text: from flask import (
      Blueprint, flash, g, redirect, render_template, request, url_for
  )
  from werkzeug.exceptions import abort
  
  from flaskr.auth import login_required
  from flaskr.db import get_db
  
  bp = Blueprint('blog', __name__)
  
  @bp.route('/')
  def index():
      db = get_db()
      posts = db.execute(
          'SELECT p.id, title, body, created, author_id, username'
          ' FROM post p JOIN user u ON p.author_id = u.id'
          ' ORDER BY created DESC'
      ).fetchall()
      return render_template('blog/index.html', posts=posts)
  
  @bp.route('/create', methods=('GET', 'POST'))
  @login_required
  def create():
      if request.method == 'POST':
          title = request.form['title']
          body = request.form['body']
          error = None
  
          if not title:
              error = 'Title is required.'
  
          if error is not None:
              flash(error)
          else:
              db = get_db()
              db.execute(
                  'INSERT INTO post (title, body, author_id)'
                  ' VALUES (?, ?, ?)',
                  (title, body, g.user['id'])
              )
              db.commit()
              return redirect(url_for('blog.index'))
  
      return render_template('blog/create.html')
  
  def get_post(id, check_author=True):
      post = get_db().execute(
          'SELECT p.id, title, body, created, author_id, username'
          ' FROM post p JOIN user u ON p.author_id = u.id'
          ' WHERE p.id = ?',
          (id,)
      ).fetchone()
  
      if post is None:
          abort(404, "Post id {0} doesn't exist.".format(id))
  
      if check_author and post['author_id'] != g.user['id']:
          abort(403)
  
      return post
  
  @bp.route('/<int:id>/update', methods=('GET', 'POST'))
  @login_required
  def update(id):
      post = get_post(id)
  
      if request.method == 'POST':
          title = request.form['title']
          body = request.form['body']
          error = None
  
          if not title:
              error = 'Title is required.'
  
          if error is not None:
              flash(error)
          else:
              db = get_db()
              db.execute(
                  'UPDATE post SET title = ?, body = ?'
                  ' WHERE id = ?',
                  (title, body, id)
              )
              db.commit()
              return redirect(url_for('blog.index'))
  
      return render_template('blog/update.html', post=post)
  
  @bp.route('/<int:id>/delete', methods=('POST',))
  @login_required
  def delete(id):
      get_post(id)
      db = get_db()
      db.execute('DELETE FROM post WHERE id = ?', (id,))
      db.commit()
      return redirect(url_for('blog.index'))
  
  