Django 表单仅在第二次请求后有效

Question

我对 django 表单有一个非常奇怪的问题，我显示一个包含附加表单集的表单，以便用户还可以同时提交外键关系的数据。

模板始终显示原始模型的一个表单和第二个模型的一个表单。

我现在想提交两份表格，而不在第二份表格中填写任何内容。 第一次提交时，第二个表单未验证并重新显示页面，但第二次提交时，第二个表单有效！即使如此，POST 数据也是相同的。 这怎么可能？

或者也许我这样做完全错误，你如何辨别用户是否没有填写表单集中的任何内容或者他是否填写了无效的内容？

这里是模型：

class Software(models.Model):
    creation_date = models.DateTimeField(default=datetime.now)
    creator = models.ForeignKey(User)
    version = models.CharField(max_length=300, unique=True, editable=False)
    major_version = models.IntegerField()
    minor_version = models.IntegerField()
    [...]

    def save(self, **kwargs):
        """
        This updates the version string to the combined representation.
        """
        self.version = Software.combine_version_string (self.major_version, self.minor_version)
        super(Software, self).save(**kwargs)

class SoftwarePatch(models.Model):
    file  = models.FileField(upload_to='software_patches')
    file_name = models.CharField(max_length=255, editable=False)
    file_date = models.DateTimeField(default=datetime.now)
    upload_date = models.DateTimeField(default=datetime.now)
    software = models.ForeignKey('Software', related_name='patches')
    firmware_patch = models.BooleanField(default=True)
    target_path = models.CharField(max_length=255, blank=True)

    class Meta:
        unique_together = ('software', 'file_name')
        verbose_name_plural = "software patches"

    def __unicode__(self):        
        return self.file_name

    def clean(self):
          if self.file and not self.file_name:
              self.file_name = self.file.file.name 

这里是我的表单：

SoftwarePatchFormSet = inlineformset_factory(Software, 
    SoftwarePatch, 
    extra=1)


class SoftwareForm(forms.ModelForm):
    """
    A simple form for creating a new software.
    """
    class Meta:
        model = Software

最后是我的视图函数：

def software_add(request, software_id=None):
    if software_id == None:
        software = Software()
    else:
        software = Software.objects.get(id=software_id)

    if request.POST:        
        form = SoftwareForm(request.POST, instance=software)        

        if form.is_valid():
            software = form.save(commit=False)
            softwarepatch_formset = SoftwarePatchFormSet(request.POST, request.FILES, instance=software)

            if softwarepatch_formset.is_valid():
                software = form.save()
                softwarepatch_formset.save()

                # Redirect, in case of a popup close it
                if request.POST.has_key("_popup"):
                    pk_value = software._get_pk_val()
                    return HttpResponse('<script type="text/javascript">opener.dismissAddAnotherPopup(window, "%s", "%s");</script>' % \
                        # escape() calls force_unicode.
                        (escape(pk_value), escape(software)))
                if 'next' in request.POST:
                    return HttpResponseRedirect(request.POST['next'])
                else:
                    return HttpResponseRedirect(reverse('index'))
    else:
        form = SoftwareForm(instance=software)
        softwarepatch_formset = SoftwarePatchFormSet(instance=software)

    is_popup = request.GET.has_key("_popup") or request.POST.has_key("_popup")

    return render_to_response(
        'main/software_edit.html',
        {'form': form,
         'softwarepatch_formset': softwarepatch_formset,
         'add': True,
         'is_popup': is_popup,
        },
        context_instance = RequestContext(request)
    )

Answer 1

首先，您应该仅在为现有对象（即数据库中已有的对象）创建表单/表单集时设置实例参数。例如，如果 software_id = None 并且它是 GET 请求，则您应该只执行 form = SoftwareForm()。

另外，在执行 software = form.save(commit=False) 后，您应该执行 software.save() 而不是 software = form.save()< /代码>。 [不过，我认为这并不是真正的问题，只是您正在重做保存]。请记住，如果 Software 模型中有 ManyToManyField，则需要在 software = form.save() 之后执行 form.save_m2m()以及。

这是我认为你应该拥有的：

def software_add(request, software_id=None):
    if request.POST: 
        if software_id:
            software = Software.objects.get(id=software_id)
            form = SoftwareForm(request.POST, instance=software)
        else:
            form = SoftwareForm(request.POST)

        if form.is_valid():
            software = form.save(commit=False)
            softwarepatch_formset = SoftwarePatchFormSet(request.POST, request.FILES, instance=software)

            if softwarepatch_formset.is_valid():
                software.save()
                softwarepatch_formset.save()

                # Redirect, in case of a popup close it
                if request.POST.has_key("_popup"):
                    pk_value = software._get_pk_val()
                    return HttpResponse('<script type="text/javascript">opener.dismissAddAnotherPopup(window, "%s", "%s");</script>' % \
                        # escape() calls force_unicode.
                        (escape(pk_value), escape(software)))
                if 'next' in request.POST:
                    return HttpResponseRedirect(request.POST['next'])
                else:
                    return HttpResponseRedirect(reverse('index'))
        else:
            softwarepatch_formset = SoftwarePatchFormSet(request.POST, request.FILES)     
    else:
        if software_id:
            software = Software.objects.get(id=software_id)
            form = SoftwareForm(instance=software)
            softwarepatch_formset = SoftwarePatchFormSet(instance=software)
        else:
            form = SoftwareForm()
            softwarepatch_formset = SoftwarePatchFormSet()


    is_popup = request.GET.has_key("_popup") or request.POST.has_key("_popup")

    return render_to_response(
        'main/software_edit.html',
        {'form': form,
         'softwarepatch_formset': softwarepatch_formset,
         'add': True,
         'is_popup': is_popup,
        },
        context_instance = RequestContext(request)
    )

Answer 2

好吧，我终于找到了我的问题！

我有以下模型字段： file_date = models.DateTimeField(default=datetime.now)

这将 innital-file-date 设置为如下值： u'2011-10-18 08:14:30.242000'
通过 html 小部件渲染后，该值将是： u'2011-10-18 08:14:30'
所以django会认为表单已更改，因此不会保存。

在第二次加载时，django 会自动将截断的值设置为初始文件日期，然后不会更改任何内容，并且保存按预期进行。

所以现在我只需要弄清楚使用什么而不是 datetime.now 。当我弄清楚后，我会更新这篇文章。