Day 69 - Blog with Users

learning from 100 Days of Code: The Complete Python Pro Bootcamp for 2022

Learning Point

01. create decorator @admin_only
Login Required Decorator
functools.wraps

02. Set Error Pages
Custom Error Pages

03. Build One To Many relationship
Basic Relationship Patterns
relationship.back_populates
relationship.backref

04. Set random Gravatar
Flask-Gravatar

main.py

from flask import Flask, render_template, redirect, url_for, flash, abort
from flask_bootstrap import Bootstrap
from flask_ckeditor import CKEditor
from datetime import date
from werkzeug.security import generate_password_hash, check_password_hash
from flask_sqlalchemy import SQLAlchemy
from sqlalchemy.orm import relationship
from flask_login import UserMixin, login_user, LoginManager, login_required, current_user, logout_user
from forms import CreatePostForm, RegisterForm, LoginForm, CommentForm
from flask_gravatar import Gravatar
from functools import wraps

app = Flask(__name__)
app.config['SECRET_KEY'] = '8BYkEfBA6O6donzWlSihBXox7C0sKR6b'
ckeditor = CKEditor(app)
Bootstrap(app)

##CONNECT TO DB
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///blog.db'
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
db = SQLAlchemy(app)

##CONNECT TO FLASK LOGIN
login_manager = LoginManager()
login_manager.init_app(app)


@login_manager.user_loader
def load_user(user_id):
    # if user not valid, return None
    return User.query.get(user_id)


##CONFIGURE TABLES

class User(db.Model, UserMixin):
    __tablename__ = "users"
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(80), nullable=False)
    email = db.Column(db.String(250), unique=True, nullable=False)
    password = db.Column(db.String(80), nullable=False)
    # posts = relationship("BlogPost", back_populates="author")
    # comments = relationship("Comment", back_populates="comment_author")


class BlogPost(db.Model):
    __tablename__ = "blog_posts"
    id = db.Column(db.Integer, primary_key=True)
    author = relationship("User", backref="blog_posts")
    author_id = db.Column(db.Integer, db.ForeignKey('users.id'))
    title = db.Column(db.String(250), unique=True, nullable=False)
    subtitle = db.Column(db.String(250), nullable=False)
    date = db.Column(db.String(250), nullable=False)
    body = db.Column(db.Text, nullable=False)
    img_url = db.Column(db.String(250), nullable=False)
    # comments = relationship("Comment", back_populates="parent_post")


class Comment(db.Model):
    __tablename__ = "comments"
    id = db.Column(db.Integer, primary_key=True)
    post_id = db.Column(db.Integer, db.ForeignKey('blog_posts.id'))
    author_id = db.Column(db.Integer, db.ForeignKey('users.id'))
    parent_post = relationship("BlogPost", backref="comments")
    author = relationship("User", backref="comments")
    text = db.Column(db.Text, nullable=False)


# db.create_all()


################################################

def admin_only(f):
    '''
    @wrap(add_new_)
    def check_if_admin(*args, **kwargs):
        if current_user.get_id() != '1':
            return "503"
        return add_new_post(*args, **kwargs)

    decorator 功用：
    1. 先整理方程式
    @admin_only(add_new_post) = admin_only(add_new_post) = check_if_admin

    2. 再呼叫啟動
    add_new_post() = check_if_admin()

    3. wrap(f) = wrap(add_new_post)
    If WITH => 最後會回歸 add_new_post => @app.route("/new-post") 會觸發 add_new_post
    If WITHOUT => add_new_post 被 check_if_admin 取代 => @app.route("/new-post") 會觸發 check_if_admin
    '''

    @wraps(f)
    def check_if_admin(*args, **kwargs):
        if current_user.get_id() != '1':
            abort(403)
        return f(*args, **kwargs)

    return check_if_admin


################################################

@app.route('/')
def get_all_posts():
    posts = BlogPost.query.all()
    user_id = current_user.get_id()
    return render_template("index.html", all_posts=posts, user_id=user_id)


