adding lab-18: sqlalchemy

lab-18/forms.py

+from flask_wtf import FlaskForm
+from wtforms import StringField
+from wtforms import HiddenField
+from wtforms import PasswordField
+from wtforms import SubmitField
+from wtforms import validators
+
+class addTwitForm(FlaskForm):
+    twit = StringField('twit', validators = [validators.DataRequired()])
+    submit = SubmitField('submit', [validators.DataRequired()])
+
+class editTwitForm(FlaskForm):
+    twit = StringField('twit', validators = [validators.DataRequired()])
+    twit_id = HiddenField('twit_id')
+    submit = SubmitField('submit', [validators.DataRequired()])
+
+class loginForm(FlaskForm):
+    username = StringField('username', validators = [validators.DataRequired()])
+    password = PasswordField('password', validators =[validators.DataRequired()])
+    password2 = PasswordField('password2', validators=[validators.DataRequired(),
+        validators.EqualTo('password', message='Passwords must match')])
+    submit = SubmitField('submit', [validators.DataRequired()])
+
+

lab-18/models.py

+from flask_sqlalchemy import SQLAlchemy
+import datetime
+
+# we are using the second of flask-sqlalchemy's configuration options
+# which is to create the sqlalchemy object here and bind it to the app once the
+# app is initialised
+# for more on this see http://flask-sqlalchemy.pocoo.org/2.3/api/#configuration
+db = SQLAlchemy()
+
+# the description of our data models follows those in the flask-sqlalchemy
+# quickstart
+# http://flask-sqlalchemy.pocoo.org/2.3/quickstart/
+# for more detail see the doc section on declaring models
+# http://flask-sqlalchemy.pocoo.org/2.3/models/
+class Users(db.Model):
+    user_id = db.Column(db.Integer, primary_key = True)
+    username = db.Column(db.String(50))
+    hashed = db.Column(db.String(150))
+    salt = db.Column(db.String(150))
+    twits = db.relationship('Twits',backref='user', lazy=True)
+
+    # these are the user model attributes required by Flask-Login
+    # see
+    # https://flask-login.readthedocs.io/en/latest/#configuring-your-application
+    def get_id(self):
+        return self.user_id
+
+    def is_authenticated(self):
+        return True
+
+    def is_active(self):
+        return True
+
+    def is_anonymous(self):
+        return False
+
+class Twits(db.Model):
+
+   twit_id = db.Column(db.Integer, primary_key = True)
+   twit = db.Column(db.String(140))
+   user_id = db.Column(db.Integer, db.ForeignKey('users.user_id'))
+   created_at = db.Column(db.DateTime, default=datetime.datetime.now)
+
+   def __repr__(self):
+        return self.twit
+

