from django.db import models
from django.utils import timezone
from article.models import Article
from django.contrib.auth.models import User


class Comment(models.Model):
    parent = models.ForeignKey(
        'self',
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name='children',
    )
    # 评论人
    author = models.ForeignKey(
        User,
        on_delete=models.CASCADE,
        related_name='comments',
    )
    # 文章
    article = models.ForeignKey(
        Article,
        on_delete=models.CASCADE,
        related_name='comments',
    )
    # 评论内容
    content = models.TextField()
    # 评论时间
    created = models.DateTimeField(default=timezone.now)

    class Meta:
        ordering = ['-created']

    def __str__(self):
        # 展示前20个字符
        return self.content[:20]