Django 多对多模型验证 [英] Django ManyToMany model validation

问题描述

我有一个类似这个模型的 ManyToManyField 模型(模型 Word 也有一种语言):

I have a model with a ManyToManyField similar to this one (the model Word has a language, too):

class Sentence(models.Model):
    words = models.ManyToManyField(Word)
    language = models.ForeignKey(Language)
    def clean(self):
        for word in self.words.all():
            if word.language_id != self.language_id:
                raise ValidationError('One of the words has a false language')

当尝试添加一个新句子时(例如通过 django admin)，我得到 'Sentence' 实例需要有一个主键值才能使用多对多关系.这意味着我无法在保存之前访问 self.words，但这正是我想要做的.有什么办法可以解决这个问题，这样你就可以验证这个模型吗?我真的很想直接验证模型的字段.

When trying to add a new sentence (e.g. through django admin) I get 'Sentence' instance needs to have a primary key value before a many-to-many relationship can be used. This means I can't access self.words before saving it, but this is exactly what I'm trying to do. Is there any way to work around this so you can validate this model nevertheless? I really want to directly validate the model's fields.

我发现了很多关于这个异常的问题，但我找不到解决我的问题的帮助.我将不胜感激任何建议！

I found many questions concerning this exception, but I couldn't find help for my problem. I would appreciate any suggestions!

推荐答案

无法在模型的 clean 方法中进行此验证，但您可以创建一个模型表单来验证选择词.

It is not possible to do this validation in the model's clean method, but you can create a model form which can validate the choice of words.

from django import forms

class SentenceForm(forms.ModelForm):
    class Meta:
        model = Sentence
        fields = ['words', 'language']

    def clean(self):
        """
        Checks that all the words belong to the sentence's language.
        """
        words = self.cleaned_data.get('words')
        language = self.cleaned_data.get('language')
        if language and words:
            # only check the words if the language is valid
            for word in words:
                if words.language != language:
                    raise ValidationError("The word %s has a different language" % word)
        return self.cleaned_data

然后您可以自定义您的 Sentence 模型管理类，以在 Django 管理中使用您的表单.

You can then customise your Sentence model admin class, to use your form in the Django admin.

class SentenceAdmin(admin.ModelAdmin):
    form = SentenceForm

admin.register(Sentence, SentenceAdmin)

这篇关于Django 多对多模型验证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IT屋！