first commit

2026-02-27 10:37:11 +08:00
commit 74f19aad0b
86 changed files with 18642 additions and 0 deletions
--- a/models.py
+++ b/models.py
@@ -0,0 +1,470 @@
+# models.py
+from flask_sqlalchemy import SQLAlchemy
+from datetime import datetime
+import json
+
+db = SQLAlchemy()
+
+# 用户表
+class User(db.Model):
+    id = db.Column(db.Integer, primary_key=True)
+    name = db.Column(db.String(80), nullable=False)
+    email = db.Column(db.String(120), unique=True, nullable=True)
+    phone = db.Column(db.String(20), unique=True, nullable=True)
+    password = db.Column(db.String(128), nullable=False)
+    role = db.Column(db.String(20), default='student')  # admin, teacher, student
+    avatar = db.Column(db.String(200), default='')  # 头像URL
+    is_banned = db.Column(db.Boolean, default=False)
+    completed_exams = db.Column(db.Integer, default=0)  # 已完成并批改的考试次数
+    name_changed_at = db.Column(db.DateTime, nullable=True)  # 上次修改用户名时间
+    created_at = db.Column(db.DateTime, default=datetime.utcnow)
+
+    # 关系
+    exams_created = db.relationship('Exam', back_populates='creator', lazy=True)
+    submissions = db.relationship('Submission', back_populates='user', lazy=True)
+    drafts = db.relationship('Draft', back_populates='user', lazy=True)
+    posts = db.relationship('Post', back_populates='author', lazy=True)
+    replies = db.relationship('Reply', back_populates='author', lazy=True)
+    reactions = db.relationship('Reaction', back_populates='user', lazy=True)
+    bookmarks = db.relationship('Bookmark', back_populates='user', lazy=True)
+    reports = db.relationship('Report', backref='reporter', lazy=True)
+    notifications = db.relationship('Notification', backref='user', lazy=True)
+    contest_memberships = db.relationship('ContestMembership', back_populates='user', lazy=True)
+    contest_registrations = db.relationship('ContestRegistration', backref='user', lazy=True)
+    # teacher_applications 将通过 TeacherApplication 的 back_populates 自动创建
+
+# 杯赛成员表（记录用户在特定杯赛中的角色）
+class ContestMembership(db.Model):
+    id = db.Column(db.Integer, primary_key=True)
+    user_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)
+    contest_id = db.Column(db.Integer, db.ForeignKey('contest.id'), nullable=False)
+    role = db.Column(db.String(20), nullable=False)  # 'owner' 或 'teacher'
+    joined_at = db.Column(db.DateTime, default=datetime.utcnow)
+
+    user = db.relationship('User', back_populates='contest_memberships')
+    contest = db.relationship('Contest', back_populates='members')
+
+    __table_args__ = (db.UniqueConstraint('user_id', 'contest_id', name='uq_user_contest'),)
+
+# 杯赛申请表（用于用户申请举办新杯赛）
+class ContestApplication(db.Model):
+    id = db.Column(db.Integer, primary_key=True)
+    user_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)
+    name = db.Column(db.String(100), nullable=False)
+    organizer = db.Column(db.String(100))
+    description = db.Column(db.Text)
+    contact = db.Column(db.String(100))
+    status = db.Column(db.String(20), default='pending')  # pending, approved, rejected
+    applied_at = db.Column(db.DateTime, default=datetime.utcnow)
+    reviewed_at = db.Column(db.DateTime)
+    total_score = db.Column(db.Integer, default=150)  # 杯赛默认满分
+    start_date = db.Column(db.String(20))  # 申请时填写的开始日期
+    end_date = db.Column(db.String(20))    # 申请时填写的结束日期
+    # 报备信息
+    responsible_person = db.Column(db.String(80))   # 责任人姓名
+    responsible_phone = db.Column(db.String(20))    # 责任人电话
+    responsible_email = db.Column(db.String(120))   # 责任人邮箱
+    organization = db.Column(db.String(100))        # 所属机构/学校
+
+    user = db.relationship('User', backref='contest_applications')
+
+# 杯赛报名表（用户报名参加杯赛）
+class ContestRegistration(db.Model):
+    id = db.Column(db.Integer, primary_key=True)
