文件数据库关系，sqlalchemy，flask

Question

Good day, every one!
I'm making a website using flask where teacher can post a homework file and student can comment on the post with a solution file attached. But i'm stuck with establishing the relationship between homework file and solution file. Here is my models file:

from blog import login
from blog import db
from datetime import datetime
from flask_login import UserMixin


@login.user_loader
def load_user(id):
    return User.query.get(int(id))


class User(UserMixin, db.Model):
    id = db.Column(db.Integer, primary_key=True)
    access_level = db.Column(db.Integer)
    username = db.Column(db.String(64), index=True, unique=True)
    password = db.Column(db.String(128))
    fullname = db.Column(db.String(128), index=True)
    email = db.Column(db.String(120), index=True, unique=True)
    phone_number = db.Column(db.String(10), index=True, unique=True)
    homework = db.relationship("HomeWork", backref="author", 
        lazy="dynamic")
    answer = db.relationship("Solution", backref="author", 
        lazy="dynamic")

    def __repr__(self):
        return "<User {}>".format(self.username)

    def check_password(self, password):
        return self.password == password

    def is_teacher(self):
        return self.access_level == 1


class HomeWork(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(32))
    data = db.Column(db.LargeBinary)
    timestamp = db.Column(db.DateTime, index=True, 
        default=datetime.now)
    user_id = db.Column(db.Integer, db.ForeignKey("user.id"))



class Solution(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    timestamp = db.Column(db.DateTime, index=True, 
        default=datetime.now)
    data = db.Column(db.LargeBinary)

I want to save homeworks file into database so student can view and then post solutions for each homework . When someone go to a homework page, it will show the homework file in main post and comments of student include their solution file for the homework
Please help me solve this problem!
Thank you so much!

Answer 1

I assume your problem is to save the homework file into the database so that the students can view it and then post solutions, right? So, if that's the case, you don't directly store a file into the SQL database.

Instead, you upload the file in a particular directory, say, 'homework' (All the files will be uploaded here).

And while uploading, you'll rename the file with a "unique id" (this can be skipped, but it is a good practice. since the names wouldn't always be in an orderly fashion)

Then store the "unique id" in the 'homework' table against its actual name and other metadata like Teacher, etc.

So, whenever a student requests for a homework file, the "unique id" (which also happens to be the filename) against it is found. And then the file with the same "unique id" is returned.

A similar way for your the 'solutions'.

A good link to get you started with file uploading in Flask: Flask File Upload