python - choice_set django 教程第一部分

Question

这个问题就在 Django (1.3)教程之外。

关于choice_set 命令和本教程还有其他帖子，但似乎都没有我遇到的问题。

在本教程的这一部分中，我们将投票应用程序添加到 mysite。尝试向“投票”问题添加选项时出现错误。它告诉我没有名为“选择”的列，但在 models.py 中有一个“选择”类，它被导入了。

以下代码是产生错误的地方：

p.choice_set.all()

DatabaseError: no such column: polls_choice.choice

但是分析器应该是：

[]

mysite/polls/models.py 代码：

from django.db import models
import datetime
# Create your models here.

class Poll(models.Model):
    question = models.CharField(max_length=200)
    pub_date = models.DateTimeField('date published')
    def __unicode__(self):
        return self.question
    def was_published_today(self):
        return self.pub_date.date() == datetime.date.today()

class Choice(models.Model):
    poll = models.ForeignKey(Poll)
    choice = models.CharField(max_length=200)
    votes = models.IntegerField()
    def __unicode__(self):
        return self.choice

如果您能提供任何建议，我将非常感谢您的努力。谢谢。

这是长表格，

03:30 ~ $ cd mysite                                                                                                                                                             
03:30 ~/mysite $ python manage.py sql polls
BEGIN;
CREATE TABLE "polls_poll" (
    "id" integer NOT NULL PRIMARY KEY,
    "question" varchar(200) NOT NULL,
    "pub_date" datetime NOT NULL
)                                                                                                                                                                               
;                                                                                                                                                                               
CREATE TABLE "polls_choice" (
    "id" integer NOT NULL PRIMARY KEY,
    "poll_id" integer NOT NULL REFERENCES "polls_poll" ("id"),
    "choice" varchar(200) NOT NULL,
    "votes" integer NOT NULL
)                                                                                                                                                                               
;                                                                                                                                                                               
COMMIT;
03:30 ~/mysite $ python manage.py syncdb
Creating tables ...
Installing custom SQL ...
Installing indexes ...
No fixtures found.
04:09 ~/mysite $ pyton manage.py sql polls                                                                                                                                      
bash: pyton: command not found
04:10 ~/mysite $ python manage.py syncdb                                                                                                                                        
Creating tables ...
Installing custom SQL ...
Installing indexes ...
No fixtures found.
04:11 ~/mysite $ python manage.py sql polls
BEGIN;
CREATE TABLE "polls_poll" (
    "id" integer NOT NULL PRIMARY KEY,
    "question" varchar(200) NOT NULL,
    "pub_date" datetime NOT NULL
)                                                                                                                                                                               
;                                                                                                                                                                               
CREATE TABLE "polls_choice" (
    "id" integer NOT NULL PRIMARY KEY,
    "poll_id" integer NOT NULL REFERENCES "polls_poll" ("id"),
    "choice" varchar(200) NOT NULL,
    "votes" integer NOT NULL
)                                                                                                                                                                               
;                                                                                                                                                                               
COMMIT;
04:23 ~/mysite $ python manage.py shell                                                                                                                                         
Python 2.7.5+ (default, Sep 19 2013, 13:48:49) 
Type "copyright", "credits" or "license" for more information.

IPython 1.0.0 -- An enhanced Interactive Python.
?         -> Introduction and overview of IPython's features.
%quickref -> Quick reference.
help      -> Python's own help system.
object?   -> Details about 'object', use 'object??' for extra details.

In [1]: p= Poll.objects.all()
---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
/usr/local/lib/python2.7/dist-packages/django/core/management/commands/shell.py in <module>()
----> 1 p= Poll.objects.all()

NameError: name 'Poll' is not defined

In [2]: from polls.models import Poll, Choice                                                                                                                                   

In [3]: p=Poll.objects.all()                                                                                                                                                    

In [4]: print p
[<Poll: What's up?>, <Poll: What's up?>]                                                                                                                                        

In [5]: p=Poll.objects.get(pk=1)                                                                                                                                                
prin                                                                                                                                                                            
In [6]: print p
What's up?                                                                                                                                                                      

In [7]: p.choice_set.all()                                                                                                                                                      
Out[7]: ---------------------------------------------------------------------------
DatabaseError                             Traceback (most recent call last)
/usr/local/lib/python2.7/dist-packages/django/core/management/commands/shell.py in <module>()
----> 1 p.choice_set.all()

/usr/local/lib/python2.7/dist-packages/IPython/core/displayhook.py in __call__(self, result)
    245             self.start_displayhook()
    246             self.write_output_prompt()
--> 247             format_dict, md_dict = self.compute_format_data(result)
    248             self.write_format_data(format_dict, md_dict)
    249             self.update_user_ns(result)

