Arduino: getting data from a POST request

[sukhmeet032795]

i have a url /wifiSetup. Whenever a user sends post request to the esp, some json is sent along with
the url. I want to get the json content in my handler

Code:

ESP8266WebServer server1(80);
server1.on("/wifiSetup", wifiSetup);

void wifiSetup(){

WiFiClient client = server.available();
while(client.available()) {
Serial.print(client.read()); // print client data
}
}

This return me POST /wifiSetup HTTP/1.1
I want the json content sent along with the request. How can i get the json?

[sukhmeet032795]

For those who are not able to figure it out:

Code:

include

ESP8266WebServer server(80); //creating the server at port 80

void setup() {
Serial.begin(115200);
server.on("/yourURL", function);

//configuring the server wherein you configure your url and function name, you can also mention your method(GET,POST..) if u want i.e server.on("/yourURL", method,function);

server.begin();
}

void function() {
//do something
String varname = server.arg("abc"); //this lets you access the value using the key as you have set in your json for ex:

json={'body':'foo'}
so you can access the value of body by using server.arg('body');
}

void loop() {
server.handleClient(); //this is required for handling the incoming requests
}

Now find your wifi local ip and make a request at the particular ip and make requests. For more help refer:

https://github.com/esp8266/Arduino/blob/a5c3aea98ee4cb445b973d2970dcbeefc52216c1/libraries/ESP8266WebServer/src/ESP8266WebServer.cpp

[themakerbro]

Hey @sukhmeet032795, I'm having problems accessing my JSON data using

server.arg("abc");

It just shows as empty, any chance you can post a simple example?

[bkomac]

Try

StaticJsonBuffer<200> jsonBuffer;
JsonObject& root = jsonBuffer.parseObject(server.arg("plain"));

[JBarna]

For anyone who may be interested, the ESP8266WebServer library does not support parsing JSON. You can see in the source code here that it supports data with MIME types application/x-www-form-urlencoded and multipart/....

So if you want to continue using JSON, you will need to use a jsonBuffer as @bkomac has noted and you can access the JSON string through server.arg("plain");

Otherwise, you can send your data in the supported MIME types.

Example using application/x-www-form-urlencoded
On your webpage you'd send an AJAX request as so

var xhr = new XMLHttpRequest();
xhr.open('post', '/postUrl');
xhr.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');
xhr.send('key1=value1&key2=value2');

Then on the server you'd access the data as so

String val1 = server.arg("key1");
String val2 = server.arg("key2");

[vladbalanescu]

Anyone experiencing this?

[devyte]

Try this:
String val1 = server.arg("key1");
String val2 = server.arg("key2");
=>
String val1(server.arg("key1"));
String val2(server.arg("key2"));

From what I've seen, build issues like this usually come from corrupted/bad installation, but in this case that's just a guess. I don't see that error when building my code.

[vladbalanescu]

Nope, still the same result

[devyte]

Oh oops. It says server, shouldn't it be webServer?

[vladbalanescu]

Yes, that is true. Thanks a lot for that spot. My huge mistake there, it was webServer in my case

[rammanoj]

I am sending a request int th following way (using curl)

  curl --request GET --data '{"asd": "asdasd"}' http://192.168.43.141/test

But I am not sure why I can't find any data in args, when I just print Serial.println(server.args()) it prints empty, and I also tried with Serial.println(server.arg("plain")); also prints nothing. I am not sure how the JSON data I sent is getting handled ??

[pcbtborges]

Hi, what libraries are required to use server.arg?
All I have is WiFiServer server(80); and it says:
'class WiFiServer' has no member named 'arg'

I am getting all the data I need (SEE BOLD TEXT) when my ESP32webServer gets JSON from a web browser but, so far, I am unable to get to the JSON data on the ESP32 side.

My Problem is:
Get to the JSON data arriving from the browser.

What is displayed at the ESP32 console is:

`New Client.
GET /?wifiSsid=Skynet&wifiPass=sssssss&delayPrimFoto=sdfgsdg&delayEntreFotos=sfdgsdf&timeGMT=-3&smtpServer=hhhhhhh&smtpUser=jjjjjjj&smtpPass=kkkkkkk&emailto=sfdgsd&emailTitle=gsdfgsdf&emailMessage=&ftpServer=&ftpUser=&ftpPass= HTTP/1.1
Host: 192.168.4.1
Connection: keep-alive
Upgrade-Insecure-Requests: 1
DNT: 1
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/77.0.3865.90 Safari/537.36
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,/;q=0.8,application/signed-exchange;v=b3
Referer: http://192.168.4.1/?wifiSsid=Skynet&wifiPass=babacabaca&delayPrimFoto=1&delayEntreFotos=3&timeGMT=-3&sendtoemail=checked&smtpServer=&smtpUser=&smtpPass=&emailto=&emailTitle=&emailMessage=&ftpServer=&ftpUser=&ftpPass=
Accept-Encoding: gzip, deflate
Accept-Language: en-US,en;q=0.9,pt;q=0.8,sv;q=0.7,es;q=0.6

Client disconnected.
`
Assistance welcome
Paulo

[devyte]

@pcbtborges wrong repo, this is for the esp8266, not the esp32.

[pcbtborges]

Ok, I see, but I was convinced the problem applies for both.
Thanks

[devyte]

That's possible, but the code base, repo, dev teams, and policies are very different. If true for our esp8266, please open a new issue and fill out the required info.

[earlephilhower]

WiFiServer is NOT a web HTTP class. It's a basic TCP socket class. SEnds and received raw bytes.

ESP8266WebServer or ESP8266HttpClient are the HTTP protocol classes.

[pcbtborges]

Hi, thanks, I posted this question on the Espressif forum as well.
"WiFiServer is NOT a web HTTP class."
I did realized that after some research.
But I reached the following command:
clientPayload = header.substring(header.indexOf("GET /?")+6,header.indexOf("HTTP/1.1"));
And with that I successfully extracted the long string that has everything I need.
Now, it is going to be a lot of work to split all that out to the variable I need.
I would prefer to use a more professional approach like JSON but I still lack the understanding to switch from WiFiServer to a real web server library.
How would I extract the JSON from the payload I get from the customer browser?

Sorry for posting on a "closed" topic that in fact is for ESP8266 but that was the one I found to be the closest match for my problem. It would be a waste to live this knowledge unused.

Thanks everyone.