lab-18/mytwits_mysql.py

+from flask import Flask, request
+from flask import render_template
+from flask import redirect, url_for
+from flask import session, flash, abort
+from vs_url_for import vs_url_for
+from forms import addTwitForm, editTwitForm, loginForm
+from flask_login import LoginManager, login_required
+from flask_login import login_user, logout_user
+# importing current_user from flask-login
+# so that we can access the user object of the currently logged in user
+# at any point (including in templates)
+from flask_login import current_user
+## import the sqlalchemy database and the users & twits db classes
+from models import db,Users,Twits
+## import the passwordhelper class to do password hashing / checking
+from passwordhelper import PasswordHelper
+
+login_manager = LoginManager()
+
+app = Flask(__name__)
+# configure the sqlalchenmy database URI that is used for the connection
+# see http://flask-sqlalchemy.pocoo.org/2.3/config/
+app.config['SQLALCHEMY_DATABASE_URI'] = 'mysql+pymysql://mytwits_user:mytwits_password@localhost/mytwits'
+app.config['SQLALCHEMY_ECHO'] = False
+# initialise the sqlalchemy database connection
+db.init_app(app)
+# initialise flask-login
+login_manager.init_app(app)
+
+app.secret_key = 'A0Zr98j/3yX R~XHH!jmN]LWX/,?RT'
+
+# instantiate a password helper object
+ph = PasswordHelper()
+
+#---- the callback function for flask-login
+@login_manager.user_loader
+def load_user(user_id):
+    # we don't use sql any longer to get the user id; we access it through the
+    # User object provided by sqlalchemy
+    return Users.query.get(int(user_id))
+
+@app.route('/')
+def index():
+    # we don't use sql any longer to get the twits; we access them through the
+    # Twits object provided by sqlalchemy
+    twits = Twits.query.order_by(Twits.created_at.desc()).all() 
+    return render_template("mytwits_mysql.html", twits=twits)
+
+@app.route('/<username>')
+def timeline(username):
+    # instead of having to think in terms of selecting twits using sql queries
+    # e.g. 
+    # "select twit from twits where user_id = (select user_id from users where username = 'dan1' );"
+    # we can just use the objects provided by sqlalchemy
+    twits = Users.query.filter_by(username=username).first().twits
+    return render_template('timeline.html',twits=twits)
+
+@app.route('/add_twit', methods = ['GET', 'POST'])
+@login_required
+def add_twit():
+    form = addTwitForm()
+    if form.validate_on_submit():
+        twit = form.twit.data
+        user_id = current_user.user_id
+        # SQLAlchemy adds an implicit constructor to all model classes which
+        # accepts keyword arguments for all its columns and relationships.
+        # We can use this to create our new twit
+        new_twit = Twits(twit=twit, user_id=user_id)
+        # As explained in http://flask-sqlalchemy.pocoo.org/2.3/queries/
+        # we need to add the object to the flask-sqlalchemy session
+        # and then commit our changes
+        # for it to be inserted in to the database
+        db.session.add(new_twit)
+        db.session.commit()
+        return redirect(vs_url_for('index'))
+    return render_template('add_twit_mysql.html',form=form)
+
+@app.route('/edit_twit', methods = ['GET', 'POST'])
+@login_required
+def edit_twit():
+    user_id = current_user.user_id
+    form = editTwitForm()
+    if request.args.get('id'):
+        twit_id = request.args.get('id')
+        # again, we don't use sql to get the twit
+        # but instead we use the Twits class 
+        # and the query attribute provided by flask-sqlalchemy
+        # see also
+        # http://flask-sqlalchemy.pocoo.org/2.3/queries/#querying-records
+        twit = Twits.query.filter_by(twit_id = twit_id).first()
+        # note that the query object is over all records
+        # to get the specific twit we use the first() methods
+        # having obtained the twits object we can access the text as 
+        # the attribute twit.twit
+        form.twit.data = twit.twit
+        form.twit_id.data = twit_id
+        return render_template('edit_twit_mysql.html',form=form)
+    if form.validate_on_submit():
+        # get the twit_id back from the form
+        twit_id = form.twit_id.data
+        # load that twit
+        twit = Twits.query.filter_by(twit_id = twit_id).first()
+        # change the twit text to the text submitted in the form
+        twit.twit = form.twit.data
+        # commit the change
+        db.session.commit()
+        # so in summary, the way to update db entries is
+        # 1. retrieve the object you want to change
+        # 2. change the attribute
+        # 3. commit the session
+        # see also
+        # https://stackoverflow.com/questions/6699360/flask-sqlalchemy-update-a-rows-information#6701188
+        return redirect(vs_url_for('index'))
+    return render_template('edit_twit_mysql.html',form=form)
+
+@app.route('/delete_twit', methods = ['GET', 'POST'])
+@login_required
+def delete_twit():
+    if request.args.get('id'):
+        twit_id = request.args.get('id')
+        twit_for_deletion = Twits.query.filter_by(twit_id = twit_id).first()
+        # deleting records is simple
+        # instead of add() use delete()
+        # see http://flask-sqlalchemy.pocoo.org/2.3/queries/#deleting-records
+        db.session.delete(twit_for_deletion)
+        db.session.commit()
+    return redirect(vs_url_for('index'))
+   
+@app.route('/login', methods = ['GET', 'POST'])
+def login():
+    form = loginForm()
+    if form.validate_on_submit():
+		password = form.password.data	
+		username = form.username.data
+		# get the user object via sqlalchemy 
+		user = Users.query.filter_by(username=username).first()
+		# use the password helper to validate the password
+		if ph.validate_password(password,user.salt,user.hashed):
+			login_user(user)
+			flash('successfully logged in as {}'.format(user.username))
+			return redirect(url_for('index'))
+		else:
+			flash('please try again')
+    return render_template('login.html',form=form)
+
+      
+@app.route('/logout')
+def logout():
+    # remove the username from the session if it's there
+    logout_user()
+    return redirect(vs_url_for('index'))
+
+if __name__ == '__main__':
+    app.run(debug=True,host='0.0.0.0',port=8000)

