解决

Question

帖子表：

class Post(UserMixin,db.Model):
    __tablename__ = "posts"
    id = db.Column(db.Integer,primary_key= True)
    timestamp = db.Column(db.String(20),index = True)
    author = db.Column(db.Integer,db.ForeignKey("users.id"))
    post = db.Column(db.String(500),index = True)
    comments = db.relationship("Comment",backref = "post_id", lazy = "joined")

评论表：

class Comment(UserMixin,db.Model):
    __tablename__ = "comments"
    id  = db.Column(db.Integer,primary_key = True)
    comment_author_id = db.Column(db.Integer,db.ForeignKey("users.id"))
    id_of_post = db.Column(db.Integer,db.ForeignKey("posts.id"))
    timestamp = db.Column(db.String(60),index = True)
    comment = db.Column(db.String(500),index = True)
    comment_replies = db.relationship("Reply",backref = "comment_id",lazy = "dynamic")

用户表：

class User(UserMixin,db.Model):
    __tablename__ = "users"
    id = db.Column(db.Integer,primary_key = True)
    username = db.Column(db.String(60),unique = True)
    first_name = db.Column(db.String(60),index =  True)
    last_name = db.Column(db.String(60))
    password = db.Column(db.String(100))
    followed = db.relationship("Follow",foreign_keys = [Follow.followed_id],backref = db.backref("follower",lazy = "joined"),lazy = "dynamic")
    follower = db.relationship("Follow",foreign_keys = [Follow.follower_id],backref = db.backref("followed", lazy = "joined"),lazy = "dynamic")
    prof_pic  =db.Column(db.String(40))
    posts = db.relationship("Post",backref = "post_author", lazy = "joined")
    comments = db.relationship("Comment", backref = "comment_author",lazy = "dynamic")
    replies = db.relationship("Reply",backref = "reply_author",lazy = "dynamic")

所以我试图学习网络开发。因此，为了尝试理解事物，我决定去建立自己的小社交网络。只是为了获得关系数据库，瓶子和web dev的概念和想法

到目前为止一切顺利。用户帖子按降序排列。首先看到最新的帖子。人们可以对这些帖子发表评论，然后就可以了解这些帖子。

帖子以正确的方式排序，但评论不是。它们在正确的帖子上发表了评论，但排序基于users.id 因此，如果我user1并且我对user2's发表评论，我的评论将优先于用户2发布，因为我user1。

那么我们如何在sqlaclchemy中查询？

in pseudocode:

order posts by timestamp in descending order and order comments of post by timestamp in descending order

解决

只需更改

即可解决此问题

posts = db.relationship("Post",backref = "post_author", lazy = "joined")

到

posts = db.relationship("Post",backref = "post_author", lazy = "dynamic")

烧瓶SQLAlchemy的。多级连接和排序

解决

0 个答案: