Python Django REST Framework 序列化程序字段 required=false

Django REST Framework serializer field required=false

提问by James Lin

from the documentation:

从文档：

read_only Set this to True to ensure that the field is used when serializing a representation, but is not used when updating an instance during deserialization.

Defaults to False

required Normally an error will be raised if a field is not supplied during deserialization. Set to false if this field is not required to be present during deserialization.

Defaults to True.

read_only 将此设置为 True 以确保在序列化表示时使用该字段，但在反序列化期间更新实例时不使用该字段。

默认为假

required 通常，如果在反序列化期间未提供字段，则会引发错误。如果在反序列化期间不需要此字段存在，则设置为 false。

默认为真。

So I have a model which has a field that's not nullable but I want it to be populated in the pre_save method, so I have set the field to required=Falsein serializer, but doesn't seem to work. I am still getting error when saving the record.

所以我有一个模型，它有一个不可为空的字段，但我希望它被填充到 pre_save 方法中，所以我已将该字段设置为required=False在序列化程序中，但似乎不起作用。保存记录时仍然出错。

class FavoriteListSerializer(serializers.ModelSerializer):
    owner = serializers.IntegerField(required=False)
    class Meta:
        model = models.FavoriteList

Update: I have added serializer_class = serializers.FavoriteListSerializerto the ViewSet, now instead of getting This field is required, which I think got past the validation but then I am getting This field cannot be null.I have checked the pre_save method is not being executed, any ideas?

更新：我已经添加serializer_class = serializers.FavoriteListSerializer到 ViewSet，而不是现在This field is required，我认为它已经通过了验证，但后来我This field cannot be null.检查了 pre_save 方法没有被执行，有什么想法吗？

采纳答案by Kevin Stone

Yeah, I ran into this issue at some point as well. You need to also update the validation exclusions.

是的，我在某些时候也遇到了这个问题。您还需要更新验证排除项。

class FavoriteListSerializer(serializers.ModelSerializer):
    owner = serializers.IntegerField(required=False)
    class Meta:
        model = models.FavoriteList

    def get_validation_exclusions(self):
        exclusions = super(FavoriteListSerializer, self).get_validation_exclusions()
        return exclusions + ['owner']

回答by Pankaj Singhal

Late Entry to this thread. This issue was fixed in django-rest-framework 2.3.13. Here is the link of the PR.

延迟进入此线程。此问题已在django-rest-framework 2.3.13 中修复。这是PR的链接。

You use it like this in your case:

在您的情况下，您可以像这样使用它：

    class Meta:
        model = models.FavoriteList
        optional_fields = ['owner', ]

回答by Wtower

In case somebody lands here with a similar issue, pay attention to the following attributes along with required:

如果有人遇到类似问题，请注意以下属性以及required：

allow_blank:

允许空白：

If set to Truethen the empty string should be considered a valid value.

如果设置为True空字符串，则应将其视为有效值。

allow_null:

允许_空：

Normally an error will be raised if Noneis passed to a serializer field.

通常，如果None传递给序列化程序字段，则会引发错误。

required:

要求：

Normally an error will be raised if a field is not supplied during deserialization.

通常，如果在反序列化期间未提供字段，则会引发错误。

I was straggling to figure out why I was getting a validation error with required=Falsewhere I had missed the allow_nullattribute.

我一直在努力弄清楚为什么我会required=False在我错过allow_null属性的地方收到验证错误。

回答by validname

I suppose method .get_validation_exclusions() is now removed. I did not found it in ModelSerializer docand it did not execute after override (djangorestframework==3.8.2). And i am not the only one facing this problem.

我想方法 .get_validation_exclusions() 现在已被删除。我没有在ModelSerializer 文档中找到它，并且它在覆盖后没有执行（djangorestframework==3.8.2）。而且我不是唯一面临这个问题的人。

My solution is to just add default value for field which i want to be non-required. It supposed to be fine specifically for situations with pre_save:

我的解决方案是只为我希望不需要的字段添加默认值。专门用于 pre_save 的情况应该没问题：

class FavoriteListSerializer(serializers.ModelSerializer):
    owner = serializers.IntegerField(default='')
    class Meta:
        model = models.FavoriteList

You also have to keep in mind that using drf serializers with pre_save signals may cause implicit behavour(i did not check, but it seems to be logical):

您还必须记住，使用带有 pre_save 信号的 drf 序列化程序可能会导致隐式行为（我没有检查，但似乎是合乎逻辑的）：

pre_saveis calledon pre object save (incredible) which (probably) means after serializer validation.

pre_save在 pre object save (incredible) 这（可能）意味着在序列化程序验证之后调用。

回答by Vaghinak

If you have unique_together constraint on one of the fields you are trying to set required=Falseyou need to set validators=[]in serializers Meta like

如果您对要设置的字段之一具有 unique_together 约束，则required=False需要validators=[]在序列化器 Meta 中进行设置，例如

class FavoriteListSerializer(serializers.ModelSerializer):
    owner = serializers.IntegerField(required=False)
    class Meta:
        model = models.FavoriteList
        validators = []

Here is the original answer

这是原始答案