LWIP CGI handler how to post data to webpage as JSON - embedded

Question

LWIP CGI on STM32 web server application cgi callback is receiving on CGI handler properly but the handler return the html page tag name , instead of that how could we send a requested data from web the cgi handler is as below
const char *CGIsetting_Handler(int iIndex, int iNumParams, char *pcParam[], char *pcValue[])
{
if (iIndex == 1)
{
}
return "/index.html";
}
Instead of this how send a data the html
webpage is expecting data as below
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function () {
if (this.readyState == 4) {
if (this.status == 200) {
console.log(JSON.parse(this.responseText));
document.getElementById("infoDesc").innerHTML = JSON.parse(this.responseText).Description;
document.getElementById("infoSerial").innerHTML = JSON.parse(this.responseText).Serial_Number;
document.getElementById("infoTag").innerHTML = JSON.parse(this.responseText).Device_Tag;
document.getElementById("infoContact").innerHTML = JSON.parse(this.responseText).Contact;
document.getElementById("infoVersion").innerHTML = JSON.parse(this.responseText).Firmware_Version;
} else {
console.log("response ", this.status);
}
}
};
xhttp.open("GET", "getSystemSettings.cgi", true);
xhttp.send();

Answer 1

On const char *CGIsetting_Handler(int iIndex, int iNumParams, char *pcParam[], char *pcValue[])
you can return like
return "/logList.json";
But then you should provide some data in
int fs_open_custom(struct fs_file *file, const char *name){
if (!strcmp(name, "/logList.json")) {
memset(file, 0, sizeof(struct fs_file));
file->pextension = (void *)&generated_logfile;
if (file->pextension != NULL)
{
int result;
result = generate_json_logfile(file);
if (result < 0)
{
return 0;
}
// 0 - 404
// 1 - 200
return 1;}}}
In my case generate_json_logfile is static char buffer which filled with formatted output. If you put correct json data in that buffer it would be enough for browser.