+    user_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)
+    contest_id = db.Column(db.Integer, db.ForeignKey('contest.id'), nullable=False)
+    registered_at = db.Column(db.DateTime, default=datetime.utcnow)
+
+    __table_args__ = (db.UniqueConstraint('user_id', 'contest_id', name='uq_user_contest_reg'),)
+
+# 杯赛表
+class Contest(db.Model):
+    id = db.Column(db.Integer, primary_key=True)
+    name = db.Column(db.String(100), nullable=False)
+    organizer = db.Column(db.String(100))
+    description = db.Column(db.Text)
+    start_date = db.Column(db.String(20))
+    end_date = db.Column(db.String(20))
+    status = db.Column(db.String(20), default='upcoming')
+    participants = db.Column(db.Integer, default=0)
+    created_by = db.Column(db.Integer, db.ForeignKey('user.id'))
+    created_at = db.Column(db.DateTime, default=datetime.utcnow)
+    past_papers = db.Column(db.Text)  # JSON 存储历年真题 [{year, title, file}]
+    total_score = db.Column(db.Integer, default=150)  # 杯赛默认考试满分
+    visible = db.Column(db.Boolean, default=True)  # 是否对普通用户可见
+    # 报备信息
+    responsible_person = db.Column(db.String(80))   # 责任人姓名
+    responsible_phone = db.Column(db.String(20))    # 责任人电话
+    responsible_email = db.Column(db.String(120))   # 责任人邮箱
+    organization = db.Column(db.String(100))        # 所属机构/学校
+
+    creator = db.relationship('User', backref='contests_created')
+    members = db.relationship('ContestMembership', back_populates='contest', lazy=True, cascade='all, delete-orphan')
+    exams = db.relationship('Exam', backref='contest', lazy=True)
+    posts = db.relationship('Post', back_populates='contest', lazy=True, cascade='all, delete-orphan')
+    teacher_applications = db.relationship('TeacherApplication', back_populates='contest', lazy=True, cascade='all, delete-orphan')
+
+    def get_past_papers(self):
+        return json.loads(self.past_papers) if self.past_papers else []
+
+    def set_past_papers(self, papers):
+        self.past_papers = json.dumps(papers)
+
+# 题库表（杯赛老师和负责人往题库添加题目，负责人选题组卷）
+class QuestionBankItem(db.Model):
+    id = db.Column(db.Integer, primary_key=True)
+    contest_id = db.Column(db.Integer, db.ForeignKey('contest.id'), nullable=False)
+    contributor_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)
+    type = db.Column(db.String(20), nullable=False)  # 'choice', 'fill', 'essay'
+    content = db.Column(db.Text, nullable=False)      # 题目内容
+    options = db.Column(db.Text)                       # JSON，选择题选项
+    answer = db.Column(db.Text)                        # 答案
+    score = db.Column(db.Integer, default=10)          # 建议分值
+    created_at = db.Column(db.DateTime, default=datetime.utcnow)
+
+    contest = db.relationship('Contest', backref='question_bank_items')
+    contributor = db.relationship('User', backref='contributed_questions')
+
+# 考试表
+class Exam(db.Model):
+    id = db.Column(db.Integer, primary_key=True)
+    contest_id = db.Column(db.Integer, db.ForeignKey('contest.id'), nullable=True)
+    title = db.Column(db.String(200), nullable=False)
+    subject = db.Column(db.String(50))
+    duration = db.Column(db.Integer)
+    total_score = db.Column(db.Integer)
+    creator_id = db.Column(db.Integer, db.ForeignKey('user.id'))
+    questions = db.Column(db.Text)  # JSON
+    encrypted_questions = db.Column(db.Text)  # 加密后的试卷内容
+    is_encrypted = db.Column(db.Boolean, default=False)  # 是否加密
+    access_password = db.Column(db.String(128))  # 考试访问密码
+    scheduled_start = db.Column(db.DateTime, nullable=True)  # 预定开始时间
+    scheduled_end = db.Column(db.DateTime, nullable=True)    # 预定结束时间
+    score_release_time = db.Column(db.DateTime, nullable=True)  # 成绩公布时间
+    created_at = db.Column(db.DateTime, default=datetime.utcnow)
