multipart/form-data - large file upload using http client

[AjitSingh]

Hi,
i have a query is it possible to upload the file using http-client using esp32. i have some idea about same that in have to use mutlipart/form-data. file size can varies upto 24 MB.
if possible how to achive it?

[mayur009]

hello ajitsingh !

you can use the method given below :

void upload_file(){
// Open WAV file from SD card
File file = SD.open("/" + fileName, FILE_READ); // Removed unnecessary String() conversion
if (!file) {
Serial.println("Failed to open file for reading");
return;
}

file.seek(0); // Reset file pointer to the beginning

// Clear formData string
formData = "";

// Get file size
int fileSize = file.size();
int numIterations = fileSize / 4096;
if (fileSize % 4096 != 0) {
numIterations++; // Add one more iteration for the remaining bytes
}

Serial.print("File size in bytes: ");
Serial.println(fileSize);
Serial.print("Number of iterations: ");
Serial.println(numIterations);

// Connect to server
if (!client.connect("server", port)) {
Serial.println("Connection failed!");
file.close();
return;
}
Serial.println("Connected to server");
Serial.println(fileName);
Serial.println(meetingTitle);

formData += "--" + boundary + "\r\n";
formData += "Content-Disposition: form-data; name=\"user_id\"\r\n\r\n";
formData += userId + "\r\n";

formData += "--" + boundary + "\r\n";
formData += "Content-Disposition: form-data; name=\"meeting_title\"\r\n\r\n";
formData += meetingTitle + "\r\n";

formData += "--" + boundary + "\r\n";
Serial.println(fileName);
formData += "Content-Disposition: form-data; name=\"meeting_audio\"; filename=\"" + fileName + "\"\r\n";
formData += "Content-Type: audio/wav\r\n\r\n";

String footer = "\r\n--" + boundary + "--\r\n";

int contentLength = formData.length() + file.size() + footer.length();

// Send POST request with Content-Length header
client.print("POST /save_audio HTTP/1.1\r\n");
client.print("Host: server:port\r\n");
client.print("Cache-Control: no-cache\r\n");
client.print("Content-Type: multipart/form-data; boundary=" + boundary + "\r\n");
client.print("Content-Length: " + String(contentLength) + "\r\n\r\n");

// Send form data
client.print(formData);

// Send file content
const int bufferSize = 4096;
byte buffer[bufferSize];
int bytesRead = 0;

int z = 0;
Serial.println(fileName);
while (file.available()) {
bytesRead = file.readBytes((char*)buffer, bufferSize);
client.write(buffer, bytesRead);
z++;
Serial.print(z);
Serial.print(" ");
}
file.close();
Serial.println();
Serial.println(z);
// Send footer
client.print(footer);

String line = client.readStringUntil('{');
Serial.println(line);

String serverRes = client.readStringUntil('}');
Serial.println("Server response: " + serverRes);

client.stop();

delay(10000); // Wait for 1 minute before sending
}