How do I get the request params from a ESPAsyncWebServer?

Question

I currently have the following code

server.on("/on", HTTP_POST, [](AsyncWebServerRequest *request) {
    Serial.println("ON hit.");
    String message;
    Serial.println(request->url());
    if (request->hasParam("device"))
    {
        message = request->getParam("device")->value();
    }
    else
    {
        message = " not specified";
    }
    request->send(200, "text/plain", "On, GET: " + message);
    Serial.print("Device ");
    Serial.println(message);
....

When sending in a request I get the out put, "Device not specified".

I take a look at the request-params() which gives me back a count of params that are in there and it's returning 1. I write this out:

server.on("/off", HTTP_POST, [](AsyncWebServerRequest *request) {
    Serial.println("OFF hit.");
    String message;
    int params = request->params();
    Serial.printf("%d params sent in\n", params);
    for (int i = 0; i < params; i++)
    {
        AsyncWebParameter *p = request->getParam(i);
        if (p->isFile())
        {
            Serial.printf("_FILE[%s]: %s, size: %u", p->name().c_str(), p->value().c_str(), p->size());
        }
        else if (p->isPost())
        {
            Serial.printf("_POST[%s]: %s", p->name().c_str(), p->value().c_str());
        }
        else
        {
            Serial.printf("_GET[%s]: %s", p->name().c_str(), p->value().c_str());
        }
    }
    if (request->hasParam("device"))
    {
        message = request->getParam("device")->value();
    }
    else
    {
        message = "not specified";
    }
    request->send(200, "text/plain", "Off, GET: " + message);
    Serial.print("Device ");
    Serial.println(message);

and get the output now of

1 params sent in
_POST[device]: puddle
Device not specified

If I try to do something like request->getParam(0)->value().c_str() I get a stack dump of a bunch of hex values that I have no idea what it means: but it looks like a big fat error.

usually params are for GET while POST has a separate interface — dandavis, Oct 04 '18 at 16:09
@Juraj that was it. Want to make an answer? Lol, feel pretty silly. — rball, Oct 05 '18 at 03:52
just in case, someone finds this snipplet: In addition to @Juraj (correct) answer: If you want to access this param you also have to inform the function, that you want the url parameters: `message = request->getParam("device", true)->value();` — Dakkar, May 15 '20 at 17:09

Juraj · Accepted Answer · 2018-10-05T08:51:07.850

3

For POST request the hasParam needs to know if you want to test the url parameters or x-www-form-urlencoded parameters in body of the POST request. The second parameter of the hasParam is boolean post and it has default value false. Use hasParam("device", true).

edited Oct 05 '18 at 08:51

answered Oct 05 '18 at 05:28

Juraj

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How do I get the request params from a ESPAsyncWebServer?

1 Answers1