+    status = db.Column(db.String(20), default='available')
+
+    creator = db.relationship('User', back_populates='exams_created')
+    submissions = db.relationship('Submission', back_populates='exam', lazy=True, cascade='all, delete-orphan')
+    drafts = db.relationship('Draft', back_populates='exam', lazy=True, cascade='all, delete-orphan')
+
+    def get_questions(self):
+        return json.loads(self.questions) if self.questions else []
+
+    def set_questions(self, questions):
+        self.questions = json.dumps(questions)
+
+# 提交记录表
+class Submission(db.Model):
+    id = db.Column(db.Integer, primary_key=True)
+    exam_id = db.Column(db.Integer, db.ForeignKey('exam.id'))
+    user_id = db.Column(db.Integer, db.ForeignKey('user.id'))
+    answers = db.Column(db.Text)  # JSON
+    score = db.Column(db.Integer, default=0)
+    question_scores = db.Column(db.Text)  # JSON
+    graded = db.Column(db.Boolean, default=False)
+    graded_by = db.Column(db.String(80))
+    submitted_at = db.Column(db.DateTime, default=datetime.utcnow)
+
+    exam = db.relationship('Exam', back_populates='submissions')
+    user = db.relationship('User', back_populates='submissions')
+
+    def get_answers(self):
+        return json.loads(self.answers) if self.answers else {}
+
+    def set_answers(self, answers):
+        self.answers = json.dumps(answers)
+
+    def get_question_scores(self):
+        return json.loads(self.question_scores) if self.question_scores else {}
+
+    def set_question_scores(self, scores):
+        self.question_scores = json.dumps(scores)
+
+# 草稿表
+class Draft(db.Model):
+    id = db.Column(db.Integer, primary_key=True)
+    exam_id = db.Column(db.Integer, db.ForeignKey('exam.id'))
+    user_id = db.Column(db.Integer, db.ForeignKey('user.id'))
+    answers = db.Column(db.Text)  # JSON
+    saved_at = db.Column(db.DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
+
+    exam = db.relationship('Exam', back_populates='drafts')
+    user = db.relationship('User', back_populates='drafts')
+
+    def get_answers(self):
+        return json.loads(self.answers) if self.answers else {}
+
+    def set_answers(self, answers):
+        self.answers = json.dumps(answers)
+
+# 论坛帖子表
+class Post(db.Model):
+    id = db.Column(db.Integer, primary_key=True)
+    title = db.Column(db.String(200), nullable=False)
+    content = db.Column(db.Text, nullable=False)
+    author_id = db.Column(db.Integer, db.ForeignKey('user.id'))
+    tag = db.Column(db.String(50), default='全部')
+    is_official = db.Column(db.Boolean, default=False)
+    pinned = db.Column(db.Boolean, default=False)
+    likes = db.Column(db.Integer, default=0)
+    replies_count = db.Column(db.Integer, default=0)
+    views = db.Column(db.Integer, default=0)
+    has_poll = db.Column(db.Boolean, default=False)
+    images = db.Column(db.Text)  # JSON
+    contest_id = db.Column(db.Integer, db.ForeignKey('contest.id'), nullable=True)
+    created_at = db.Column(db.DateTime, default=datetime.utcnow)
+    updated_at = db.Column(db.DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
+
+    author = db.relationship('User', back_populates='posts')
+    replies = db.relationship('Reply', back_populates='post', lazy=True, cascade='all, delete-orphan')
+    poll = db.relationship('Poll', back_populates='post', uselist=False, cascade='all, delete-orphan')
+    reactions = db.relationship('Reaction', back_populates='post', lazy=True, cascade='all, delete-orphan')
+    bookmarks = db.relationship('Bookmark', back_populates='post', lazy=True, cascade='all, delete-orphan')
+    contest = db.relationship('Contest', back_populates='posts')
+
+    def get_images(self):
+        return json.loads(self.images) if self.images else []
+
+    def set_images(self, images):
