How to Create Routes with Optional URL Variables in Gorilla Mux?

Optional URL Variables in Routes with Gorilla Mux

Gorilla Mux is a versatile routing package for Go that allows for defining routes with URL variables. However, when it comes to creating routes with optional URL variables, the default syntax might not seem immediately apparent.

Original Route without Optional Variable

Based on the provided code:

r.HandleFunc("/view/{id:[0-9]+}", MakeHandler(ViewHandler))

this route serves pages only if an ID is specified, in the form of localhost:8080/view/1.

Adding an Optional URL Variable

To allow optional variables, simply register a second handler for the route without the variable constraint:

r.HandleFunc("/view", MakeHandler(ViewHandler))

This will enable the route to be accessed both with and without a specified ID, as desired.

Handling Optional Variables in Code

When accessing the request variables in your handler function, it's essential to check for the existence of the optional variable:

vars := mux.Vars(r)
id, ok := vars["id"]
if !ok {
  // Handle the case when the ID is not specified
  return
}
// Handle the case when the ID is specified

By implementing this approach, you can create routes with optional URL variables using Gorilla Mux, enabling you to handle different scenarios and provide a more flexible user experience.

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