Django Rest Framework用户注册时出现KeyError 'password'问题排查

问题现象 #

在Postman测试user_app的注册API时触发以下错误：

KeyError at /account/register/
'password'
请求方法：POST
请求URL：http://127.0.0.1:8010/account/register/
Django版本：4.1
异常类型：KeyError
异常值：'password'
异常位置：C:...\watchmate\user_app\api\serializers.py第28行save方法中
触发视图：user_app.api.views.registration_view

测试参数：

• username: example
• email: example@xyz.com
• password: example123
• password2: example12

预期返回{'error':'password2 is not same as password!'}，但实际触发KeyError。

相关代码 #

视图文件（user_app.api.views.py） #

from rest_framework.decorators import api_view
from user_app.api.serializers import RegistrationSerializer
from rest_framework.response import Response

@api_view(['POST',])
def registration_view(request):
    if request.method == 'POST':
        serializer = RegistrationSerializer(data=request.data)
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data)

序列化器文件（watchmate\user_app\api\serializers.py） #

from django.contrib.auth.models import User
from rest_framework import serializers

class RegistrationSerializer(serializers.Serializer):
    password2 = serializers.CharField(style={'input_type':'password'}, write_only=True)

    class Meta: 
        model = User
        field = ['username', 'email', 'password', 'password2']
        extra_kwargs = {'password': { 'write_only':True}}

    def save(self):
        password = self.validated_data['password']
        password2 = self.validated_data['password2']
        if password != password2:
            raise serializers.ValidationError({'error':'Password is not matching!'})

问题分析与修复 #

1. KeyError('password')的核心原因 #

序列化器Meta类中的字段定义存在拼写错误：field应该是复数形式fields。因为这个错误，DRF无法识别password字段，不会将其纳入验证流程，导致validated_data中没有password键，触发KeyError。

2. 密码不匹配提示与功能缺失问题 #

除了拼写错误，当前代码还有两个关键问题：

• 自定义save方法未实现用户创建逻辑，即使密码匹配也无法生成新用户
• 密码不匹配的错误提示文本与预期不一致

完整修复后的序列化器代码 #

from django.contrib.auth.models import User
from rest_framework import serializers

class RegistrationSerializer(serializers.ModelSerializer):
    password2 = serializers.CharField(style={'input_type':'password'}, write_only=True)

    class Meta: 
        model = User
        fields = ['username', 'email', 'password', 'password2']  # 修正为复数fields
        extra_kwargs = {'password': { 'write_only':True}}

    def validate(self, attrs):
        # 将密码校验逻辑放在DRF推荐的validate方法中
        password = attrs.get('password')
        password2 = attrs.get('password2')
        if password != password2:
            raise serializers.ValidationError({'error':'password2 is not same as password!'})
        return attrs

    def save(self):
        # 实现用户创建及密码加密逻辑
        user = User(
            username=self.validated_data['username'],
            email=self.validated_data['email']
        )
        user.set_password(self.validated_data['password'])  # 使用Django内置密码加密
        user.save()
        return user

视图优化：补充错误响应 #

原视图未处理序列化器验证失败的场景，建议补充：

@api_view(['POST',])
def registration_view(request):
    if request.method == 'POST':
        serializer = RegistrationSerializer(data=request.data)
        data = {}
        if serializer.is_valid():
            user = serializer.save()
            data['response'] = "Registration successful!"
            data['username'] = user.username
            data['email'] = user.email
        else:
            data = serializer.errors  # 返回验证错误信息
        return Response(data)

修复后效果 #

当password与password2不匹配时，Postman会返回预期的错误：

{"error":"password2 is not same as password!"}

KeyError问题完全解决，密码匹配时会成功创建用户并返回注册成功信息。

内容的提问来源于stack exchange，提问作者Swati Mishra