provides()

1. Provide HTML, XML, and JSON responses
function config() {
    provides("html,xml,json");
}

2. Provide only JSON and CSV
function config() {
    provides("json,csv");
}

3. Default behavior (HTML only)
function config() {
    provides(); // equivalent to provides("html")
}

4. Handling requested format in the action
function show() {
    // Wheels automatically detects the requested format and renders accordingly
    renderwith(data=model("user").findByKey(params.id));
}