我在將用戶（外鍵）傳遞到提交的表單時遇到問題。這是模型的樣子：from django.db import modelsfrom person.models import UserProfilefrom django.urls import reversefrom django.conf import settingsfrom django.contrib.auth import get_user_modelfrom django.contrib.auth.models import Userfrom django.db.models import signalsUser = get_user_model()# Create your models here.class UserPost(models.Model, Activity):    author = models.ForeignKey(User, on_delete=models.CASCADE, related_name='userpostauthor')    content = models.TextField(max_length=2000, blank=True, null=True)    postvideo = models.FileField(upload_to='UserPost/postvideo', blank=True, null=True)    postPicture = models.FileField(upload_to='UserPost/postpicture', blank=True, null=True)    created_at = models.DateTimeField(auto_now_add=True)這是我的 views.py 形式：class TimelineView(CreateView):    fields= ['content', 'postvideo', 'postPicture']    model = UserPost    success_url = reverse_lazy('timeline_feed')    template_name = 'main/timeline.html'    def form_valid(self, form):        form.instance.user = self.request.user        return super(TimelineView, self).form_valid(form)    def get_context_data(self, form=None):        context = super(TimelineView, self).get_context_data()當我嘗試提交表單時會出現(xiàn)此錯誤：“author_id”列中 /timeline/ 空值處的 IntegrityError 違反了非空約束詳細信息：失敗行包含 (20, , , , 2020-07-14 20:43:53.631628+00, null)。請求方法：POST 請求 URL： http ://127.0.0.1:8000/timeline/ Django 版本：2.2.12 異常類型：IntegrityError 異常值：“author_id”列中的空值違反了非空約束 詳細信息：失敗行包含 ( 20, , , , 2020-07-14 20:43:53.631628+00, 空）。顯然我做錯了什么。解決此問題的最佳方法是什么？