How do i delete a post in flask-CodePudding

I can't able to delete a individual post in flask here is my code.i am learning and i can't understand this error.Because i queried the individual post by id then i deleted it then i also did db.commit but still i getting this error don't know why please help me fix this

@app.route('/delete/<int:id>',methods=['GET','POST'])
def delete(id):
    if request.method == 'GET':
        p=Blog.query.filter_by(id=id)
        db.session.delete(p)
        db.session.commit()
    return redirect(url_for('home'))

This is my Template code

{% extends "base.html" %} 
{% block content %} 

<body >
    <div >
        {% for blog in blog %} 
        <a  href="#">Edit</a>
        <a href="{{url_for('delete',id=blog.id)}}">Delete</a>
        <h1>{{blog.title}}</h1>{{blog.posted_on}}
        <p>{{blog.post}}</p>
        {% endfor %}
    </div>
    </body>
{% endblock content %}

This is the error

UnmappedInstanceError
sqlalchemy.orm.exc.UnmappedInstanceError: Class 'flask_sqlalchemy.BaseQuery' is not mapped

Traceback (most recent call last)
File "/home/chirag/Desktop/develop/flaskprojects/myenv/lib/python3.8/site-packages/sqlalchemy/orm/session.py", line 2641, in delete
state = attributes.instance_state(instance)
The above exception was the direct cause of the following exception:
File "/home/chirag/Desktop/develop/flaskprojects/myenv/lib/python3.8/site-packages/flask/app.py", line 2095, in __call__
return self.wsgi_app(environ, start_response)
File "/home/chirag/Desktop/develop/flaskprojects/myenv/lib/python3.8/site-packages/flask/app.py", line 2080, in wsgi_app
response = self.handle_exception(e)
File "/home/chirag/Desktop/develop/flaskprojects/myenv/lib/python3.8/site-packages/flask/app.py", line 2077, in wsgi_app
response = self.full_dispatch_request()
File "/home/chirag/Desktop/develop/flaskprojects/myenv/lib/python3.8/site-packages/flask/app.py", line 1525, in full_dispatch_request
rv = self.handle_user_exception(e)
File "/home/chirag/Desktop/develop/flaskprojects/myenv/lib/python3.8/site-packages/flask/app.py", line 1523, in full_dispatch_request
rv = self.dispatch_request()
File "/home/chirag/Desktop/develop/flaskprojects/myenv/lib/python3.8/site-packages/flask/app.py", line 1509, in dispatch_request
return self.ensure_sync(self.view_functions[rule.endpoint])(**req.view_args)
File "/home/chirag/Desktop/develop/flaskprojects/app.py", line 85, in delete
db.session.delete(p)
File "<string>", line 2, in delete
File "/home/chirag/Desktop/develop/flaskprojects/myenv/lib/python3.8/site-packages/sqlalchemy/orm/session.py", line 2643, in delete
util.raise_(
File "/home/chirag/Desktop/develop/flaskprojects/myenv/lib/python3.8/site-packages/sqlalchemy/util/compat.py", line 207, in raise_
raise exception
sqlalchemy.orm.exc.UnmappedInstanceError: Class 'flask_sqlalchemy.BaseQuery' is not mapped
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This is my full app.py code

from email.policy import default
from enum import unique
from flask import Flask, render_template,redirect, request,url_for
from flask_login import UserMixin
from flask_sqlalchemy import SQLAlchemy
from flask_wtf import FlaskForm
from sqlalchemy import null
from wtforms import TextAreaField,SubmitField,StringField
from wtforms.validators import DataRequired
import os
from datetime import datetime
from flask_migrate import Migrate

app=Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI']='sqlite:///test.db'
app.config['SQLALCHEMY_TRACK_MODIFICATIONS']=True
db=SQLAlchemy(app)
migrate=Migrate(app,db)
SECRET_KEY=os.urandom(32)
app.config['SECRET_KEY']=SECRET_KEY


#database modules


class Blog(db.Model):
    id=db.Column(db.Integer,primary_key=True)
    title=db.Column(db.String(30))
    post=db.Column(db.String(300))
    posted_on=db.Column(db.DateTime,default=datetime.utcnow)

#end of database modules

#Forms

class BlogForm(FlaskForm):
    title=StringField("title",validators=[DataRequired()])
    post=TextAreaField("Enter Your Post here",validators=[DataRequired()])
    submit=SubmitField("POST")

#end of form


#views

@app.route('/')
def home():
    title="Home"
    blog=Blog.query.all()
    kwargs={'title':title,
            'blog':blog}
    return render_template("home.html",**kwargs)


@app.route('/blog/',methods=['GET','POST'])
def create_blog():
    form=BlogForm()
    if form.validate_on_submit():
        new_post=Blog(title=form.title.data,post=form.post.data)
        db.session.add(new_post)
        db.session.commit()
        return redirect(url_for('home'))
    return render_template("blog.html",form=form)

@app.route('/blog<int:id>/')
def single_blog(id):
    blog=Blog.query.filter_by(id=id)
    title="Post"
    kwargs={'blog':blog,'title':title}
    return render_template("single_blog.html",**kwargs)

@app.route('/delete/<int:id>',methods=['GET','POST'])
def delete(id):
    if request.method == 'GET':
        p=Blog.query.filter_by(id=id)
        db.session.delete(p)
        db.session.commit()
    return redirect(url_for('home'))
   
#end of views

if '__main__'==__name__:
    app.run(debug=True)

CodePudding user response：

You need to get the first item of the query using .first()

p=Blog.query.filter_by(id=id).first()