+        self.images = json.dumps(images)
+
+# 回复表
+class Reply(db.Model):
+    id = db.Column(db.Integer, primary_key=True)
+    post_id = db.Column(db.Integer, db.ForeignKey('post.id'))
+    author_id = db.Column(db.Integer, db.ForeignKey('user.id'))
+    content = db.Column(db.Text, nullable=False)
+    likes = db.Column(db.Integer, default=0)
+    reply_to = db.Column(db.String(80))
+    created_at = db.Column(db.DateTime, default=datetime.utcnow)
+    updated_at = db.Column(db.DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
+
+    post = db.relationship('Post', back_populates='replies')
+    author = db.relationship('User', back_populates='replies')
+    reactions = db.relationship('Reaction', back_populates='reply', lazy=True, cascade='all, delete-orphan')
+
+# 投票表
+class Poll(db.Model):
+    id = db.Column(db.Integer, primary_key=True)
+    post_id = db.Column(db.Integer, db.ForeignKey('post.id'))
+    question = db.Column(db.String(200), nullable=False)
+    options = db.Column(db.Text)  # JSON
+    voters = db.Column(db.Text)   # JSON
+    multi = db.Column(db.Boolean, default=False)
+    total_votes = db.Column(db.Integer, default=0)
+    created_at = db.Column(db.DateTime, default=datetime.utcnow)
+
+    post = db.relationship('Post', back_populates='poll')
+
+    def get_options(self):
+        return json.loads(self.options) if self.options else []
+
+    def set_options(self, options):
+        self.options = json.dumps(options)
+
+    def get_voters(self):
+        return json.loads(self.voters) if self.voters else {}
+
+    def set_voters(self, voters):
+        self.voters = json.dumps(voters)
+
+# 表情反应表
+class Reaction(db.Model):
+    id = db.Column(db.Integer, primary_key=True)
+    user_id = db.Column(db.Integer, db.ForeignKey('user.id'))
+    post_id = db.Column(db.Integer, db.ForeignKey('post.id'), nullable=True)
+    reply_id = db.Column(db.Integer, db.ForeignKey('reply.id'), nullable=True)
+    reaction = db.Column(db.String(20))
+    created_at = db.Column(db.DateTime, default=datetime.utcnow)
+
+    user = db.relationship('User', back_populates='reactions')
+    post = db.relationship('Post', back_populates='reactions')
+    reply = db.relationship('Reply', back_populates='reactions')
+
+    __table_args__ = (
+        db.UniqueConstraint('user_id', 'post_id', name='uq_user_post_reaction'),
+        db.UniqueConstraint('user_id', 'reply_id', name='uq_user_reply_reaction'),
+    )
+
+# 收藏表
+class Bookmark(db.Model):
+    id = db.Column(db.Integer, primary_key=True)
+    user_id = db.Column(db.Integer, db.ForeignKey('user.id'))
+    post_id = db.Column(db.Integer, db.ForeignKey('post.id'))
+    created_at = db.Column(db.DateTime, default=datetime.utcnow)
+
+    user = db.relationship('User', back_populates='bookmarks')
+    post = db.relationship('Post', back_populates='bookmarks')
+
+    __table_args__ = (db.UniqueConstraint('user_id', 'post_id', name='uq_user_post_bookmark'),)
+
+# 举报表
+class Report(db.Model):
+    id = db.Column(db.Integer, primary_key=True)
+    type = db.Column(db.String(20))
+    target_id = db.Column(db.Integer)
+    reporter_id = db.Column(db.Integer, db.ForeignKey('user.id'))
+    reason = db.Column(db.String(100))
+    detail = db.Column(db.Text)
+    status = db.Column(db.String(20), default='pending')
+    created_at = db.Column(db.DateTime, default=datetime.utcnow)
+
+    # reporter 已在 User 中通过 backref 定义
+
+# 通知表
+class Notification(db.Model):
+    id = db.Column(db.Integer, primary_key=True)
+    user_id = db.Column(db.Integer, db.ForeignKey('user.id'))
+    type = db.Column(db.String(50))
+    content = db.Column(db.Text)
+    from_user = db.Column(db.String(80))
+    post_id = db.Column(db.Integer, nullable=True)
+    read = db.Column(db.Boolean, default=False)
