Providing Optional Query Parameters in GET Requests with Gorilla Mux

When defining route handlers with Gorilla Mux, it may be necessary to have optional query parameters in GET requests. This enables the flexibility of providing a subset of the expected parameters.

In Gorilla Mux, optional query parameters can be achieved by removing the constraints when defining the route. Instead of using .Queries() method, the route can be defined as follows:

r.HandleFunc("/user", UserByValueHandler).Methods("GET")

Within the handler function UserByValueHandler, the query parameters can be extracted from the request:

func UserByValueHandler(w http.ResponseWriter, r *http.Request) {
    v := r.URL.Query()

    username := v.Get("username")
    email := v.Get("email")
    ... 
}

By removing the constraints using .Queries(), the handler function can then check the presence of the query parameters as needed. This approach allows for more flexible query parameter handling, enabling optional parameters to be included or excluded as desired.