URL Rewrite object

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The URL Rewrite object defines friendly URLs, intended to improve the usability and accessibility of a website. 

It lets you define URLs and the corresponding mapping to objects with their parameters.

Defining friendly URLs lets you separate the interface from the implementation:

  • It helps you to make it SEO friendly
  • The defined URLs are independent of the object names and their modularization in the KB
  • The defined URLs are independent of the chosen generator, a feature that adds flexibility and reduces lock-in to a specific platform (.NET, .NET Core or Java).

The object has several parts: 

  • Rewrite Rules
  • Variables
  • Help
  • Documentation

Rewrite Rules

This is the main part of a URL Rewrite Object, as it lets you define the mappings (also called rewrite rules).

Each mapping consists of a part on the left where the URL (or part of it) is specified, and on the right side, the object and its parameters are referenced. Mappings are separated by a semicolon.

home                                 => Home; 

core/clients                        => Core.WWClient;
core/clients/{&ClientId}/{&Mode}    => Core.Client(&Mode,&ClientId);
core/clients/{&ClientId}            => Core.ViewClient(&ClientId);

The above mappings result in URLs like the following:

  • http://www.example.com/home
  • http://www.example.com/core/clients
  • http://www.example.com/core/clients/1/UPD
  • http://www.example.com/core/client/1


  • You do not need to reference all the parameters
  • Creating a URL Rewrite object changes the behavior of the Link Function. Instead of returning document-relative URLs, it returns server-relative URLs when a URL Rewrite object exists. This can introduce breaking changes in your code; for example, if you concatenate the resulting string with another to create an absolute URL.


To use this feature, some restrictions apply


1) Partial parameter references

Missing parameters will be added to the query string:

core/clients/{&ClientId}    => Core.Client(&Mode,&ClientId);

This results in:

  • http://www.example.com/core/clients/1?Mode=UPD

when the object is called as follows:


2) Object mapping without parameter mapping

You can write

core/client => Core.Client;

even if the object Core.Client has a


In this sample, when the parameter style is positional, the resulting URL would be as follows:

  • http://www.example.com/core/client?UPD,1

when the object is called as follows:



GeneXus automatically deploys all the rules defined in the URL Rewrite objects of the KB when deploying a Deployment Unit object. This implies that there must be no conflict among rules defined in different objects.


When deploying to Tomcat 8 or higher, rewrite rules work automatically; however, when you deploy to another Servlet Server, you may need to make extra configurations. For that, take the rules from the urlrewrite.config file to configure the server.


Generators: .NET, .NET Core, Java

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