Question

我正在尝试以仅包含与先前选择的选项相关的字段的形式创建一个选择字段。到目前为止，用户可以在站点上选择一个父选项（“我称为学科”），然后提交，要求他们在什么时候从一组字段中进行选择，这些字段是所选学科的子集。目前，除了第二页上的页面，所有页面都可以正常工作和渲染，无论选择哪种学科，我也都得到相同的6个结果。我运行了一个打印命令，可以看到objects.filter返回正确的结果，但是这些结果没有出现在下拉菜单中。我感到难过...。有什么建议吗？

我尝试了许多在线教程，并在堆栈交换中检查了几个问题，但没有一个匹配我的问题。我真的很困惑

fieldOptions = Field.objects.filter(discipline_Main=discipline)
print("The available fields are: %s" % fieldOptions)

返回正确的结果：

field_name = forms.ModelChoiceField(queryset=Field.objects.filter(discipline_Main=disciplineID))

仅显示相同的6个结果。

我的模型是：

class Discipline(models.Model):
    #This is the top level category ie: Math, physics, chemistry, biology, history, english, etc
    discipline_name = models.CharField(max_length=50)
    description_text = models.CharField(max_length=200)
    discipline_create_date = models.DateTimeField(default=datetime.now, blank=True)

    def __str__(self):
        return self.discipline_name

class Field(models.Model):
    #This is the level below discipline, example for math would be:
    #Foundations, number systems, logics, etc
    field_name = models.CharField(max_length=50)
    description_text = models.CharField(max_length=200)
    discipline_Main = models.ForeignKey(Discipline, on_delete=models.PROTECT, related_name='discipline_Main', null=True)
    create_date = models.DateTimeField('Field Creation Date', default=datetime.now, blank=True)

    def __str__(self):
        return self.field_name

我的观点是：

def pullDiscipline(request):
    if request.method == 'POST':
        print("If statement has run")
        form = forms.DisciplineForm(request.POST)

        if form.is_valid():
            print("Form was valid, what now?")
            print(request.POST['discipline_name'])
            discipline = Discipline.objects.get(discipline_name=request.POST['discipline_name'])
            print("The current discipline is: %s" % discipline)
            context = discipline.id
            print("The id for chemistry is: %s" % context)
            return redirect('/assessment/pullField/%s' % context)
    else:
        print("Else statement run")
        form = forms.DisciplineForm(request.POST)
    return render(request, "assessment/pullDiscipline.html", {'form' : form})


def pullField(request, pk):
    disciplineID = pk
    form = forms.FieldForm(disciplineID, request.POST)
    return render(request, "assessment/pullField.html", {'form' : form})

我的表格是：

class FieldForm(ModelForm):

    def __init__(self,disciplineID,*args,**kwargs):
        print("Field form is called")
        print("THe disciplineID is: %s" % disciplineID)
        discipline = Discipline.objects.get(id=disciplineID)
        print("The name of the discipline is: %s" % discipline)
        fieldOptions = Field.objects.filter(discipline_Main=discipline)
        print("The available fields are: %s" % fieldOptions)
        #Fetches only requested options from Field model to populate the drop down
        super(FieldForm,self).__init__(*args, **kwargs)
        field_name = forms.ModelChoiceField(queryset=Field.objects.filter(discipline_Main=disciplineID))

    class Meta:
        model = Field
        fields = ['field_name']

最后我的模板文件是：

<form id="pullField" method="POST" >
{% csrf_token %}
{{form.field_name}}
<br>
<button type="submit" class="btn btn-default">Submit</button>
</form>

我没有收到任何错误消息，似乎一切正常，问题是即使打印行在控制台中显示了正确的查询集，我在第二个下拉菜单中也只能得到相同的6个结果。任何建议表示赞赏。

Answer 1

更改表单中的这一行：

field_name = forms.ModelChoiceField(queryset=Field.objects.filter(discipline_Main=disciplineID))

收件人：

self.fields['field_name'].queryset = Field.objects.filter(discipline_Main=disciplineID)

此外，当您不进行POST请求时，请勿在表单实例启动时将request.POST作为参数传递。例如：

def pullField(request, pk):  # Please use Pascal Case when defining ClassName
    disciplineID = pk
    form = forms.FieldForm(disciplineID)  # removed request.POST because its a GET request
    return render(request, "assessment/pullField.html", {'form' : form})

def pullDiscipline(request):  # Please use Pascal Case when defining ClassName
    if request.method == 'POST':
        # POST related codes
    else:
        form = forms.DisciplineForm()  # removed request.POST
    return render(request, "assessment/pullDiscipline.html", {'form' : form})

Django ModelChoiceField queryset不管输入如何，都返回相同的结果

1 个答案: