So, I'm working on a little blog-style kind of web app as a personal project. I have the bul of it working by now, but I've been having trouble trying to implement comments on the posts.
The way I have my posts set up is through an SQLAlchemy ORM model, which works fine. It has content and title fields and what not, and a many-to-one relationship to the post author, like such:
class Post(db.Model):
id = db.Column(db.Integer, primary_key = True)
title = db.Column(db.String(100), nullable=False)
date_posted = db.Column(db.DateTime, nullable=False, default=datetime.utcnow)
content = db.Column(db.Text, nullable=False)
feature_image = db.Column(db.String, nullable=True)
user_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)
comments = db.relationship('Comment', backref='original_post', lazy=True)
My comments follow the same kind of structure, having a many-to-one relationship to the post, like this:
class Comment(db.Model):
id = db.Column(db.Integer, primary_key = True)
date_posted = db.Column(db.DateTime, nullable=False, default=datetime.utcnow)
content = db.Column(db.Text, nullable=False)
post_id = db.Column(db.Integer, db.ForeignKey('post.id'), nullable=False)
user_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)
So, in order to have the comments show up below the post, I am trying to query the 'comment' table and filter for the 'post_id', which supposedly matches the post.id, from the 'post' table:
@app.route('/post/<int:post_id>')
def post(post_id):
post = Post.query.get_or_404(post_id)
comments = Comment.query.filter(Comment.original_post==post)
But when I try to load the post page, it throws me the following error:
sqlalchemy.exc.OperationalError: (sqlite3.OperationalError) no such column: comment.post_id
[SQL: SELECT comment.id AS comment_id, comment.date_posted AS comment_date_posted, comment.content AS comment_content, comment.post_id AS comment_post_id, comment.user_id AS comment_user_id
FROM comment
WHERE ? = comment.post_id]
[parameters: (1,)]
(Background on this error at: http://sqlalche.me/e/e3q8)
I looked through some other threads on the subject which suggested a.join before the query like this:
comments = Comment.query.join(Post).filter(Post.id == post_id).all()
But I get a similar error:
sqlalchemy.exc.OperationalError: (sqlite3.OperationalError) no such column: comment.post_id
[SQL: SELECT comment.id AS comment_id, comment.date_posted AS comment_date_posted, comment.content AS comment_content, comment.post_id AS comment_post_id, comment.user_id AS comment_user_id
FROM comment JOIN post ON post.id = comment.post_id
WHERE post.id = ?]
[parameters: (1,)]
My 'comment' table in the db file was simply missing the Foreign Key field.
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