fetch_all()
File "/Users/hugokitano/canopy/lib/python2.7/site-packages/django/db/models/query.py", line 965, in _fetch_all
self._result_cache = list(self.iterator())
File "/Users/hugokitano/canopy/lib/python2.7/site-packages/django/db/models/query.py", line 238, in iterator
results = compiler.execute_sql()
File "/Users/hugokitano/canopy/lib/python2.7/site-packages/django/db/models/sql/compiler.py", line 840, in execute_sql
cursor.execute(sql, params)
File "/Users/hugokitano/canopy/lib/python2.7/site-packages/django/db/backends/utils.py", line 79, in execute
return super(CursorDebugWrapper, self).execute(sql, params)
File "/Users/hugokitano/canopy/lib/python2.7/site-packages/django/db/backends/utils.py", line 64, in execute
return self.cursor.execute(sql, params)
File "/Users/hugokitano/canopy/lib/python2.7/site-packages/django/db/utils.py", line 97, in __exit__
six.reraise(dj_exc_type, dj_exc_value, traceback)
File "/Users/hugokitano/canopy/lib/python2.7/site-packages/django/db/backends/utils.py", line 64, in execute
return self.cursor.execute(sql, params)
File "/Users/hugokitano/canopy/lib/python2.7/site-packages/django/db/backends/sqlite3/base.py", line 318, in execute
return Database.Cursor.execute(self, query, params)
django.db.utils.OperationalError: no such column: stats_control.con_LD_file
设置：
Django settings for statread project.
Generated by 'django-admin startproject' using Django 1.8.3.
For more information on this file, see
https://docs.djangoproject.com/en/1.8/topics/settings/
For the full list of settings and their values, see
https://docs.djangoproject.com/en/1.8/ref/settings/
"""
# Build paths inside the project like this: os.path.join(BASE_DIR, ...)
import os
BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
# Quick-start development settings - unsuitable for production
# See https://docs.djangoproject.com/en/1.8/howto/deployment/checklist/
# SECURITY WARNING: keep the secret key used in production secret!
SECRET_KEY = 'igl9^f%j_3&2kk)iuo8lofz%3zzs$v!j+(-#tgl!^==il)k^yo'
# SECURITY WARNING: don't run with debug turned on in production!
DEBUG = True
ALLOWED_HOSTS = []
# Application definition
INSTALLED_APPS = (
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'stats',
)
MIDDLEWARE_CLASSES = (
'django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.common.CommonMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.auth.middleware.SessionAuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware',
'django.middleware.clickjacking.XFrameOptionsMiddleware',
'django.middleware.security.SecurityMiddleware',
)
ROOT_URLCONF = 'statread.urls'
TEMPLATES = [
{
'BACKEND': 'django.template.backends.django.DjangoTemplates',
'DIRS': [],
'APP_DIRS': True,
'OPTIONS': {
'context_processors': [
'django.template.context_processors.debug',
'django.template.context_processors.request',
'django.contrib.auth.context_processors.auth',
'django.contrib.messages.context_processors.messages',
],
},
},
]
WSGI_APPLICATION = 'statread.wsgi.application'
# Database
# https://docs.djangoproject.com/en/1.8/ref/settings/#databases
DATABASES = {
'default': {
'ENGINE': 'django.db.backends.sqlite3',
'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
}
}
# Internationalization
# https://docs.djangoproject.com/en/1.8/topics/i18n/
LANGUAGE_CODE = 'en-us'
TIME_ZONE = 'America/Los_Angeles'
USE_I18N = True
USE_L10N = True
USE_TZ = True
# Static files (CSS, JavaScript, Images)
# https://docs.djangoproject.com/en/1.8/howto/static-files/
STATIC_URL = '/static/'
MEDIA_ROOT = '/Users/hugokitano/Documents/Summer_Code/storage'
MEDIA_URL = 'http://127.0.0.1:8000/stats/media/'
模型：
from django.db import models
from django import forms
