WebServer library help

[w9ran]

I'm trying to use the WebServer library to create a web interface to configure a PicoW-based device. While I'm grateful for the examples provided, I would really appreciate being able to look at other example or documentation on the library functions. I know how to create html pages and serve them from the PicoW, but I'm struggling to understand how to parse and use information from GET or POST requests. Specifically, the examples show calls to a function called "server.on", i.e.:
server.on("/", handleRoot);

I've searched for "server.on" in every file in the WebServer library and cannot find where it is defined. Can anyone help me understand how to use this and other potentially useful library functions? It has to be defined somewhere but I sure haven't been able to find it.

It appears the PicoW library is a subset of a WebServer library developed by Ivan Grokhotkov about 10 years ago for the ESP32, based on similarities noted:
https://github.com/espressif/arduino-esp32/tree/master/libraries/WebServer

I still haven't found an explanation of the server.on function, and since the Pico library looks to be a subset of the ESP32 one, I thought I'd ask for help before going too deeply down that path.

Since my application requires updating variables that are being sent via GET I think it's very basic but will be a good platform for building other web-controlled projects. I've looked at dozens of PicoW projects online but the majority are done with Micropython, and the relatively few done in C++ may not be compatible with the Arduino-Pico Core, which I want to use for other reasons.

Thanks for any examples or suggestions that might be helpful, Bob.

[earlephilhower]

I took the ESP32 WebServer and split out the network processing from the HTTP request handling. That allows me to do HTTP and HTTPS servers with the same code (there's no HTTPS (TLS) server in the ESP32 AIUI). There have been some divergence since I pulled it in a few years ago, but nothing major AFAIK.

The methods are prototyped in the class here

arduino-pico/libraries/WebServer/src/HTTPServer.h

Lines 99 to 101 in 3cb5c31

	RequestHandler& on(const Uri &uri, THandlerFunction fn);
	RequestHandler& on(const Uri &uri, HTTPMethod method, THandlerFunction fn);
	RequestHandler& on(const Uri &uri, HTTPMethod method, THandlerFunction fn, THandlerFunction ufn); //ufn handles file uploads

Server.on lets you get a callback when a request comes in and do something about it. You can set a variable, return a web page or CGI response, light an LED, etc. When a HTTP request comes in from the net the WebServer class parses headers and cookies and then checks for callbacks and calls them if registered. Check the examples here or something more complicated w/POST and other stuff like in https://github.com/earlephilhower/BackgroundAudio/blob/master/examples/WebradioMP3PlusWebUI/WebradioMP3PlusWebUI.ino . The ESP32 examples should also basically work (replace WiFiClient with NetworkClient, of course, since they renamed things in 3.0).