+    created_at = db.Column(db.DateTime, default=datetime.utcnow)
+
+    # user 已在 User 中通过 backref 定义
+
+# 系统公告表（管理员发布的全站通知）
+class SystemNotification(db.Model):
+    id = db.Column(db.Integer, primary_key=True)
+    title = db.Column(db.String(200), nullable=False)
+    content = db.Column(db.Text, nullable=False)
+    author_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)
+    pinned = db.Column(db.Boolean, default=False)
+    created_at = db.Column(db.DateTime, default=datetime.utcnow)
+    updated_at = db.Column(db.DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
+
+    author = db.relationship('User', backref='system_notifications')
+
+# 编辑历史表（可选）
+class EditHistory(db.Model):
+    id = db.Column(db.Integer, primary_key=True)
+    post_id = db.Column(db.Integer, db.ForeignKey('post.id'))
+    title = db.Column(db.String(200))
+    content = db.Column(db.Text)
+    edited_by = db.Column(db.String(80))
+    edited_at = db.Column(db.DateTime, default=datetime.utcnow)
+
+    post = db.relationship('Post')
+
+# 教师申请表（针对特定杯赛）
+class TeacherApplication(db.Model):
+    """教师申请记录（针对特定杯赛）"""
+    id = db.Column(db.Integer, primary_key=True)
+    user_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)
+    contest_id = db.Column(db.Integer, db.ForeignKey('contest.id'), nullable=False)
+    name = db.Column(db.String(80), nullable=False)          # 申请人姓名
+    email = db.Column(db.String(120), nullable=False)       # 申请人邮箱
+    reason = db.Column(db.Text, nullable=False)             # 申请理由
+    status = db.Column(db.String(20), default='pending')    # pending, approved, rejected
+    applied_at = db.Column(db.DateTime, default=datetime.utcnow)
+    reviewed_at = db.Column(db.DateTime)
+    reviewed_by = db.Column(db.Integer, db.ForeignKey('user.id'))
+
+    # 关系
+    user = db.relationship('User', foreign_keys=[user_id], backref='teacher_applications')
+    contest = db.relationship('Contest', back_populates='teacher_applications')
+    reviewer = db.relationship('User', foreign_keys=[reviewed_by])
+
+    __table_args__ = (db.UniqueConstraint('user_id', 'contest_id', name='uq_user_contest_application'),)
+
+# 好友表
+class Friend(db.Model):
+    id = db.Column(db.Integer, primary_key=True)
+    user_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)
+    friend_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)
+    status = db.Column(db.String(20), default='pending')  # pending, accepted
+    created_at = db.Column(db.DateTime, default=datetime.utcnow)
+
+    user = db.relationship('User', foreign_keys=[user_id], backref=db.backref('friends_initiated', lazy='dynamic'))
+    friend = db.relationship('User', foreign_keys=[friend_id], backref=db.backref('friends_received', lazy='dynamic'))
+
+# 试卷收藏表
+class ExamBookmark(db.Model):
+    id = db.Column(db.Integer, primary_key=True)
+    user_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)
+    exam_id = db.Column(db.Integer, db.ForeignKey('exam.id'), nullable=False)
+    created_at = db.Column(db.DateTime, default=datetime.utcnow)
+
+    user = db.relationship('User', backref=db.backref('exam_bookmarks', lazy='dynamic', cascade='all, delete-orphan'))
+    exam = db.relationship('Exam', backref=db.backref('bookmarked_by', lazy='dynamic', cascade='all, delete-orphan'))
+
+    __table_args__ = (db.UniqueConstraint('user_id', 'exam_id', name='uq_user_exam_bookmark'),)
+
+# 聊天室表
+class ChatRoom(db.Model):
+    id = db.Column(db.Integer, primary_key=True)
+    type = db.Column(db.String(20), nullable=False)  # 'private' | 'group' | 'contest'
+    name = db.Column(db.String(100), nullable=True)
+    avatar = db.Column(db.String(200), default='')
+    creator_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=True)
