在ModelForm中保存ModelMultipleChoiceField时如何解决ValueError?

问题描述

我的模型.py:

class RelayAddress(models.Model):
    id = models.AutoField(primary_key=True,default=0)
    sister_relay_relation = models.ManyToManyField('self', through='RelaySisterRelation',symmetrical=False)

    def save(self, *args, **kwargs):
        self.update_time = int(time.time())
        super(RelayAddress,self).save(*args, **kwargs)

class RelaySisterRelation(models.Model):
    id = models.AutoField(primary_key=True,default=0)
    relay = models.ForeignKey(RelayAddress,related_name="relay")
    sister_relay = models.ForeignKey(RelayAddress,related_name="sister_relay")

我的管理员.py

class RelaySisterRelationForm(forms.ModelForm):
    relay=forms.ModelMultipleChoiceField(label=u'relay',widget=forms.CheckboxSelectMultiple(),queryset=RelayAddress.objects.all())
    sister_relay=forms.ModelMultipleChoiceField(label=u'sister_relay',widget=forms.CheckboxSelectMultiple(),queryset=RelayAddress.objects.all())

    def save(self, *args, **kwargs):
        return super(RelaySisterRelationForm, self).save(*args,**kwargs)

我的view.py为null，然后出现ValueError:

And my view.py is null, then I get a ValueError:

Cannot assign "[<RelayAddress: RelayAddress object>]": "RelaySisterRelation.relay" must be a "RelayAddress" instance.

以及如何解决此问题.

推荐答案

RelaySisterRelation.relay 是 RelayAddress 的外键，这意味着它只能存储对一个的引用> RelayAddress ，但是您的 RelaySisterRelationForm.relay 使用 ModelMultipleChoiceField (用于多对多关系)，因此返回(可能为空) RelayAddress 实例.

RelaySisterRelation.relay is a ForeignKey to RelayAddress meaning it can only store a references to one RelayAddress but your RelaySisterRelationForm.relay uses ModelMultipleChoiceField which is for many-to-many relations so returns a (potentially empty) list of RelayAddress instances.

这篇关于在ModelForm中保存ModelMultipleChoiceField时如何解决ValueError?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！