class User(db.Model):
    __tablename__ = 'users'
    id = db.Column(db.Integer, primary_key=True)
    email = db.Column(db.String(64), unique=True, index=True)
    username = db.Column(db.String(64), unique=True, index=True)
    role_id = db.Column(db.Integer, db.ForeignKey('roles.id'))
    password_hash = db.Column(db.String(128))
    confirmed = db.Column(db.Boolean, default=False)
    name = db.Column(db.String(64))
    location = db.Column(db.String(64))
    about_me = db.Column(db.Text())
    member_since = db.Column(db.DateTime(), default=datetime.utcnow)
    last_seen = db.Column(db.DateTime(), default=datetime.utcnow)
    avatar_hash = db.Column(db.String(32))
    posts = db.relationship('Post', backref='author', lazy='dynamic')
    comments = db.relationship('Comment', backref='author', lazy='dynamic')


    def to_json(self):
        json_user = {
            'url': url_for('api.get_post', id=self.id, _external=True),
            'username': self.username,
            'member_since': self.member_since,
            'last_seen': self.last_seen,
            'posts': url_for('api.get_user_posts', id=self.id, _external=True),
            'post_count': self.posts.count()
        }
        return json_user

class Post(db.Model):
    __tablename__ = 'posts'
    id = db.Column(db.Integer, primary_key=True)
    body = db.Column(db.Text)
    body_html = db.Column(db.Text)
    timestamp = db.Column(db.DateTime, index=True, default=datetime.utcnow)
    author_id = db.Column(db.Integer, db.ForeignKey('users.id'))
    comments = db.relationship('Comment', backref='post', lazy='dynamic')

    def to_json(self):
        json_post = {
            'url': url_for('api.get_post', id=self.id, _external=True),
            'body': self.body,
            'body_html': self.body_html,
            'timestamp': self.timestamp,
            'author': url_for('api.get_user', id=self.author_id,
                              _external=True),
            'comments': url_for('api.get_post_comments', id=self.id,
                                _external=True),
            'comment_count': self.comments.count()
        }
        return json_post

2个类的定义如上,然后,假设现在需要获取设计两个接口：

• 获取某个文章详细信息的接口。
• 获取某个人发表的文章详细信息。
  我看到很多教程都是类似这样设计的：

 @api.route('/posts/<int:id>')
def get_post(id):
    post = Post.query.get_or_404(id)
    return jsonify(post.to_json())

@api.route('/users/<int:id>/posts/')
def get_user_posts(id):
    user = User.query.get_or_404(id)
    page = request.args.get('page', 1, type=int)
    pagination = user.posts.order_by(Post.timestamp.desc()).paginate(
        page, per_page=current_app.config['FLASKY_POSTS_PER_PAGE'],
        error_out=False)
    posts = pagination.items
    prev = None
    if pagination.has_prev:
        prev = url_for('api.get_posts', page=page-1, _external=True)
    next = None
    if pagination.has_next:
        next = url_for('api.get_posts', page=page+1, _external=True)
    return jsonify({
        'posts': [post.to_json() for post in posts],
        'prev': prev,
        'next': next,
        'count': pagination.total
    })

对于接口返回的数据我有几个疑问:
1:为什么很多详细信息都是返回URL而不是实体。
比如:Class User类的to_json()方法为什么不像这样设计?

 def to_json(self):
    json_user = {
        'url': url_for('api.get_post', id=self.id, _external=True),
        'username': self.username,
        'member_since': self.member_since,
        'last_seen': self.last_seen,
        'posts': [post.to_json() for post in self.posts],
        'post_count': self.posts.count()
    }
    return json_user

2:如果要返回实体信息要怎么操作好?
3:我在github中看到很多flsk开源的项目，里面序列化或者反序列化都是用类似上面to_json, to_dict实现的，包括很多教程都是这样设计的。这种方法，个人觉得对于Model有几十个属性就感觉很无力，有什么好的办法?