ESP8266 Community Forum

- Sun May 31, 2015 12:42 pm #19050 Can someone explain how to grab data from a URL variable? In PHP, when you navigate to a page (http://www.domain.com/index.php?id=1) you can use $_GET['id'].

If I have the ESP8266 hosting the page, what do I need to do to grab the value of 'id'?

- Mon Jun 01, 2015 6:33 am #19106 Using Arduino IDE you can use ESP8266WiFi library to easily parse the URL. the following code can be found in the WiFiWebServer example:

Code: Select allWiFiClient client = server.available();
  if (!client) {
    return;
  }
 
  // Wait until the client sends some data
  Serial.println("new client");
  while(!client.available()){
    delay(1);
  }
 
  // Read the first line of the request
  String req = client.readStringUntil('\r');
  Serial.println(req);
  client.flush();
 
  // Match the request
  int val;
  if (req.indexOf("/gpio/0") != -1)
    val = 0;
  else if (req.indexOf("/gpio/1") != -1)
    val = 1;
  else {
    Serial.println("invalid request");
    client.stop();
    return;
  }

So you just switch req.indexOf() to whatever you are looking for (in this case "id=") and then parse req to get the id value. There are of course better ways of doing it, but this seems to me to be the easiest.

- Mon Jun 01, 2015 7:50 pm #19171 Sorry, I should have put more detail into the question.

I'm looking to use only the ESP8266 SoC. I was reading a tutorial on Adafruit that has the following code:

Code: Select all
/* DHTServer - ESP8266 Webserver with a DHT sensor as an input
 
   Based on ESP8266Webserver, DHTexample, and BlinkWithoutDelay (thank you)
 
   Version 1.0  5/3/2014  Version 1.0   Mike Barela for Adafruit Industries
*/
#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <ESP8266WebServer.h>
#include <DHT.h>
#define DHTTYPE DHT22
#define DHTPIN  2
 
const char* ssid     = "YourRouterID";
const char* password = "YourRouterPassword";
 
ESP8266WebServer server(80);
 
// Initialize DHT sensor
// NOTE: For working with a faster than ATmega328p 16 MHz Arduino chip, like an ESP8266,
// you need to increase the threshold for cycle counts considered a 1 or 0.
// You can do this by passing a 3rd parameter for this threshold.  It's a bit
// of fiddling to find the right value, but in general the faster the CPU the
// higher the value.  The default for a 16mhz AVR is a value of 6.  For an
// Arduino Due that runs at 84mhz a value of 30 works.
// This is for the ESP8266 processor on ESP-01
DHT dht(DHTPIN, DHTTYPE, 11); // 11 works fine for ESP8266
 
float humidity, temp_f;  // Values read from sensor
String webString="";     // String to display
// Generally, you should use "unsigned long" for variables that hold time
unsigned long previousMillis = 0;        // will store last temp was read
const long interval = 2000;              // interval at which to read sensor
 
void handle_root() {
  server.send(200, "text/plain", "Hello from the weather esp8266, read from /temp or /humidity");
  delay(100);
}
 
void setup(void)
{
  // You can open the Arduino IDE Serial Monitor window to see what the code is doing
  Serial.begin(115200);  // Serial connection from ESP-01 via 3.3v console cable
  dht.begin();           // initialize temperature sensor
 
  // Connect to WiFi network
  WiFi.begin(ssid, password);
  Serial.print("\n\r \n\rWorking to connect");
 
  // Wait for connection
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("DHT Weather Reading Server");
  Serial.print("Connected to ");
  Serial.println(ssid);
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());
   
  server.on("/", handle_root);
 
  server.on("/temp", [](){  // if you add this subdirectory to your webserver call, you get text below :)
    gettemperature();       // read sensor
    webString="Temperature: "+String((int)temp_f)+" F";   // Arduino has a hard time with float to string
    server.send(200, "text/plain", webString);            // send to someones browser when asked
  });
 
  server.on("/humidity", [](){  // if you add this subdirectory to your webserver call, you get text below :)
    gettemperature();           // read sensor
    webString="Humidity: "+String((int)humidity)+"%";
    server.send(200, "text/plain", webString);               // send to someones browser when asked
  });
 
  server.begin();
  Serial.println("HTTP server started");
}
 
void loop(void)
{
  server.handleClient();
}
 
void gettemperature() {
  // Wait at least 2 seconds seconds between measurements.
  // if the difference between the current time and last time you read
  // the sensor is bigger than the interval you set, read the sensor
  // Works better than delay for things happening elsewhere also
  unsigned long currentMillis = millis();
 
  if(currentMillis - previousMillis >= interval) {
    // save the last time you read the sensor
    previousMillis = currentMillis;   
 
    // Reading temperature for humidity takes about 250 milliseconds!
    // Sensor readings may also be up to 2 seconds 'old' (it's a very slow sensor)
    humidity = dht.readHumidity();          // Read humidity (percent)
    temp_f = dht.readTemperature(true);     // Read temperature as Fahrenheit
    // Check if any reads failed and exit early (to try again).
    if (isnan(humidity) || isnan(temp_f)) {
      Serial.println("Failed to read from DHT sensor!");
      return;
    }
  }
}


I have already taken all Arduino related code out...
How can I modify this code to use the GET method (or POST) instead of having to create multiple lines of code for each value I could possibly send?