ModelForm表单 重写初始化方法

一个Course下有N个Lesson
功能需求：每个用户只能看到自己所设置的Course。

models.py

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

class Course(models.Model):    
    user = models.ForeignKey(User,on_delete=models.CASCADE,related_name='course_user')
    title = models.CharField(max_length=200)
    overview = models.TextField()

class Lesson(models.Model):
    user = models.ForeignKey(User,on_delete=models.CASCADE,related_name='lesson_user')
    course = models.ForeignKey(Course,on_delete=models.CASCADE,related_name='lesson')
    title = models.CharField(max_length=200)
    video = models.FileField(upload_to=user_directory_path)    
    description = models.TextField(blank=True)
    created = models.DateTimeField(auto_now_add=True)

forms.py

from django import forms
from .models import Course,Lesson

class CreateLessonForm(forms.ModelForm):
    class Meta:
        model = Lesson
        fields = ['course','title','video','description','attach']
 
    def __init__(self,user,*args,**kwargs):                
        super(CreateLessonForm,self).__init__(*args,**kwargs)    # 先调用父类初始化方法
        self.fields['course'].queryset = Course.objects.filter(user=user)     # 注意这里的queryset

重写_init_()初始化方法，让每个用户只能看到自己所设置的课程标题。
如果没有重写，则是按照fields中的声明，会列出所有用户创建的course。
通过user参数传入当前用户，筛选出当前用户的course值。