BOOK REVIEW

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PROJECT SCREENSHOT

login page	sign-up page

sign-success-page	list of books page

give review page	view review page

CREATING FASK SERVER

Create server syntax

from flask import Flask
app = Flask(__name__)

@app.route('/')
def hello_world():
return 'Hello, World!'

Run server command

• on linux export appName.py

$ export FLASK_APP=main.py
$ export FLASK_ENV=development
$ flask run

• on window we need to set environment variable ps is powershell make sure venv is activated

(venv) PS > $env:FLASK_APP = "app.py"
(venv) PS > $env:FLASK_ENV= "development"    # optional
(venv) PS > flask run

DATABASE

postgres vs mysql

• postgres

• PostgreSQL is an object-relational database management system (ORDBMS) based on postgres
• based on object data model
• support sql structure-query-language
• docs: ![what is postgres]
• ORDBMS vs OODBMS -- OODBMS - object oriented database management system -- OODBMS aimed at applications where an object-centric viewpoint is appropriate, mainly used in cpp or java -- ORDBMS focus on large data collections

• mysql

• Mysql is an relational database management system (RDBMS) based on sql
• based on relational data model
• docs: []
• RDBMS vs ORDBMS -- RDBMS stores only data. -- ORDBMS Stores data as well as methods to use it. -- ORDBMS Handles larger and complex data than RDBMS.

• mongodb

• MongoDB is a document oriented database management system
• based on document data model
• use MongoDb query language (mql) does not support sql
• docs: []

postgres sql commong syntax

• heroku used for db based on postgres

• email : dheerajbishnoi123
• db : https://data.heroku.com/datastores/c848db28-1ef7-4d42-b21b-2d8d015bf5a2
• why i use : it provide free db with 10000 entries on heroku cloud
• Host ec2-54-83-17-151.compute-1.amazonaws.com
• Database dce25fb79tcjcv
• User ntcwaduvpgeowm
• Port 5432

object relational mapping

• orm module provide by sqlalchemy python library
• this orm module have 2 method scoped_session(start session), sessionmaker(create connection)

• connect with db syntax

db = scoped_session(sessionmaker(bind=create_engine('postgres://user:secret@host:port/database', echo = True))

• query syntax from backend to database

bookselect = db.execute("SELECT * FROM book WHERE book_id = :book_id",{"book_id": book_id}).fetchone()
sid = db.execute("SELECT student_id FROM student WHERE username =:username", {"username": username}).fetchone();
booksdb = db.execute("SELECT * FROM book LIMIT 10 ").fetchall()
db.execute("SELECT * FROM review WHERE student = :student_id and book =:book_id", {"student_id": student_id, "book_id": book_id}).rowcount
db.execute("INSERT INTO review (scale, texts, student, book) VALUES (:scale, :texts, :student, :book)", {"scale": scale, "texts": texts, "student": student_id, "book": book_id})
db.commit()