Database Django Save 方法在try 向表中添加新记录时出错

我在一个视图中有以下代码:

        lp_detail = LearningPathDetail()
        pos_in_path = 1
        lp_detail.lpheader_id = pk

        lesson_ids = request.POST["lesson_ids"].split(",")

        for lesson_id in lesson_ids:
            lp_detail.id = ""
            lp_detail.lesson_id = lesson_id
            lp_detail.pos_in_path = pos_in_path
            lp_detail.save()
            pos_in_path += 1

pk是标题表中的ID，它指向标识与其关联的所有详细信息记录的标题记录.

lesson_ids is a list of DB ids that need to be inserted into the lp_detail table.

What I think the code should do (according to the manual) based on the id being blank (I have also tried setting it to None) is create the record, but instead I get an error:

Field 'id' expected a number but got ''.

以下是LearningPath Detail表的模型:

class LearningPathDetail(models.Model):
    lpheader = models.ForeignKey(LearningPathHeader, on_delete=models.CASCADE)
    lesson = models.ForeignKey(Lesson, on_delete=models.CASCADE, blank=True, null=True)
    pos_in_path = models.IntegerField(default=1)

我不确定我在这里有什么不正确的.