通过模型向M2M添加数据
通过模型向M2M添加数据
提问于 2019-06-17 13:18:12
我试图为我的数据库记录一个基于网络的课程规划应用程序。我担心的是无法在中间表中记录views.py中的关系views.py，但是它在浏览器中的shell中工作，我有一个ValueError :精确查找的QuerySet值必须限制在一个使用切片的结果上。
反向切换到复制和粘贴视图
C:\Program Files\Python37\lib\site-packages\django\core\handlers\exception.py in inner
response = get_response(request)
...
▶ Local vars
C:\Program Files\Python37\lib\site-packages\django\core\handlers\base.py in _get_response
response = self.process_exception_by_middleware(e, request)
...
▶ Local vars
C:\Program Files\Python37\lib\site-packages\django\core\handlers\base.py in _get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
...
▶ Local vars
E:\PLACORESA\configuration\views.py in departemnent
cursus = get_object_or_404(Cursus, libelle_cursus=cursus )
...
▶ Local vars
C:\Program Files\Python37\lib\site-packages\django\shortcuts.py in get_object_or_404
return queryset.get(*args, **kwargs)
...
▶ Local vars
C:\Program Files\Python37\lib\site-packages\django\db\models\query.py in get
num = len(clone)
...
▶ Local vars
C:\Program Files\Python37\lib\site-packages\django\db\models\query.py in __len__
self._fetch_all()
...
▶ Local vars
C:\Program Files\Python37\lib\site-packages\django\db\models\query.py in _fetch_all
self._result_cache = list(self._iterable_class(self))
...
▶ Local vars
C:\Program Files\Python37\lib\site-packages\django\db\models\query.py in __iter__
results = compiler.execute_sql(chunked_fetch=self.chunked_fetch, chunk_size=self.chunk_size)
...
▶ Local vars
C:\Program Files\Python37\lib\site-packages\django\db\models\sql\compiler.py in execute_sql
sql, params = self.as_sql()
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▶ Local vars
C:\Program Files\Python37\lib\site-packages\django\db\models\sql\compiler.py in as_sql
where, w_params = self.compile(self.where) if self.where is not None else ("", [])
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▶ Local vars
C:\Program Files\Python37\lib\site-packages\django\db\models\sql\compiler.py in compile
sql, params = node.as_sql(self, self.connection)
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▶ Local vars
C:\Program Files\Python37\lib\site-packages\django\db\models\sql\where.py in as_sql
sql, params = compiler.compile(child)
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▶ Local vars
C:\Program Files\Python37\lib\site-packages\django\db\models\sql\compiler.py in compile
sql, params = node.as_sql(self, self.connection)
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▶ Local vars
C:\Program Files\Python37\lib\site-packages\django\db\models\lookups.py in as_sql
rhs_sql, rhs_params = self.process_rhs(compiler, connection)
...
▶ Local vars
C:\Program Files\Python37\lib\site-packages\django\db\models\lookups.py in process_rhs
'The QuerySet value for an exact lookup must be limited to '
...
▶ Local vars models.py
class Departement(models.Model):
code_departement=models.CharField("code du département", max_length=100, unique=True)
libelle_departement=models.CharField("Libellé du département", max_length=100)
faculte=models.ForeignKey("Faculte", on_delete=models.CASCADE)
cursus=models.ManyToManyField("Cursus", through="AvoirCursus")
class Cursus(models.Model):
code_cursus=models.CharField("Code du cursus", max_length=10, unique=True)
libelle_cursus=models.CharField("Libellé du cursus", max_length=100)
class AvoirCursus(models.Model):
cursus=models.ForeignKey("Cursus", on_delete=models.CASCADE)
departement=models.ForeignKey("Departement", on_delete=models.CASCADE)views.py
if request.method == 'POST':
f = forms.Departement_Form(request.POST)
if f.is_valid():
dept = f.save(commit=False)
code_departement = f.cleaned_data['code_departement'].upper()
dept.code_departement = code_departement
cursus = f.cleaned_data['cursus']
dept.save()
cursus = get_object_or_404(Cursus, libelle_cursus=cursus )
AvoirCursus(departement=dept, cursus=cursus)
return redirect('configuration:lister_departement')回答 2
Stack Overflow用户
发布于 2019-06-17 13:51:13
你确定那个cursus对象工作正常吗？也许表单中的cursus返回多个值或字符串？
同时，尝试在get_or_404之后添加打印(Cursus)，并查看里面的内容。
你到底想在这里做什么？
AvoirCursus(departement=dept，cursus=cursus)
你确定这不应该是
AvoirCursus.objects.create(departement=dept，cursus=cursus)
在没有堆栈跟踪的情况下很难找到答案。
Stack Overflow用户
发布于 2019-06-20 17:05:51
我成功地解决了我的遗嘱。视图中使用的表单是来自models.py的泛型表单。当我打印(Cursus)结果是在中间数据库中包含选定的items.To写的查询集时，我将"cursus“的过程设置为具有不同的对象。
**the views.py is:**
if f.is_valid():
dept = f.save(commit=False)
code_departement = f.cleaned_data['code_departement']
dept.code_departement = code_departement
print(code_departement)
cursus = f.cleaned_data['cursus']
dept.save()
for i in cursus:
AvoirCursus.objects.create(departement=dept, cursus=i)页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/56632185
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