Paper.objects.filter(Journal__Name='Science').order_by("-PublishedDate")
Read the documentation please.
On Fri, Dec 26, 2008 at 8:43 PM, 夏恺 <xia...@gmail.com> wrote:
>
> Hi all!
>
> I'm working on an app which has two classes:
>
> # This one records acedemic journal name and related infomation:
> class Journals(models.Model):
> Name = models.CharField(u'Journal', max_length=200, unique=True)
> IsSelected = models.BooleanField(u'If it is a special journal',
> default = False)
> IsTopped = models.BooleanField(u'Should it be placed at the top of
> the journal selection box?',
> default = False)
>
> class Meta:
> ordering = ('-IsSelected', '-IsTopped', 'Name', )
>
> def __unicode__(self):
> return u"%s" % (self.Name)
>
>
> # This one records paper infomation:
> class Paper(models.Model):
> # Many other fields are ommitted.
> Journal = models.ForeignKey(Journals, verbose_name="Journal Name")
>
>
>
> And in a view, I wrote a query:
>
> paper_list =
> Paper.objects.filter(Journal='Science').order_by("-PublishedDate")
>
>
>
> However, this one failed, complaining some DataError, invalid interger
> type input grammar.
>
> From the debug infomation, I learnt that Django tried to do a sql query
> like:
>
> 'SELECT COUNT(*) FROM "paper_paper" WHERE "paper_paper"."Journal_id" =
> E\'Science\' '
>
> which would certainly fail, since 'Science' is a string, and that
> Journal_id(an automatically defined field by Django) is of type integer.
>
>
> The problem is, why Django mis-translated that query? And how could I
> fix this problem?
>
> Many thanks!
>
>
> Detailed Debug info:
> Environment:
>
> Request Method: GET
> Request URL: http://cmr.nju.edu.cn/Paper/Science/
> Django Version: 1.1 pre-alpha SVN-9665
> Python Version: 2.4.3
> Installed Applications:
> ['django.contrib.auth',
> 'django.contrib.contenttypes',
> 'django.contrib.sessions',
> 'django.contrib.sites',
> 'django.contrib.comments',
> 'django.contrib.admin',
> 'django.contrib.tagging',
> 'pld.globaltags',
> 'pld.home',
> 'pld.Profile',
> 'pld.news',
> 'pld.paper']
> Installed Middleware:
> ('django.middleware.common.CommonMiddleware',
> 'django.contrib.sessions.middleware.SessionMiddleware',
> 'django.middleware.locale.LocaleMiddleware',
> 'django.contrib.auth.middleware.AuthenticationMiddleware')
>
>
> Traceback:
> File "/usr/lib64/python2.4/site-packages/django/core/handlers/base.py"
> in get_response
> 86. response = callback(request, *callback_args,
> **callback_kwargs)
> File "/www/pld/paper/views.py" in byJournal
> 50. paper_page = paginator.page(page)
> File "/usr/lib64/python2.4/site-packages/django/core/paginator.py" in page
> 37. number = self.validate_number(number)
> File "/usr/lib64/python2.4/site-packages/django/core/paginator.py" in
> validate_number
> 28. if number > self.num_pages:
> File "/usr/lib64/python2.4/site-packages/django/core/paginator.py" in
> _get_num_pages
> 60. if self.count == 0 and not self.allow_empty_first_page:
> File "/usr/lib64/python2.4/site-packages/django/core/paginator.py" in
> _get_count
> 48. self._count = self.object_list.count()
> File "/usr/lib64/python2.4/site-packages/django/db/models/query.py" in
> count
> 296. return self.query.get_count()
> File "/usr/lib64/python2.4/site-packages/django/db/models/sql/query.py"
> in get_count
> 234. data = obj.execute_sql(SINGLE)
> File "/usr/lib64/python2.4/site-packages/django/db/models/sql/query.py"
> in execute_sql
> 1756. cursor.execute(sql, params)
> File "/usr/lib64/python2.4/site-packages/django/db/backends/util.py" in
> execute
> 19. return self.cursor.execute(sql, params)
>
> Exception Type: DataError at /Paper/Science/
> Exception Value: Error: Invalid Input Syntax for Integer: "Science"
>
>
>
> >
>
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