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Flask (Reference) · Lesson 43 of 56

Jinja Templates

Source: 13-Flask/flask/jinja.py

Start here — no coding background needed

What you will learn

HTML templates with placeholders for dynamic data.

In simple words

Like a letter template: Dear {{name}}, your order is ready.

Build websites with Python — read for overview; run full apps on your computer later.

Easy example — try this first

Easy example — run this first. Change values and press Run again.

Python

Runs in your browser via Pyodide — no server. First run may take a few seconds.

Reference notes (from full bootcamp)

Optional — deeper detail for when you are ready

Reference script from the bootcamp repo. Read the code below; run a simplified version in the playground when marked runnable.

Example HCL
HCL
### Building Url Dynamically
## Variable Rule
### Jinja 2 Template Engine

### Jinja2 Template Engine
'''
{{  }} expressions to print output in html
{%...%} conditions, for loops
{#...#} this is for comments
'''

from flask import Flask,render_template,request,redirect,url_for
'''
 It creates an instance of the Flask class, 
 which will be your WSGI (Web Server Gateway Interface) application.
'''
###WSGI Application
app=Flask(__name__)

@app.route("/")
def welcome():
    return "<html><H1>Welcome to the flask course</H1></html>"

@app.route("/index",methods=['GET'])
def index():
    return render_template('index.html')

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



## Variable Rule
@app.route('/success/<int:score>')
def success(score):
    res=""
    if score>=50:
        res="PASSED"
    else:
        res="FAILED"

    return render_template('result.html',results=res)

## Variable Rule
@app.route('/successres/<int:score>')
def successres(score):
    res=""
    if score>=50:
        res="PASSED"
    else:
        res="FAILED"
    
    exp={'score':score,"res":res}

    return render_template('result1.html',results=exp)

## if confition
@app.route('/sucessif/<int:score>')
def successif(score):

    return render_template('result.html',results=score)

@app.route('/fail/<int:score>')
def fail(score):
    return render_template('result.html',results=score)

@app.route('/submit',methods=['POST','GET'])
def submit():
    total_score=0
    if request.method=='POST':
        science=float(request.form['science'])
        maths=float(request.form['maths'])
        c=float(request.form['c'])
        data_science=float(request.form['datascience'])

        total_score=(science+maths+c+data_science)/4
    else:
        return render_template('getresult.html')
    return redirect(url_for('successres',score=total_score))
            
        




if __name__=="__main__":
    app.run(debug=True)

Browser practice only — full example needs Python on your computer (files, Flask, threads, etc.).

Practice test — try yourself

Write code, press Check. Wrong answer shows the correct code to copy & run.

You learned "Jinja Templates". Use print() to show: Done: Jinja Templates

Hint: Use one print() with the exact text.

Python