skyx skyx - 2 months ago 17
C Question

How to use esp8266WiFi Library GET request to obtain info from a website

I'm working on the esp8266-01 wifi module programmed with arduino IDE to send GET request to a URL and read the contents.
Trying to modify the below code which uses the esp8266WiFi library, I'm not clear what to replace for host. Should i put my URL in host or something else?
Also how to edit the line

client.print(String("GET ") + url + " HTTP/1.1\r\n" +
"Host: " + host + "\r\n" +
"Connection: close\r\n\r\n");


Thanks.

#include <ESP8266WiFi.h>

const char* ssid = "your-ssid";
const char* password = "your-password";

const char* host = "data.sparkfun.com";
const char* streamId = "....................";
const char* privateKey = "....................";

void setup() {
Serial.begin(115200);
delay(10);

// We start by connecting to a WiFi network

Serial.println();
Serial.println();
Serial.print("Connecting to ");
Serial.println(ssid);

WiFi.begin(ssid, password);

while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}

Serial.println("");
Serial.println("WiFi connected");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());
}

int value = 0;

void loop() {
delay(5000);
++value;

Serial.print("connecting to ");
Serial.println(host);

// Use WiFiClient class to create TCP connections
WiFiClient client;
const int httpPort = 80;
if (!client.connect(host, httpPort)) {
Serial.println("connection failed");
return;
}

// We now create a URI for the request
String url = "/input/";
url += streamId;
url += "?private_key=";
url += privateKey;
url += "&value=";
url += value;

Serial.print("Requesting URL: ");
Serial.println(url);

// This will send the request to the server
client.print(String("GET ") + url + " HTTP/1.1\r\n" +
"Host: " + host + "\r\n" +
"Connection: close\r\n\r\n");
unsigned long timeout = millis();
while (client.available() == 0) {
if (millis() - timeout > 5000) {
Serial.println(">>> Client Timeout !");
client.stop();
return;
}
}

// Read all the lines of the reply from server and print them to Serial
while(client.available()){
String line = client.readStringUntil('\r');
Serial.print(line);
}

Serial.println();
Serial.println("closing connection");
}

Answer

Your line client.print(String("GET ") + url + " HTTP/1.1\r\n" + "Host: " + host + "\r\n" + "Connection: close\r\n\r\n"); is OK. You don't need to change it.

For host you have to provide domain name or IP address. Eg. const char* host = "example.com";.

Example

If you want to get http://stackoverflow.com/questions/39707504/how-to-use-esp8266wifi-library-get-request-to-obtain-info-from-a-website you should have:

const char* host = "stackoverflow.com";
String url = "/questions/39707504/how-to-use-esp8266wifi-library-get-request-to-obtain-info-from-a-website";