URLs in web2py

Absolute URLs in web2py 🎯

In web2py, by default, URL generates relative URLs. However, we can also generate absolute URLs by specifying the scheme and host arguments. This method is useful, for example, when we are inserting URLs in email messages):

URL(..., scheme='http', host='www.codingninjas.com')

By setting the arguments to True, you may automatically include the current request's scheme and host.

URL(..., scheme=True, host=True)

If necessary, the URL function additionally accepts a port parameter that specifies the server port.

Digitally signed URLs in web2py 🎯

We have the ability to sign a URL when it is generated digitally. A _signature GET variable that the server may validate will be added as a result. There are two methods to go about this.

Method 1

we can pass the following arguments  to the URL function:

hmac_key: the key for signing the URL (It is a string )

salt: an optional string to salt the data before signing

hash_vars: An optional list of GET variables, or names of variables from the URL query string, to be included in the signature. Additionally, it may be adjusted to either True (the default), which includes all variables, or False, which excludes all variables.

Example

KEY = 'anykey'

def one():
    return dict(link=URL('two', vars=dict(d=145), hmac_key=KEY))

def two():
    if not URL.verify(request, hmac_key=KEY): raise HTTP(403)
    # do something
    return locals()

You can also try this code with Online Python Compiler

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A digitally signed URL looks like this:

/application/default/two?d=145&_signature=4981bc70e13866bb60e52a09073560ae822224e9

Note that the URL.verify function is used to validate the digital signature. The URL is verified using the hmac key, salt, and hash vars parameters supplied to the URL function when the digital signature was formed. The values of these arguments must match the values that were passed to the URL function when the digital signature was created.

Method 2

The second method is more sophisticated. This method mainly uses the digitally signed URLs in conjunction with Auth.

Example:

@auth.requires_login()
def one():
    return dict(link=URL('two', vars=dict(a=145), user_signature=True)

@auth.requires_signature()
def two():
    # do something
    return locals()

You can also try this code with Online Python Compiler

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In the above example, the session shares an automatically produced hmac key. As a result, action two can provide action one access control authority. The link is genuine if it has been generated and signed; else, it is invalid. The link will be invalid if it is taken by another user.

Always digitally signing Ajax callbacks is a good idea. You may utilize the user signature parameter from the web2py LOAD function for this if you do so:

{{=LOAD('default', 'two', vars=dict(a=145), ajax=True, user_signature=True)}}

Frequently Asked Question

What do you mean by URL?

A Uniform resource locator is the address of a given unique resource on the Web. Every valid URL points to a specific resource. These resources can be multimedia files or text or pdf files.

How do static files are mapped to URLs in web2py?

When creating URLs for static files for our apps, we should always utilize the URL function. When uploaded using the administrative interface, static files go into the application's static subdirectory, where they are kept.

What is the basic structure of URLs?

The Uniform resource locator follows a general structure i.e. protocol://domain/path.

What is web2py used for?

Web2py allows web developers to use Python to create dynamic online content. Web2py is intended to assist decrease time-consuming web development activities such as creating web forms from scratch, while a web developer may create a form from scratch if necessary.

Which companies are using the web2py framework?

Vidjil, Sarapis, StopStalk, Groupthink, Rune Interactive, Oceangrafix.com, and Food2Fork are a few famous companies using web2py.

Conclusion

In this article, we have extensively discussed URLs in web2py. We discussed building a URL function and what arguments go into that function. We also saw Absolute and Digitally signed URLs in web2py. If you would like to learn more, check out our articles on 

• Web2py
• What is web2py?
• Web2Py Introduction
• Web2py Installation
• Creating a New Web2py application
• Web2py- Prepare the Tool
• Web2py- Troubleshooting Use Cases
• Web2py- Capacity Planning Use Cases
   

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