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05_templates_and_variables.md

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Goals

  • Render HTML templates
  • Pass variables from URL routes
  • Style pages using Jinja

Getting Started

Open the portfolio project directory that you created last time.

  1. Create a new folder named templates.
mkdir templates

This is where we'll place all of the HTML templates that we'll create later on.

  1. Create a new folder named static with subfolders named css and js.
mkdir static
cd static
mkdir css
mkdir js
cd ..

This is where we'll place all of our CSS and JS files.

Your project directory should now contain the following:

flask-05-project-directory

  1. Create a file named about.html and place it inside the templates folder.
<h1>Welcome to the About page.</h1>
  1. Open app.py and render about.html inside your about function by replacing the return string About with render_template(file_name).
from flask import render_template

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

If you try to access <URL>/about/, the contents of about.html will be displayed.

You may remove your about_location() function since we won't be using it anymore.

  1. Create a file named layout.html and place it inside the templates folder.
<!DOCTYPE html>

<html>
	<head>
		<meta charset="utf-8">
        <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
	</head>

	<body></body>
</html>
  1. Check out the following links and save them inside your static folder:
  1. Inside the head tag of your layout.html, add a title and reference your CSS files.
<title>Your Name</title>
<link href="{{ url_for('static', filename='css/bootstrap.min.css') }}" rel="stylesheet">

The url_for() function is used to get the relative path of a file.

  1. Reference your JS files inside the body tag.
<script src="{{ url_for('static', filename='js/jquery-3.3.1.min.js') }}"></script>
<script src="{{ url_for('static', filename='js/bootstrap.min.js') }}"></script>
  1. Add a navigation bar inside the body tag as well. Make sure that the JS references are located at the bottom most part of the body.
<nav class="navbar navbar-inverse">
	<div class="container-fluid">
		<div class="navbar-header">
			<a class="navbar-brand" href="{{ url_for('home') }}">Your Name</a>
		</div>
		<ul class="nav navbar-nav">
			<li><a href="{{ url_for('about') }}">About</a></li>
			<li><a href="{{ url_for('skills') }}">Skills</a></li>
			<li><a href="{{ url_for('projects') }}">Projects</a></li>
			<li><a href="{{ url_for('contact') }}">Contact</a></li>
		</ul>
	</div>
</nav>

The url_for() function can also be used to get the relative path and URL route of the functions in your app.py. In this case, url_for('about') refers to <URL>/about/.

  1. Add a block named body below the navigation bar.
{% block body %}{% endblock %}

Blocks are used to load dynamic content on a static page.

  1. Go back to your app.py. Add an optional string input username to the skills function and set the default value to None.
@app.route("/skills/", defaults={'username': None})
@app.route("/skills/<string:username>/")
def skills():
	return "Skills"
  1. Allow the skills function to accept the username variable and replace the return string with a rendered skills.html template that accepts the variable username.
@app.route("/skills/", defaults={'username': None})
@app.route("/skills/<string:username>/")
def skills(username):
	return render_template("skills.html", username=username)

A variable can be passed to a template by referencing it as a second parameter of the render_template() function.

You may remove your skills_toeic() function since we won't be using it anymore.

  1. Since we don't have skills.html yet, create it and place it inside the templates folder.
<h1>Welcome to the Skills page.</h1>
  1. To utilize the layout.html that we made earlier, extend it inside your skills.html and put your welcome header inside the body block.
{% extends "layout.html" %}

{% block body %}

<h1>Welcome to the Skills page.</h1>

{% endblock %}

Contents added in between the block tags are loaded with the layout page specified. If you try to access <URL>/skills/, the contents of layout.html and skills.html will be displayed.

  1. To use the variable username inside skills.html, encase the variable name inside double curly braces.
<p>
	Hi, {{username|title}}! 
</p>

Use the title keyword to make the first letter of each word capitalized.

  1. What happens when the value of username is None? Use an if-else statement with Jinja to handle this problem.
<p>
{% if username == None %}
	Hi, stranger. What\'s your name?
{% else %}
	Hi, {{username|title}}! 
{% endif %}
</p>

If you try to access <URL>/skills/ without an input, it will now display the message:

Hi, stranger. What's your name?

  1. Go back to your app.py. Remove the optional integer input amount from the URL routes of projects function and render projects.html instead.
@app.route("/projects/")
def projects():
	return render_template("projects.html")
  1. Inside the projects function, define a list of projects inside the variable projects.
projects = ["Facebook", "Twitter", "Instagram", "Uber", "Grab"]
  1. Import randint() from random and use it to assign a random integer to a variable named randNo.

Add this to the top part of your code:

from random import randint

Add this inside projects function:

randNo = randint(0, len(projects) - 1)

The first parameter of randint() refers to the lowest possible number while the second parameter refers to the highest possible number, which is equal to the number of projects minus 1 since we started counting from 0.

  1. Create a variable named project which contains a random project from the list of projects and pass all the variables to projects.html.
project = projects[randNo]

return render_template("projects.html", **locals())

The **locals keyword is used to pass multiple variables.

  1. Create projects.html inside the static folder with the same structure as skills.html.
{% extends "layout.html" %}

{% block body %}

<h1>Welcome to the Projects page.</h1>

{% endblock %}
  1. Finally, use the variables that we created earlier inside the projects function while utilizing the for loop statement.
<h3> These are what I\'ve done so far:</h3>
<ul>
{% for p in projects %}
	<li>{{ p }}</li>
{% endfor %}
</ul>

<p>... and <b>{{ project }}</b> is the one that I enjoyed coding the most.</p>

This displays a bulleted list of projects and the randomly selected project as follows:

There are what I've done so far:

  • Facebook
  • Twitter
  • Instagram
  • Uber
  • Grab

... and Facebook is the one that I enjoyed coding the most.

Congratulations!

You're halfway through the entire tutorial. Now try to create a template for all of your existing pages and feel free to customize them and their contents!