+    contest_id = db.Column(db.Integer, db.ForeignKey('contest.id'), unique=True, nullable=True)
+    announcement = db.Column(db.Text, default='')
+    announcement_by = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=True)
+    announcement_at = db.Column(db.DateTime, nullable=True)
+    created_at = db.Column(db.DateTime, default=datetime.utcnow)
+
+    creator = db.relationship('User', foreign_keys=[creator_id], backref='chatrooms_created')
+    announcement_user = db.relationship('User', foreign_keys=[announcement_by])
+    contest = db.relationship('Contest', backref=db.backref('chatroom', uselist=False))
+    members = db.relationship('ChatRoomMember', backref='room', lazy=True, cascade='all, delete-orphan')
+    messages = db.relationship('Message', backref='room', lazy=True, cascade='all, delete-orphan')
+
+# 聊天室成员表
+class ChatRoomMember(db.Model):
+    id = db.Column(db.Integer, primary_key=True)
+    room_id = db.Column(db.Integer, db.ForeignKey('chat_room.id'), nullable=False)
+    user_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)
+    role = db.Column(db.String(20), default='member')  # 'admin' | 'member'
+    nickname = db.Column(db.String(50), default='')
+    muted = db.Column(db.Boolean, default=False)
+    last_read_at = db.Column(db.DateTime, default=datetime.utcnow)
+    joined_at = db.Column(db.DateTime, default=datetime.utcnow)
+
+    user = db.relationship('User', backref='chat_memberships')
+
+    __table_args__ = (db.UniqueConstraint('room_id', 'user_id', name='uq_room_user'),)
+
+# 消息表
+class Message(db.Model):
+    id = db.Column(db.Integer, primary_key=True)
+    room_id = db.Column(db.Integer, db.ForeignKey('chat_room.id'), nullable=False)
+    sender_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)
+    type = db.Column(db.String(20), default='text')  # 'text' | 'image' | 'file' | 'system' | 'voice'
+    content = db.Column(db.Text, default='')
+    file_url = db.Column(db.String(300), nullable=True)
+    file_name = db.Column(db.String(200), nullable=True)
+    recalled = db.Column(db.Boolean, default=False)
+    reply_to_id = db.Column(db.Integer, db.ForeignKey('message.id'), nullable=True)
+    mentions = db.Column(db.Text, default='')  # JSON array of user IDs, e.g. "[1,2,3]" or "all"
+    created_at = db.Column(db.DateTime, default=datetime.utcnow)
+
+    sender = db.relationship('User', backref='messages_sent')
+    reply_to = db.relationship('Message', remote_side='Message.id', backref='replies')
+    reactions = db.relationship('MessageReaction', backref='message', lazy=True, cascade='all, delete-orphan')
+
+# 消息表情回应表
+class MessageReaction(db.Model):
+    id = db.Column(db.Integer, primary_key=True)
+    message_id = db.Column(db.Integer, db.ForeignKey('message.id'), nullable=False)
+    user_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)
+    emoji = db.Column(db.String(10), nullable=False)
+    created_at = db.Column(db.DateTime, default=datetime.utcnow)
+
+    user = db.relationship('User', backref='message_reactions')
+
+    __table_args__ = (db.UniqueConstraint('message_id', 'user_id', 'emoji', name='uq_msg_user_emoji'),)
+
+# 邀请码表（教师申请审批通过后生成，老师输入邀请码激活身份）
+class InviteCode(db.Model):
+    id = db.Column(db.Integer, primary_key=True)
+    code = db.Column(db.String(32), unique=True, nullable=False)
+    user_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)
+    application_id = db.Column(db.Integer, db.ForeignKey('teacher_application.id'), nullable=False)
+    used = db.Column(db.Boolean, default=False)
+    created_at = db.Column(db.DateTime, default=datetime.utcnow)
+    used_at = db.Column(db.DateTime, nullable=True)
+
+    user = db.relationship('User', backref='invite_codes')
+    application = db.relationship('TeacherApplication', backref='invite_code')