ESP32 WebServer Library – removeHandler()

/*
 * Author: Avant Maker
 * Date: March 17, 2025
 * Version: 1.0
 * License: MIT 
 * 
 * Description: 
 * This example demonstrates how to use ESP32 WebServer Library's 
 * removeHandler() method to remove a handler from the server. 
 *
 * Code Source:
 * This example code is sourced from the Comprehensive Guide
 * to the ESP32 Arduino Core Library, accessible on AvantMaker.com.
 * For additional code examples and in-depth documentation related to
 * the ESP32 Arduino Core Library, please visit:
 *
 * https://avantmaker.com/home/all-about-esp32-arduino-core-library/
 *
 * AvantMaker.com, your premier destination for all things
 * DIY, AI, IoT, Smart Home, and STEM projects. We are dedicated
 * to empowering makers, learners, and enthusiasts with
 * the resources they need to bring their innovative ideas to life.
 */
 
#include <WiFi.h>
#include <WebServer.h>

// Replace with your network credentials
const char* ssid = "your_SSID";          // Replace with your Wi-Fi SSID
const char* password = "your_PASSWORD";  // Replace with your Wi-Fi password

WebServer server(80);

// Variable to store the handler object we might want to remove
RequestHandler* dataHandler = nullptr;

// Handler function for the /data endpoint
void handleData() {
  server.send(200, "text/plain", "This is the data endpoint.");
  Serial.println("Handled /data request.");
}

// Handler function to remove the /data handler
void handleRemoveData() {
  if (dataHandler != nullptr) {
    server.removeHandler(dataHandler);
    server.send(200, "text/plain", "Data handler removed.");
    Serial.println("Handler for /data has been removed.");
    dataHandler = nullptr; // Set pointer to null after removal
  } else {
    server.send(200, "text/plain", "Data handler was already removed or never added.");
    Serial.println("Attempted to remove handler, but it was already null.");
  }
}

// Handler for root path
void handleRoot() {
  server.send(200, "text/html", "<h1>AvantMaker.comESP32 Web Server</h1><p>Visit /data to get data.</p><p>Visit /removeData to disable the /data endpoint.</p>");
  Serial.println("Handled / request.");
}

// Handler for Not Found
void handleNotFound() {
  server.send(404, "text/plain", "404: Not Found");
  Serial.println("Handled 404 Not Found.");
}

void setup() {
  Serial.begin(115200);
  Serial.println();
  Serial.println("Connecting to WiFi...");

  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("WiFi connected.");
  Serial.print("IP Address: ");
  Serial.println(WiFi.localIP());

  // Register the root handler
  server.on("/", HTTP_GET, handleRoot);

  // Register the /data handler and store its pointer
  // Note the use of '&' before server.on() to get the address (pointer) of the returned RequestHandler object
  dataHandler = &server.on("/data", HTTP_GET, handleData);
  Serial.println("Registered handler for /data");

  // Register the handler to remove the /data handler
  server.on("/removeData", HTTP_GET, handleRemoveData);
  Serial.println("Registered handler for /removeData");

  // Register a Not Found handler
  server.onNotFound(handleNotFound);

  server.begin();
  Serial.println("HTTP server started.");
}

void loop() {
  server.handleClient();
  // You could add other tasks here
  // delay(10); // Small delay can be useful in some loops
}