@app.route('/register', methods=['GET', 'POST'])
def register():
    form = RegisterForm()
    if form.validate_on_submit():
        if User.query.filter_by(email=form.email.data).first() is not None:
            flash("You've already sign up with that email, log in instead!")
            return redirect(url_for('login'))

        hash_and_salted_psw = generate_password_hash(
            form.password.data,
            method='pbkdf2:sha256',
            salt_length=8
        )
        new_user = User(
            name=form.name.data,
            email=form.email.data,
            password=hash_and_salted_psw
        )
        db.session.add(new_user)
        db.session.commit()
        login_user(new_user)
        return redirect(url_for('get_all_posts'))
    return render_template("register.html", form=form)


@app.route('/login', methods=["GET", "POST"])
def login():
    form = LoginForm()
    if form.validate_on_submit():
        user = User.query.filter_by(email=form.email.data).first()

        if user is None:
            flash("That email does not exist, please try again.")
            return redirect(url_for('login'))

        elif not check_password_hash(user.password, form.password.data):
            flash("Password incorrect, please try again.")
            return redirect(url_for('login'))

        else:
            login_user(user)
            return redirect(url_for('get_all_posts'))

    return render_template("login.html", form=form)


@app.route('/logout')
def logout():
    logout_user()
    return redirect(url_for('get_all_posts'))


@app.route("/post/<int:post_id>", methods=['GET', 'POST'])
def show_post(post_id):
    form = CommentForm()
    user_id = current_user.get_id()
    requested_post = BlogPost.query.get(post_id)

    gravatar = Gravatar(app,
                        size=150,
                        rating='g',
                        default='retro',
                        force_default=False,
                        force_lower=False,
                        use_ssl=False,
                        base_url=None)

    if form.validate_on_submit():
        if not current_user.is_authenticated:
            flash("You need to login or register to comment.")
            return redirect(url_for('login'))
        else:
            new_comment = Comment(
                text=form.comment.data,
                parent_post=BlogPost.query.get(post_id),
                author=current_user
            )
            db.session.add(new_comment)
            db.session.commit()
    return render_template("post.html", post=requested_post, form=form, user_id=user_id, gravatar=gravatar)


@app.route("/about")
def about():
    return render_template("about.html")


@app.route("/contact")
def contact():
    return render_template("contact.html")


@app.route("/new-post", methods=['GET', 'POST'])
@admin_only
def add_new_post():
    form = CreatePostForm()
    if form.validate_on_submit():
        new_post = BlogPost(
            title=form.title.data,
            subtitle=form.subtitle.data,
            body=form.body.data,
            img_url=form.img_url.data,
            author=current_user,
            date=date.today().strftime("%B %d, %Y")
        )
        db.session.add(new_post)
        db.session.commit()
        return redirect(url_for("get_all_posts"))
    return render_template("make-post.html", form=form)


@app.route("/edit-post/<int:post_id>", methods=['GET', 'POST'])
@admin_only
def edit_post(post_id):
    post = BlogPost.query.get(post_id)
    edit_form = CreatePostForm(
        title=post.title,
        subtitle=post.subtitle,
        img_url=post.img_url,
        author=current_user,
        body=post.body
    )
    if edit_form.validate_on_submit():
        post.title = edit_form.title.data
        post.subtitle = edit_form.subtitle.data
        post.img_url = edit_form.img_url.data
        post.body = edit_form.body.data
        db.session.commit()
        return redirect(url_for("show_post", post_id=post.id))

    return render_template("make-post.html", form=edit_form, is_edit=True)


@app.route("/delete/<int:post_id>")
@admin_only
def delete_post(post_id):
    post_to_delete = BlogPost.query.get(post_id)
    db.session.delete(post_to_delete)
    db.session.commit()
    return redirect(url_for('get_all_posts'))


if __name__ == "__main__":
    app.run(host='0.0.0.0', port=5000, debug=True)