lab-18/passwordhelper.py

+import hashlib
+import os
+import base64
+
+class PasswordHelper:
+    def get_hash(self, plain):
+        return hashlib.sha512(plain).hexdigest()
+
+    def get_salt(self):
+        return base64.b64encode(os.urandom(20))
+
+    def validate_password(self, plain, salt, expected):
+        return self.get_hash((salt+plain).encode('utf-8')) == expected

lab-18/templates/add_twit_mysql.html

+{% extends "base.html" %}
+{% block body %}
+
+<div class="jumbotron">
+
+<div >
+	<form class="form-horizontal" method="post" action="/add_twit">
+    {{ form.csrf_token }}
+    <div class='form-group'>
+        <div class='col-md-6'>
+            {% if form.twit.errors %}
+                <ul class='errors'> 
+                    {% for error in form.twit.errors %}
+                        <li>{{ error }}</li>
+                    {% endfor %}
+                </ul>
+            {% endif %}
+            {{ form.twit(class='form-control',placeholder='twit') }}
+        </div>
+     </div>
+    <div class='form-group'>
+        <div class='col-md-6'>
+            {{ form.submit(class='btn btn-primary btn-block') }}
+        </div>
+    </div>
+    </form>
+</div>
+
+</div>
+
+
+{% endblock %}

lab-18/templates/base.html

+<!DOCTYPE html>
+<head>
+
+<meta charset="utf-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1">
+
+    <link rel="stylesheet"
+    href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.3/css/bootstrap.min.css"
+    integrity="sha384-Zug+QiDoJOrZ5t4lssLdxGhVrurbmBWopoEl+M6BdEfwnCJZtKxi1KgxUyJq13dy"
+    crossorigin="anonymous">
+
+
+</head>
+<body>
+<div class="container">
+
+    <!--- flash messages -->
+    {% for category, message in get_flashed_messages(with_categories=true) %}
+    <div class="alert alert-dismissable alert-warning alert-{{ category }}">
+    <button type="button" class="close" data-dismiss="alert">&times;</button>
+    {{ message }}
+    </div>
+    {% endfor %}
+
+
+    {% if current_user.is_authenticated %}
+    <div class="lead mark">
+	logged in as {{ current_user.username }}     
+    </div>
+    {% endif %}
+
+
+    <!--- the body will come from a template that inherits from this one -->
+    {% block body %}{% endblock %}
+
+</div>
+
+<!-- Optional JavaScript -->
+    <!-- jQuery first, then Popper.js, then Bootstrap JS -->
+    <script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
+    <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js" integrity="sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q" crossorigin="anonymous"></script>
+    <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.3/js/bootstrap.min.js" integrity="sha384-a5N7Y/aK3qNeh15eJKGWxsqtnX/wWdSZSKp+81YjTmS15nvnvxKHuzaWwXHDli+4" crossorigin="anonymous"></script>
+
+
+
+</body>
+</html>

lab-18/templates/edit_twit_mysql.html

+{% extends "base.html" %}
+{% block body %}
+
+<div class="jumbotron">
+
+<div >
+	<form class="form-horizontal" method="post" action="/edit_twit">
+    {{ form.csrf_token }}
+    <div class='form-group'>
+        <div class='col-md-6'>
+            {% if form.twit.errors %}
+                <ul class='errors'> 
+                    {% for error in form.twit.errors %}
+                        <li>{{ error }}</li>
+                    {% endfor %}
+                </ul>
+            {% endif %}
+            {{ form.twit(class='form-control') }}
+        </div>
+     </div>
+	<div>
+		{{ form.twit_id }}
+	</div>
+    <div class='form-group'>
+        <div class='col-md-6'>
+            {{ form.submit(class='btn btn-primary btn-block') }}
+        </div>
+    </div>
+    </form>
+</div>
+
+</div>
+
+
+{% endblock %}

