Home - News ( United States | United Kingdom | Italy | Germany ) - Football scores

Showing content from https://www.geeksforgeeks.org/python/flask-variable-rule/ below:

Flask - Variable Rule - GeeksforGeeks

Last Updated : 19 Mar, 2025

Flask variable rules allow us to create dynamic URLs by defining variable parts within the route. This makes it possible to capture values from the URL and pass them to view functions.

• A variable rule is defined using <variable-name> within the route.
• The captured variable is automatically passed as a keyword argument to the associated function.
• This feature helps build more flexible and interactive web applications by allowing dynamic content retrieval based on user input.

The following converters are available in Flask-Variable Rules:

• String - It accepts any text without a slash(the default).
• int - accepts only integers. ex =23 
• float - like int but for floating point values ex. = 23.9
• path - like the default but also accepts slashes.
• any - matches one of the items provided.
• UUID = accepts UUID strings.

In this code we will create a basic flask app in which we will return a simple welcome line. Run the app by executing this command in the terminal - "python app.py".

from flask import Flask
app = Flask(__name__)


@app.route('/')
def msg():
    return "Welcome To The GreeksForGreeks"

 # we run code in debug mode
 app.run(debug=True)

Output:

In this code, we will define a function that handles a dynamic string variable in the URL.

from flask import Flask

app = Flask(__name__)

@app.route('/')
def msg():
    return "Welcome"

# We defined string  function
@app.route('/vstring/<name>')
def string(name):
    return "My Name is %s" % name

# we run app debugging mode
app.run(debug=True)

Output :

Explanation:

• @app.route('/'): Defines the homepage route that returns a welcome message.
• @app.route('/vstring/<name>'): A dynamic route that takes a string parameter and displays it in a message.
• app.run(debug=True): Runs the Flask app with debugging enabled.

To understand how integer variables work in flask let's create a function that handles integers since Flask doesn't define it by default. Finally, we return the integer value and run the app. To access the integer page, we include the function name and an integer in the URL.

from flask import Flask

app = Flask(__name__)

@app.route('/')
def msg():
    return "Welcome"

# define int function
@app.route('/vint/<int:age>')
def vint(age):
    return "I am %d years old " % age

# we run our code in debug mode
app.run(debug=True)

Output:

Explanation:vint() function handles URLs with an integer parameter (<int:age>). It ensures only integers are accepted and returns a formatted string with the provided age.

To demonstrate a float variable in Flask, we define a float function since Flask doesn’t define it by default. The function returns the float value, and we run the app using Flask run. To access the float page, we include the function name and a floating-point number in the URL.

from flask import Flask

app = Flask(__name__)

@app.route('/')
def msg():
    return "Welcome"

# define float function
@app.route('/vfloat/<float:balance>')
def vfloat(balance):
    return "My Account Balance %f" % balance

 # we run our code in debugging mode
app.run(debug=True)

Output:

Explanation:vfloat function handles URLs with a float value (e.g., /vfloat/100.50). It returns a formatted message displaying the float value.

RetroSearch is an open source project built by @garambo | Open a GitHub Issue

Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo

HTML: 3.2 | Encoding: UTF-8 | Version: 0.7.4