How are you all handling file uploads in the Web Messaging SDK? I’m trying to let customers attach PDFs, but the SDK doesn’t seem to expose a clear way to validate MIME types or enforce size limits before the upload hits the API. The docs are vague on this. If I try to send a large image, it just fails silently or hangs. Is there a specific event listener or config option I’m missing to intercept the file object?
// Intercept the file before it hits the SDK uploader
const fileInput = document.getElementById('file-upload');
const maxSize = 5 * 1024 * 1024; // 5MB limit
const allowedTypes = ['application/pdf', 'image/png', 'image/jpeg'];
fileInput.addEventListener('change', (event) => {
const file = event.target.files[0];
if (!file) return;
// Check MIME type first
if (!allowedTypes.includes(file.type)) {
alert('Invalid file type. Please upload PDF or images only.');
event.target.value = ''; // Clear the input
return;
}
// Check file size
if (file.size > maxSize) {
alert('File is too large. Max size is 5MB.');
event.target.value = '';
return;
}
// Now pass the valid file to your custom attachment handler or SDK method
// platformClient.conversations().addConversationMessage(..., { attachment: file })
});
The SDK doesn’t validate MIME types for you because it treats the attachment as a generic binary blob until it hits the Genesys Cloud API. If you let the SDK handle the upload directly without pre-checking, you’re relying on the server-side validation which can take a few seconds to fail. That’s probably why you’re seeing those hangs or silent failures.
Since you’re likely using a custom file input element to trigger the upload, you need to intercept the change event on that DOM element before the SDK even sees the file. The code above shows how to do a simple client-side check. It looks at the file.type property which is usually accurate for standard PDFs and images.
One thing to keep in mind is that file.type can sometimes be empty if the browser doesn’t recognize the extension. If you’re dealing with obscure file types, you might need to check the file extension manually by splitting the filename string. But for standard PDFs and images, checking the MIME type against a whitelist like the one in the snippet works well.
Also make sure your OAuth token has the consent:write scope if you’re uploading on behalf of a user, otherwise the API will reject it regardless of how clean your client-side validation is. The Web Messaging SDK handles the token refresh internally, but if you’re calling the REST API directly for the attachment part, you need to ensure the scope is present.