/usr/local/lib/python2.7/dist-packages/IPython/core/displayhook.py in compute_format_data(self, result)
    155
    156         """
--> 157         return self.shell.display_formatter.format(result)
    158
    159     def write_format_data(self, format_dict, md_dict=None):

/usr/local/lib/python2.7/dist-packages/IPython/core/formatters.py in format(self, obj, include, exclude)
    150             md = None
    151             try:
--> 152                 data = formatter(obj)
    153             except:
    154                 # FIXME: log the exception

/usr/local/lib/python2.7/dist-packages/IPython/core/formatters.py in __call__(self, obj)
    479                 type_pprinters=self.type_printers,
    480                 deferred_pprinters=self.deferred_printers)
--> 481             printer.pretty(obj)
    482             printer.flush()
    483             return stream.getvalue()

/usr/local/lib/python2.7/dist-packages/IPython/lib/pretty.py in pretty(self, obj)
    360                             if callable(meth):
    361                                 return meth(obj, self, cycle)
--> 362             return _default_pprint(obj, self, cycle)
    363         finally:
    364             self.end_group()

/usr/local/lib/python2.7/dist-packages/IPython/lib/pretty.py in _default_pprint(obj, p, cycle)
    480     if getattr(klass, '__repr__', None) not in _baseclass_reprs:
    481         # A user-provided repr.
--> 482         p.text(repr(obj))
    483         return
    484     p.begin_group(1, '<')

/usr/local/lib/python2.7/dist-packages/django/db/models/query.py in __repr__(self)
     67
     68     def __repr__(self):
---> 69         data = list(self[:REPR_OUTPUT_SIZE + 1])
     70         if len(data) > REPR_OUTPUT_SIZE:
     71             data[-1] = "...(remaining elements truncated)..."

/usr/local/lib/python2.7/dist-packages/django/db/models/query.py in __len__(self)
     82                 self._result_cache = list(self.iterator())
     83         elif self._iter:
---> 84             self._result_cache.extend(self._iter)
     85         return len(self._result_cache)
     86

/usr/local/lib/python2.7/dist-packages/django/db/models/query.py in iterator(self)
    271         model = self.model
    272         compiler = self.query.get_compiler(using=db)
--> 273         for row in compiler.results_iter():
    274             if fill_cache:
    275                 obj, _ = get_cached_row(model, row,

/usr/local/lib/python2.7/dist-packages/django/db/models/sql/compiler.py in results_iter(self)
    678         fields = None
    679         has_aggregate_select = bool(self.query.aggregate_select)
--> 680         for rows in self.execute_sql(MULTI):
    681             for row in rows:
    682                 if resolve_columns:

/usr/local/lib/python2.7/dist-packages/django/db/models/sql/compiler.py in execute_sql(self, result_type)
    733
    734         cursor = self.connection.cursor()
--> 735         cursor.execute(sql, params)
    736
    737         if not result_type:

/usr/local/lib/python2.7/dist-packages/django/db/backends/util.py in execute(self, sql, params)
     32         start = time()
     33         try:
---> 34             return self.cursor.execute(sql, params)
     35         finally:
     36             stop = time()

/usr/local/lib/python2.7/dist-packages/django/db/backends/sqlite3/base.py in execute(self, query, params)
    232         query = self.convert_query(query)
    233         try:
--> 234             return Database.Cursor.execute(self, query, params)
    235         except Database.IntegrityError, e:
    236             raise utils.IntegrityError, utils.IntegrityError(*tuple(e)), sys.exc_info()[2]

DatabaseError: no such column: polls_choice.choice

In [8]:

score 2 · Accepted Answer

我让它工作。我在 settings.py 中向我的数据库添加了另一个级别：

DATABASES = {
    'default': {
    'ENGINE': 'django.db.backends.sqlite3',
    'NAME': '/home/JoeButy/mysite/polls/db.sqlite',
    'USER': '',
    'PASSWORD': '',
    'HOST': '',
    'PORT': ''
    }
}

这是我的安装位：

INSTALLED_APPS = (
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.sites',
    'mysite.polls',
    'mysite.myapp',
)

谢谢您的帮助。我希望其他人可以从中学习！干杯！

这是整个附录代码：

06:15 ~ $ cd mysite                                                   
06:16 ~/mysite $ python ./manage.py syncdb                            
Creating tables ...
Creating table auth_permission
Creating table auth_group_permissions
Creating table auth_group
Creating table auth_user_user_permissions
Creating table auth_user_groups
Creating table auth_user
Creating table auth_message
Creating table django_content_type
Creating table django_session
Creating table django_site
Creating table polls_poll
Creating table polls_choice