from django.forms import ModelForm
from django.utils import timezone
from picklefield.fields import PickledObjectField
#from django.contrib.auth.models import User
class Submission(models.Model):
sub_name = models.CharField(max_length=200)
sub_file = models.FileField(upload_to='statistics')
sub_date = models.DateTimeField('date submitted', blank=True, null=True, default=timezone.now)
def __unicode__(self): # __unicode__ on Python 2
return self.sub_name
class Output(models.Model):
submission = models.OneToOneField(Submission)
data = PickledObjectField()
outputFile = models.FileField('Output file', upload_to='outputs', blank = True, null = True)
numSNPs = models.IntegerField(default=0)
class Control(models.Model):
submissions = models.ManyToManyField(Submission, blank=True)
con_name = models.CharField('name', max_length=200)
con_bed_file = models.FileField('.bed file', upload_to='controls')
con_bim_file = models.FileField('.bim file', upload_to='controls')
con_fam_file = models.FileField('.fam file', upload_to='controls')
con_SNPs = models.IntegerField('# of SNPs', default = 0, blank=True, null=True)
con_LD_file = models.FileField('LD score file', upload_to='LD_scores', blank=True, null=True)
def __unicode__(self): # __unicode__ on Python 2
return self.con_name
class SubmissionForm(ModelForm):
class Meta:
model = Submission
fields = ['sub_name', 'sub_file']
CONTROL_CHOICES = Control.objects.all()
class CompareForm(forms.Form):
select = forms.MultipleChoiceField(widget=forms.CheckboxSelectMultiple,required=False,choices=( (x.id, x.con_name) for x in CONTROL_CHOICES) )
class ControlForm(ModelForm):
class Meta:
model = Control
fields = ['con_name', 'con_bed_file', 'con_bim_file', 'con_fam_file']
推荐答案
这里的问题是当模型仍在加载且应用未完全初始化时，您正在查询数据库：
The problem here is you're querying the database while models are still loading and apps are not fully initialized:
File "/Users/hugokitano/Documents/Summer_Code/statread/stats/models.py", line 40, in CompareForm
select = forms.MultipleChoiceField(widget=forms.CheckboxSelectMultiple,required=False,choices=( (x.id, x.con_name) for x in CONTROL_CHOICES) )
CONTROL_CHOICES 是先前在文件中定义的查询集：
CONTROL_CHOICES is a queryset defined earlier in your file:
CONTROL_CHOICES = Control.objects.all()
为简单起见，请永远不要这样做。如果在未完全加载应用程序的情况下查询数据库，则所有内容都会崩溃。
To keep it simple, never, never do this. If you query the database while your apps are not fully loaded, everything will crash.
此外，您的代码也将无法正常运行：
Also, your code will not behave as expected:
class CompareForm(forms.Form):
select = forms.MultipleChoiceField(widget=forms.CheckboxSelectMultiple,required=False,choices=( (x.id, x.con_name) for x in CONTROL_CHOICES) )
因为您直接在查询集中迭代您的表单定义中，您将获得一个静态元素列表，这些元素在您重新启动服务器之前不会改变（即使您在数据库中添加了新元素）。
Since you are iterating on the queryset directly in your form definition, you will get a static list of elements that will never change (even if you add new ones in database) until you restart your server.
此处的解决方案是摆脱 forms.MultipleChoiceField 和 CONTROL_CHOICES 并使用 ModelMultipleChoiceField 。
专门针对这种情况设计：
The solution Here is to get rid of forms.MultipleChoiceField and CONTROL_CHOICES and use ModelMultipleChoiceField.
It is designed specifically for this case:
class CompareForm(forms.Form):
select = forms.ModelMultipleChoiceField(queryset=Control.objects.all())
由于对查询集的计算是惰性的，显示表单时，您将直接从数据库获取最新的对象。
Django还将为您处理验证和所有操作。
As the queryset is lazily evaluated, you'll get up-to-dase objects straight from the database when displaying the form. Django will also handle validation and everything for you.
这篇关于Django模型中没有这样的列错误的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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