django restframework：获取 NotImplementedError

Question

我收到 NotimplementError。我正在研究 Django restframework 身份验证和权限。我可以通过管理面板输入数据，但是当涉及到序列化程序时，我收到了这个错误。

下面是错误报告：

NotImplementedError at /api/tasks/

Field.to_representation() must be implemented for field owner. If you do not need to support write operations you probably want to subclass `ReadOnlyField` instead.

Request Method:     GET
Request URL:    http://127.0.0.1:8000/api/tasks/
Django Version:     1.9
Exception Type:     NotImplementedError
Exception Value:    

Field.to_representation() must be implemented for field owner. If you do not need to support write operations you probably want to subclass `ReadOnlyField` instead.

Exception Location:     /home/graymatter/test/bookenv/local/lib/python2.7/site-packages/rest_framework/fields.py in to_representation, line 529
Python Executable:  /home/graymatter/test/bookenv/bin/python
Python Version:     2.7.6
Python Path:    

['/home/graymatter/test/todo',
 '/home/graymatter/test/bookenv/lib/python2.7',
 '/home/graymatter/test/bookenv/lib/python2.7/plat-x86_64-linux-gnu',
 '/home/graymatter/test/bookenv/lib/python2.7/lib-tk',
 '/home/graymatter/test/bookenv/lib/python2.7/lib-old',
 '/home/graymatter/test/bookenv/lib/python2.7/lib-dynload',
 '/usr/lib/python2.7',
 '/usr/lib/python2.7/plat-x86_64-linux-gnu',
 '/usr/lib/python2.7/lib-tk',
 '/home/graymatter/test/bookenv/local/lib/python2.7/site-packages']

Server time:    Tue, 8 Mar 2016 09:03:24 +0000

这是我的 serializers.py

from rest_framework import serializers

from .models import Task


class TaskSerializers(serializers.ModelSerializer):
    owner = serializers.Field(source='owner.username')

    class Meta:
        model = Task
        fields = ('title', 'desc', 'completed', 'owner')

视图.py：

from django.shortcuts import render
from rest_framework import generics
from rest_framework import mixins

from .models import Task
from .serializers import TaskSerializers
from .permissions import IsOwnerOrReadOnly


# Create your views here.
class TaskMixin(object):
    queryset = Task.objects.all()
    serializer_class = TaskSerializers
    permission_classes = (IsOwnerOrReadOnly,)

    def pre_save(self, obj):
        obj.owner = self.request.user



class TaskDetail(TaskMixin, generics.RetrieveUpdateAPIView):
    pass


class TaskList(TaskMixin, generics.ListCreateAPIView):
    pass

下面是models.py

from __future__ import unicode_literals

from django.db import models


# Create your models here.

class Task(models.Model):
    owner = models.ForeignKey('auth.user', related_name='tasks')
    completed = models.BooleanField(default=False, verbose_name='Completed')
    title = models.CharField(max_length=200, verbose_name='Title')
    desc = models.TextField(verbose_name='Description')

    def __unicode__(self):
        return self.title

下面是permissions.py

from rest_framework.permissions import BasePermission, SAFE_METHODS


class IsOwnerOrReadOnly(BasePermission):
    def has_object_permission(self, request, view, obj):
        if request.method in SAFE_METHODS:
            return True
        return obj.owner == request.user

我是 Django 和 rest 框架的初学者。我正在关注本教程。现在我被困在这里。请帮忙。

谢谢！！！！

Answer 1

确实，变

owner = serializers.Field(source='owner.username')

到

owner = serializers.ReadOnlyField(source='owner.username')

有诀窍

Answer 2

也许教程已经过时了。就像错误消息所示，您应该将owner序列化器中的字段更改为ReadOnlyField（文档）