You just installed Django's auth system, which means you don't have an
y superusers defined.
Would you like to create one now? (yes/no): yes
Username (Leave blank to use 'joebuty'): 
E-mail address: joebuty@gmail.com
Password: 
Password (again): 
Superuser created successfully.
Installing custom SQL ...
Installing indexes ...
No fixtures found.
06:17 ~/mysite $ python ./manage.py sql polls
BEGIN;
CREATE TABLE "polls_poll" (
    "id" integer NOT NULL PRIMARY KEY,
    "question" varchar(200) NOT NULL,
    "pub_date" datetime NOT NULL
)                                                                     
;                                                                     
CREATE TABLE "polls_choice" (
    "id" integer NOT NULL PRIMARY KEY,
    "poll_id" integer NOT NULL REFERENCES "polls_poll" ("id"),
    "choice" varchar(200) NOT NULL,
    "votes" integer NOT NULL
)                                                                     
;                                                                     
COMMIT;
06:17 ~/mysite $ python ./manage.py shell                             
Python 2.7.5+ (default, Sep 19 2013, 13:48:49) 
Type "copyright", "credits" or "license" for more information.

IPython 1.0.0 -- An enhanced Interactive Python.
?         -> Introduction and overview of IPython's features.
%quickref -> Quick reference.
help      -> Python's own help system.
object?   -> Details about 'object', use 'object??' for extra details.

In [1]: from polls.models import Poll, Choice

In [2]: p=Poll.objects.get(pk=1)
----------------------------------------------------------------------
-----                                                                 
DoesNotExist                              Traceback (most recent call 
last)                                                                 
/usr/local/lib/python2.7/dist-packages/django/core/management/commands
/shell.py in <module>()                                               
----> 1 p=Poll.objects.get(pk=1)

/usr/local/lib/python2.7/dist-packages/django/db/models/manager.py in 
get(self, *args, **kwargs)
    130
    131     def get(self, *args, **kwargs):
--> 132         return self.get_query_set().get(*args, **kwargs)
    133
    134     def get_or_create(self, **kwargs):

/usr/local/lib/python2.7/dist-packages/django/db/models/query.py in ge
t(self, *args, **kwargs)
    347         if not num:
    348             raise self.model.DoesNotExist("%s matching query d
oes not exist."                                                       
--> 349                     % self.model._meta.object_name)
    350         raise self.model.MultipleObjectsReturned("get() return
ed more than one %s -- it returned %s! Lookup parameters were %s"     
    351                 % (self.model._meta.object_name, num, kwargs))

DoesNotExist: Poll matching query does not exist.

In [3]: p=Poll.objects.all()                                          

In [4]: print p
[]                                                                    

In [5]: p =Poll(question="What''s up?", pub_date=datetime.datetime.now
())
----------------------------------------------------------------------
-----                                                                 
NameError                                 Traceback (most recent call 
last)                                                                 
/usr/local/lib/python2.7/dist-packages/django/core/management/commands
/shell.py in <module>()                                               
----> 1 p =Poll(question="What''s up?", pub_date=datetime.datetime.now
())                                                                   

NameError: name 'datetime' is not defined

In [6]: import datetime

In [7]: p =Poll(question="What''s up?", pub_date=datetime.datetime.now
())                                                                   

In [8]: print p
What''s up?                                                           

In [9]: p.save()

In [10]: p=Poll.objects.get(pk=1)

In [11]: p.was_published_today()
Out[11]: True

In [12]: p.choice_set.all()
Out[12]: []

In [13]: p.choice_set.create(choice="Not much", votes=0)
Out[13]: <Choice: Not much>

In [14]: p.choice_set.create(choice="The Sky", votes=0)               
Out[14]: <Choice: The Sky>

In [15]: p.choice_set.create(choice="Best Web App Ever!", votes=0)    
Out[15]: <Choice: Best Web App Ever!>

In [16]: c.poll
----------------------------------------------------------------------
-----                                                                 
NameError                                 Traceback (most recent call 
last)                                                                 
/usr/local/lib/python2.7/dist-packages/django/core/management/commands
/shell.py in <module>()                                               
----> 1 c.poll

NameError: name 'c' is not defined

In [17]: p.choice_set.all()
Out[17]: [<Choice: Not much>, <Choice: The Sky>, <Choice: Best Web App
 Ever!>]                                                              

In [18]: p.choice_set.count()                                         
Out[18]: 3

In [19]: Choice.objects.filter(poll__pub_date__year=2014)             
Out[19]: [<Choice: Not much>, <Choice: The Sky>, <Choice: Best Web App
 Ever!>]                                                              

In [20]: c.save()
----------------------------------------------------------------------
-----                                                                 
NameError                                 Traceback (most recent call 
last)                                                                 
/usr/local/lib/python2.7/dist-packages/django/core/management/commands
/shell.py in <module>()                                               
----> 1 c.save()

NameError: name 'c' is not defined

In [21]:

python - choice_set django 教程第一部分

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