Kann nicht zuweisen muss eine Instanz sein. Django

Question

Ich habe versucht, ein Django-Projekt zu erstellen, mit dem Benutzer und diese Benutzer Titel von Büchern hinzufügen können, die sie erstellt haben. Aber jedes Mal, gebe ich einen Buchtitel (nicht auf der Admin-Seite) bekomme ich diesen Fehler

Cannot assign "u'Hello Wold'": "Scripter.title" must be a "Book" instance. 

models.py

from django.db import models 
from django.contrib.auth.models import User 

class Book(models.Model): 
    script_title = models.CharField(max_length=100) 

    def __unicode__(self): 
     return self.script_title 

class Scripter(models.Model): 
    user = models.OneToOneField(User) 
    name = models.CharField(max_length=30) 
    title = models.ForeignKey(Book, null=True, blank=True, default=None) 

    def __unicode__(self): 
     return self.name 

forms.py

from django import forms 
from django.contrib.auth.models import User 
from django.forms import ModelForm 
from scripters.models import Scripter#, Book 

class RegistrationForm(ModelForm): 
    username = forms.CharField(label=(u'User Name')) 
    email = forms.EmailField(label=(u'Email Address')) 
    password = forms.CharField(label=(u'Password'), widget=forms.PasswordInput(render_value=False)) 
    password1 = forms.CharField(label=(u'Verify Password'), widget=forms.PasswordInput(render_value=False)) 

    class Meta: 
     model = Scripter 
     exclude = ('user','title') 

    def clean_username(self): 
     username = self.cleaned_data['username'] 
     try: 
      User.objects.get(username=username) 
     except User.DoesNotExist: 
      return username 
     raise forms.ValidationError("User Name has been taken!") 

    def clean(self): 
     if self.cleaned_data['password'] != self.cleaned_data['password1']: 
      raise forms.ValidationError("The passwords did not match") 
     else: 
      return self.cleaned_data 

class LoginForm(forms.Form): 
    username = forms.CharField(label=(u'Username')) 
    password = forms.CharField(label=(u'Password'), widget=forms.PasswordInput(render_value=False)) 

class CreateScript(ModelForm): 
    title = forms.CharField(label=(u'Script Title')) 

    class Meta: 
     model = Scripter 
     exclude = ('user','name',) 

    def clean_title(self): 
     title = self.cleaned_data['title'] 
     return title 

views.py

from django.http import HttpResponseRedirect 
from django.contrib.auth.models import User 
from django.contrib.auth.decorators import login_required 
from django.shortcuts import render_to_response 
from django.template import RequestContext 
from scripters.forms import RegistrationForm, LoginForm, CreateScript 
from scripters.models import Scripter, Book 
from django.contrib.auth import authenticate, login, logout 

def ScripterRegistration(request): 
    if request.user.is_authenticated(): 
     return HttpResponseRedirect('/profile/') 
    if request.method =='POST': 
     form = RegistrationForm(request.POST) 
     if form.is_valid(): 
      user = User.objects.create_user(username=form.cleaned_data['username'], 
       email = form.cleaned_data['email'], 
       password = form.cleaned_data['password'] 
      ) 
      user.save() 
      scripter = Scripter(user=user, name=form.cleaned_data['name']) 
      scripter.save() 

      return HttpResponseRedirect('/profile/') 
     else: 
      return render_to_response('index.html', {'form': form}, context_instance=RequestContext(request)) 
    else: 
     form = RegistrationForm() 
     context = {'form': form} 
     return render_to_response('index.html', context, context_instance=RequestContext(request)) 

@login_required 
def Profile(request): 
    if not request.user.is_authenticated(): 
     return HttpResponseRedirect('/login/') 
    Scripter = request.user.get_profile() 

    context = {'Scripter': Scripter, 'Book': Book} 
    return render_to_response('profile.html', context, context_instance=RequestContext(request)) 

def LoginRequest(request): 
    if request.user.is_authenticated(): 
     return HttpResponseRedirect('/profile/') 
    if request.method == 'POST': 
     submit = LoginForm(request.POST) 
     if submit.is_valid(): 
      username = submit.cleaned_data['username'] 
      password = submit.cleaned_data['password'] 
      scripter = authenticate(username=username, password=password) 
      if scripter is not None: 
       login(request, scripter) 
       return HttpResponseRedirect('/profile/') 
      else: 
       return HttpResponseRedirect('/login/') 
    else: 
     submit = LoginForm() 
     context = {'submit': submit} 
     return render_to_response('login.html',context, context_instance=RequestContext(request)) 

def LogoutRequest(request): 
    logout(request) 
    return HttpResponseRedirect('/login/') 

@login_required 
def NewScript(request): 
    if not request.user.is_authenticated(): 
     return HttpResponseRedirect('/login/') 
    if request.method =='POST': 
     title_form = CreateScript(request.POST) 
     if title_form.is_valid(): 
      new_script = Book.objects.get_or_create(
       script_title = title_form.cleaned_data['title'] 
      ) 
      new_script.save() 
      script = Book(script_title=title_form.cleaned_data['title']) 
      script.save() 
      return HttpResponseRedirect('/edit/') 
     else: 
      return render_to_response('NewScript.html', {'title_form': title_form}, context_instance=RequestContext(request)) 
    else: 
     title_form = CreateScript() 
     context = {'title_form': title_form} 
     return render_to_response('NewScript.html', context, context_instance=RequestContext(request)) 

Answer 1

Natürlich. Nicht sicher, wo die Verwirrung hier ist. Scripter.title ist ein Fremdschlüssel zu Book, so müssen Sie es eine tatsächliche Book geben, keine Zeichenfolge.

Answer 2

Erstens, während dies nicht Ihre Frage ist, glaube ich, dass Sie etwas verpasst haben. Wenn ich richtig verstehe, wünschen Sie Scripters, mehrere Bücher zu haben. Nun, mit Ihren Modellen können sie nur ein Buch haben. Wenn ich richtig bin, wie von dem, was Sie erreichen wollen, sollten Sie Ihr Modell eher so aussehen:

class Book(models.Model): 
    script_title = models.CharField(max_length=100) 
    scripter = models.ForeignKey(Scripter)#A book "remembers" who wrote it 

    def __unicode__(self): 
    return self.script_title 

class Scripter(models.Model): 
    user = models.OneToOneField(User) 
    name = models.CharField(max_length=30) 
    #Scripter can write multiple books, can't he? So the next line is removed, 
    #replaced by an extra line in Book class 

    # title = models.ForeignKey(Book, null=True, blank=True, default=None) 

Dann würden Sie Scripter Bücher wie diese zugreifen:

scripter = Scripter.objects.get(name="joshua") 
books = scripter.book_set.all() #all books written by joshua 

Was Ihre Frage, in der aktuellen Form, müssen Sie so etwas wie dies zu tun:

book = Book.objects.get(script_title="some_title") 
scripter.title = book 

Aber wie ich schon sagte, müssen Sie Ihre Modellstruktur ändern, so werden Sie eher tun:

scripter = Scripter.objects.get(name="joshua") 
book = Book.objects.Create(script_title="some title",scripter=scripter)