-Django-在创建数据库的新对象时“无法分配”u 'Wing'“：”Truck.MODEL“必须是”MODEL“实例-Java 学习之路

models.py：

class MODEL(models.Model):
    ModelName = models.CharField(max_length = 128, unique = True)
    URL_Slug = models.SlugField(unique = True)
    ...

class Maker(models.Model):
    maker = models.CharField(max_length = 128, unique = True)
    URL_Slug = models.SlugField(unique = True)
    ...
class Truck(models.Model):
    MODEL = models.ForeignKey(MODEL)
    CarID = models.CharField(max_length = 10, unique = True, null = False)
    Maker = models.ForeignKey(Maker)   
    year = models.IntegerField(default = 0)
    def __unicode__(self):
        return self.CarID

forms.py：

class MODELForm(forms.ModelForm):
    ModelName = forms.CharField(max_length = 128, help_text = 'Enter the NEW model name')
    URL_Slug = forms.SlugField(widget = forms.HiddenInput(), required = False)

    class Meta:
        model = MODEL
        fields = ('ModelName', )

class MakerForm(forms.ModelForm):
    maker = forms.CharField(max_length = 128, help_text = 'Enter the NEW maker')
    URL_Slug = forms.SlugField(widget = forms.HiddenInput(), required = False)

    class Meta:
        model = Maker
        fields = ('maker', )

class TruckForm(forms.ModelForm):
    MODEL = forms.CharField(max_length = 128, help_text = 'Enter the NEW model name')
    CarID = forms.CharField(max_length = 10, help_text = 'Enter the NEW truck ID')
    Maker = forms.CharField(max_length = 128, help_text = 'Enter the NEW maker')   
    year = forms.IntegerField(help_text = 'Enter the year of production')

    class Meta:
        model = Truck
        fields = ('MODEL', 'CarID', 'Maker', 'year')

views.py：

def add_Truck(request):
    form = TruckForm()

    if request.method == 'POST':
        form = TruckForm(request.POST)
        if form.is_valid():
            form.save(commit = True)
            return index(request)

        else:
            print(form.errors)
    return render(request, 'APP/addTruck.html', {'form': form})

HTML文件：

<!DOCTYPE html>
<html>
    <body>
        <div>
            <form id = "Truck" method = "post" action = "/APP/NewTruck/">
                {%csrf_token%}
                {% for field in form.visible_fields %}
                    {{field.errors}}
                    {{field.help_text}}
                    {{field}}

                {% endfor %}
                <input type = "submit" name = "submit" value = "Create Truck">
            </form>
        </div>
    </body>
</html>

我试图在addTruck.html中创建一个新对象，我的客户因为MODEL和Maker是外键，在创建Truck对象时，MODEL和Maker字段也应该是对象 .

追溯：

这是终端Macbook的Traceback：

[07 / Aug / 2017 09:14:04]“GET / APP / NewTruck / HTTP / 1.1”200 1240内部服务器错误：/ APP / NewTruck / Traceback（最近一次调用最后一次）：文件“/ Library / Frameworks / Python.framework / Versions / 2.7 / lib / python2.7 / site-packages / django / core / handlers / exception.py“，第39行，内部响应= get_response（请求）文件”/Library/Frameworks/Python.framework /Versions/2.7/lib/python2.7/site-packages/django/core/handlers/base.py“，第187行，在_get_response response = self.process_exception_by_middleware（e，request）File”/ Library / Frameworks / Python . framework / Versions / 2.7 / lib / python2.7 / site-packages / django / core / handlers / base.py“，第185行，在_get_response response = wrapped_callback（request，* callback_args，** callback_kwargs）File”/ Users / apple / WebWorkshop / TKTrading / APP / views.py“，第88行，在add_Truck中，如果form.is_valid（）：文件”/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/ django / forms / forms.py“，第169行，在is_valid中返回self.is_bound而不是self.errors文件”/ Library / Frameworks / Python.framework / Versions / 2.7 / lib / python2.7 / site-packages / django / forms / forms.py“，第161行，错误self.full_clean（）文件”/ Library / Frameworks / Python . framework / Versions / 2.7 / lib / python2.7 / site-packages / django / forms / forms.py“，第372行，在full_clean self._post_clean（）文件”/Library/Frameworks/Python.framework/Versions/2.7/ lib / python2.7 / site-packages / django / forms / models.py“，第388行，在_post_clean self.instance = construct_instance（self，self.instance，opts.fields，opts.exclude）文件”/ Library / Frameworks /Python.framework/Versions/2.7/lib/python2.7/site-packages/django/forms/models.py“，第60行，在construct_instance f.save_form_data（实例，cleaning_data [f.name]）文件”/ Library /Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/models/fields/init.py“，第833行，在save_form_data setattr（instance，self.name，data）文件中“/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/models/fields/related_descrip tors.py“，第211行，在set self.field.remote_field.model._meta.object_name，ValueError：无法分配”u'Wing'“：”Truck.MODEL“必须是”MODEL“实例 . [07 / Aug / 2017 09:14:42]“POST / APP / NewTruck / HTTP / 1.1”500 93290

1 回答

1
在你的 TruckForm 中，
```
MODEL = forms.CharField(max_length = 128, help_text = 'Enter the NEW model name')
```
在你的模特中，
```
MODEL = models.ForeignKey(MODEL)
```
ForeignKey fields need to be instances of the corresponding models, rather than plain text . 错误消息非常具体 . 在您的情况下，如果您想每次为新卡车创建新模型，您可能需要覆盖 save() 的 save() 方法，原因有正当理由 . 或者如果你想从现有的 MODELs 中选择一个模型，你可以让Django使用该字段的默认选择小部件，或者你也可以通过定义一个自定义小部件来覆盖它 .
```
MODEL = forms.ModelChoiceField(queryset=MODEL.objects.all())
#something like this.
```
回复于 2024-04-28T06:52:56+08:00

-Django-在创建数据库的新对象时“无法分配”u 'Wing'“：”Truck.MODEL“必须是”MODEL“实例

1 回答

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