HTTP POST problem

[MohammadMokhalled]

I have have a problem to send something use POST method and then read the page. my code is below:

    #include <Arduino.h>
    #include <ESP8266WiFi.h>
    #include <ESP8266WiFiMulti.h>
    #include <ESP8266HTTPClient.h>
    #define USE_SERIAL Serial
   
    ESP8266WiFiMulti WiFiMulti;
    HTTPClient http;
 void setup() {
  USE_SERIAL.begin(115200);
 // USE_SERIAL.setDebugOutput(true);
 USE_SERIAL.println();
 USE_SERIAL.println();
 USE_SERIAL.println();

for(uint8_t t = 4; t > 0; t--) {
    USE_SERIAL.printf("[SETUP] WAIT %d...\n", t);
    USE_SERIAL.flush();
    delay(1000);
}
WiFiMulti.addAP("SSID", "PASSWORD");
 }

      void loop() {
     // wait for WiFi connection

    if((WiFiMulti.run() == WL_CONNECTED)) {
    HTTPClient http;
    USE_SERIAL.print("[HTTP] begin...\n");
    // configure traged server and url
    http.begin("http://server/test.php"); //HTTP

    http.addHeader("Content-Type", "application/x-www-form-urlencoded");
     http.POST("id=s1&api=123456789");
     http.writeToStream(&Serial);
     http.end();

    USE_SERIAL.print("[HTTP] GET...\n");
    // start connection and send HTTP header
    int httpCode = http.GET();

    // httpCode will be negative on error
    if(httpCode > 0) {
        // HTTP header has been send and Server response header has been handled
        USE_SERIAL.printf("[HTTP] GET... code: %d\n", httpCode);

        // file found at server
        if(httpCode == HTTP_CODE_OK) {
            String payload = http.getString();
            USE_SERIAL.println(payload);
        }
    } else {
        USE_SERIAL.printf("[HTTP] GET... failed, error: %s\n", http.errorToString(httpCode).c_str());
    }

    http.end();
}

delay(10000);}

when i run it i get the 411 error code. whats wrong here? how can i solve it?

[maurotrochez]

Hi @GolPesar132 . Do you test this request in POSTMAN? is for discard that the service in php is good or you missing any parameters.

[MohammadMokhalled]

No I didn't test in postman. Because i had a host for this. I didn't miss any parameter. I don't know what do you mean about "is for discard that the service in php is good".

[MohammadMokhalled]

I test it use POSTMAN and its OK. I don't know why it tell give this error. how can I solve it?

[maurotrochez]

Try add another header.
http.addHeader("Content-Length", 0);
or
String payload = "id=s1&api=123456789";
http.addHeader("Content-Length", payload.length());

[MohammadMokhalled]

I try both of them but these don't work again.

[maurotrochez]

Try using WifiClient, like in this comment 👍

[jamesmarlowe]

The relevant section of your code is right here:

    // configure traged server and url
    http.begin("http://server/test.php"); //HTTP

    http.addHeader("Content-Type", "application/x-www-form-urlencoded");
     http.POST("id=s1&api=123456789");
     http.writeToStream(&Serial);
     http.end();

    USE_SERIAL.print("[HTTP] GET...\n");
    // start connection and send HTTP header
    int httpCode = http.GET();
    ...

You set up your POST, then erroneously http.writeToStream(&Serial); and http.end(); before going on to do a GET request and checking the status code of that.

To fix your code you will need to rethink what you are doing, start by removing your first http.end() and the http.GET().

[MohammadMokhalled]

@jamesmarlowe Thanks for your guide.
I remove first http.end(); and change http.POST("id=s1&api=123456789"); to int httpCode =http.POST("id=s1&api=123456789"); and remove http.GET(). It's wrong again. What should I do now?

[jamesmarlowe]

No problem, it's impossible to say what's wrong without your environment, but perhaps a complete POST example will help you see what you are missing: https://github.com/esp8266/Arduino/blob/master/tests/device/test_http_client/test_http_client.ino#L52

[devyte]

@GolPesar132 this is not the right place to ask for help with your particular code. This is an issue tracker, meant for tracking issues in the core code. If you still need help, please refer to a community forum.
Closing per #3655 .