Jinja2 Templates

Code

from flask import Flask, render_template

app = Flask(__name__)

@app.route("/greet/<name>")
def greet(name):
    return render_template("greet.html", name=name, items=["a", "b", "c"])

# templates/greet.html
{% extends "base.html" %}
{% block content %}
  <h1>Hello {{ name|capitalize }}</h1>
  <ul>
    {% for item in items %}
      <li>{{ loop.index }}: {{ item }}</li>
    {% endfor %}
  </ul>
{% endblock %}

Explanation

render_template() loads a Jinja2 file from the templates/ folder and injects context variables. Templates support inheritance with extends and block, control flow with for and if, and filters like capitalize. Loop variables such as loop.index provide iteration metadata.

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