python - ModelChoiceField 导致 decimal.invalidoperation，即使模型上的 def __str__ 设置为返回名称

Question

我有一个 forms.py 和这个小块：

 from mainpage.models import Institution

  institution = forms.ModelChoiceField(queryset=Institution.objects.all(), empty_label="(Select One)", 
        to_field_name="institution_name", 
        widget=forms.Select(
            attrs={
                'tabindex':'7','class':'form-control'
            }
        )
    )   

一旦我有这段代码，它就会导致decimal.invalidoperation，即使我的机构模型就是这样（在另一个应用程序中）

class Institution(models.Model):
    objects = models.Manager()

    institution_id = models.CharField(max_length=10)
    institution_name = models.CharField(max_length=100)
    institution_precentages = models.DecimalField(max_digits = 4, decimal_places=2) #might have to change this



    def __str__(self):
        return self.institution_name

我什至在视图中进行了测试，试图快速渲染所有这些

   p = Institution.objects.first()
   print(p)

工作正常，不知道还有什么可以尝试或我错过了什么。

编辑：完整的堆栈跟踪：

Starting development server at http://127.0.0.1:8000/
Quit the server with CONTROL-C.
[03/Oct/2019 15:31:22] "GET / HTTP/1.1" 200 44551
[03/Oct/2019 15:31:22] "GET /static/img/apo-img/moon.jpg HTTP/1.1" 304 0
[03/Oct/2019 15:31:22] "GET /static/img/apo-img/b4.jpg HTTP/1.1" 200 492566
[03/Oct/2019 15:31:22] "GET /static/img/site-img/saturn.png HTTP/1.1" 200 223493
[03/Oct/2019 15:31:22] "GET /static/js/uza.bundle.js HTTP/1.1" 200 161266
[03/Oct/2019 15:31:22] "GET /static/img/apo-img/b3.jpg HTTP/1.1" 200 2012230
[03/Oct/2019 15:31:22] "GET /static/img/site-img/sloanmilkyway.png HTTP/1.1" 200 2609664
Internal Server Error: /accounts/signup/
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/site-packages/django/core/handlers/exception.py", line 34, in inner
    response = get_response(request)
  File "/usr/local/lib/python3.7/site-packages/django/core/handlers/base.py", line 115, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "/usr/local/lib/python3.7/site-packages/django/core/handlers/base.py", line 113, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/Users/shathoma/programming/web/django_apo/accounts/views.py", line 75, in signup
    return render(request, 'signup.html', {'form': form, 'profile_form': profile_form})
  File "/usr/local/lib/python3.7/site-packages/django/shortcuts.py", line 36, in render
    content = loader.render_to_string(template_name, context, request, using=using)
  File "/usr/local/lib/python3.7/site-packages/django/template/loader.py", line 62, in render_to_string
    return template.render(context, request)
  File "/usr/local/lib/python3.7/site-packages/django/template/backends/django.py", line 61, in render
    return self.template.render(context)
  File "/usr/local/lib/python3.7/site-packages/django/template/base.py", line 171, in render
    return self._render(context)
  File "/usr/local/lib/python3.7/site-packages/django/template/base.py", line 163, in _render
    return self.nodelist.render(context)
  File "/usr/local/lib/python3.7/site-packages/django/template/base.py", line 937, in render
    bit = node.render_annotated(context)
  File "/usr/local/lib/python3.7/site-packages/django/template/base.py", line 904, in render_annotated
    return self.render(context)
  File "/usr/local/lib/python3.7/site-packages/django/template/loader_tags.py", line 150, in render
    return compiled_parent._render(context)
  File "/usr/local/lib/python3.7/site-packages/django/template/base.py", line 163, in _render
    return self.nodelist.render(context)
  File "/usr/local/lib/python3.7/site-packages/django/template/base.py", line 937, in render
    bit = node.render_annotated(context)
  File "/usr/local/lib/python3.7/site-packages/django/template/base.py", line 904, in render_annotated
    return self.render(context)
  File "/usr/local/lib/python3.7/site-packages/django/template/loader_tags.py", line 62, in render
    result = block.nodelist.render(context)
  File "/usr/local/lib/python3.7/site-packages/django/template/base.py", line 937, in render
    bit = node.render_annotated(context)
  File "/usr/local/lib/python3.7/site-packages/django/template/base.py", line 904, in render_annotated
    return self.render(context)
  File "/usr/local/lib/python3.7/site-packages/django/template/base.py", line 993, in render
    return render_value_in_context(output, context)
  File "/usr/local/lib/python3.7/site-packages/django/template/base.py", line 972, in render_value_in_context
    value = str(value)
  File "/usr/local/lib/python3.7/site-packages/django/utils/html.py", line 388, in <lambda>
    klass.__str__ = lambda self: mark_safe(klass_str(self))
  File "/usr/local/lib/python3.7/site-packages/django/forms/boundfield.py", line 33, in __str__
    return self.as_widget()
  File "/usr/local/lib/python3.7/site-packages/django/forms/boundfield.py", line 93, in as_widget
    renderer=self.form.renderer,
  File "/usr/local/lib/python3.7/site-packages/django/forms/widgets.py", line 241, in render
    context = self.get_context(name, value, attrs)
  File "/usr/local/lib/python3.7/site-packages/django/forms/widgets.py", line 680, in get_context
    context = super().get_context(name, value, attrs)
  File "/usr/local/lib/python3.7/site-packages/django/forms/widgets.py", line 641, in get_context
    context['widget']['optgroups'] = self.optgroups(name, context['widget']['value'], attrs)
  File "/usr/local/lib/python3.7/site-packages/django/forms/widgets.py", line 589, in optgroups
    for index, (option_value, option_label) in enumerate(self.choices):
  File "/usr/local/lib/python3.7/site-packages/django/forms/models.py", line 1137, in __iter__
    for obj in queryset:
  File "/usr/local/lib/python3.7/site-packages/django/db/models/query.py", line 341, in _iterator
    yield from self._iterable_class(self, chunked_fetch=use_chunked_fetch, chunk_size=chunk_size)
  File "/usr/local/lib/python3.7/site-packages/django/db/models/query.py", line 72, in __iter__
    for row in compiler.results_iter(results):
  File "/usr/local/lib/python3.7/site-packages/django/db/models/sql/compiler.py", line 1044, in apply_converters
    value = converter(value, expression, connection)
  File "/usr/local/lib/python3.7/site-packages/django/db/backends/sqlite3/operations.py", line 285, in converter
    return create_decimal(value).quantize(quantize_value, context=expression.output_field.context)
decimal.InvalidOperation: [<class 'decimal.InvalidOperation'>]
[03/Oct/2019 15:31:25] "GET /accounts/signup/ HTTP/1.1" 500 219301
Exception ignored in: <generator object cursor_iter at 0x10e417228>
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/site-packages/django/db/models/sql/compiler.py", line 1515, in cursor_iter
    cursor.close()
sqlite3.ProgrammingError: Cannot operate on a closed database.

标签： pythondjangosqlite

Answer 1

当我在一个写得不好的测试中打破外键约束时，我得到了这个错误（在关闭的数据库上操作）