lab-18/templates/login.html

+{% extends "base.html" %}
+{% block body %}
+
+<div class="jumbotron">
+
+        <form class='form-horizontal' method="post">
+
+        {{ form.csrf_token }}
+
+        <div class='form-group'>
+            <div class='col-md-6'>
+                {% if form.username.errors %}
+                    <ul class='errors'> 
+                        {% for error in form.username.errors %}
+                            <li>{{ error }}</li>
+                        {% endfor %}
+                    </ul>
+                {% endif %}
+                {{ form.username(class='form-control',placeholder='username') }}
+            </div>
+        </div>
+        <div class='form-group'>
+            <div class='col-md-6'>
+                {% if form.password.errors %}
+                    <ul class='errors'> 
+                        {% for error in form.password.errors %}
+                            <li>{{ error }}</li>
+                        {% endfor %}
+                    </ul>
+                {% endif %}
+                {{
+                form.password(class='form-control',placeholder='password') }}
+            </div>
+        </div>
+        <div class='form-group'>
+            <div class='col-md-6'>
+                {% if form.password2.errors %}
+                    <ul class='errors'> 
+                        {% for error in form.password2.errors %}
+                            <li>{{ error }}</li>
+                        {% endfor %}
+                    </ul>
+                {% endif %}
+                {{ form.password2(class='form-control',placeholder='confirm password') }}
+            </div>
+        </div>
+        <div class='form-group'>
+            <div class='col-md-6'>
+                {{ form.submit(class='btn btn-primary btn-block') }}
+            </div>
+        </div>
+        </form>
+
+</div >
+
+
+{% endblock %}

lab-18/templates/mytwits_mysql.html

+{% extends "base.html" %}
+{% block body %}
+
+<div class="jumbotron">
+{% for twit in twits %}
+ <div class="row">
+  <div class="col-md-4">{{ twit.user.username }}</div>
+  <div class="col-md-4">{{ twit.twit }}</div>
+  <div class="col-md-4"><a href='/edit_twit?id={{ twit.twit_id }}'> edit </a><a
+  href='/delete_twit?id={{ twit.twit_id }}'> delete </a></div>
+ </div>
+ <div class="row">&nbsp;</div> 
+{% endfor %}
+</div>
+
+{% endblock %}

lab-18/templates/timeline.html

+{% extends "base.html" %}
+{% block body %}
+
+<div class="jumbotron">
+{% for twit in twits %}
+ <div class="row">
+  <div class="col-md-4">{{ twit.user.username }}</div>
+  <div class="col-md-4">{{ twit.twit }}</div>
+  <div class="col-md-4"><a href='/edit_twit?id={{ twit.twit_id }}'> edit </a><a
+  href='/delete_twit?id={{ twit.twit_id }}'> delete </a></div>
+ </div>
+ <div class="row">&nbsp;</div> 
+{% endfor %}
+</div>
+
+{% endblock %}

lab-18/user.py

+class User:
+
+    def __init__(self, user_id,username):
+        self.user_id = user_id
+        self.username = username
+
+    @property
+    def username(self):
+        return self.username
+
+    @property
+    def is_authenticated(self):
+        return True
+
+    @property
+    def is_active(self):
+        return True
+
+    @property
+    def is_anonymous(self):
+        return False
+
+    def get_id(self):
+       return self.user_id 
+
+    def __repr__(self):
+        return 'user_id {}'.format(self.user_id) 
+
+            

lab-18/vs_url_for.py

+from flask import url_for
+
+#URL_PREFIX = '/usr/253'
+URL_PREFIX = ''
+
+def vs_url_for(view):
+    url = url_for(view)
+    url = URL_PREFIX + url
+    return url
+
+