Uploading file using Google Apps Script using HtmlService
Have the button run the server side function using google.script.run, passing in the entire form as the only parameter. (Inside the button's onClick, 'this' is the button, so 'this.parentNode' is the form.) Make sure to give the file input a name.
<html>
<body>
<form>
<input type="file" name="theFile">
<input type="hidden" name="anExample">
<input type="button" onclick="google.script.run.serverFunc(this.parentNode)">
</form>
</body>
</html>
On the server, have your form handling function take one parameter - the form itself. The HTML form from the client code will be transformed into an equivalent JavaScript object where all named fields are string properties, except for files which will be blobs.
function doGet() {
return HtmlService.createHtmlOutputFromFile('myPage');
}
function serverFunc(theForm) {
var anExampleText = theForm.anExample; // This is a string
var fileBlob = theForm.theFile; // This is a Blob.
var adoc = DocsList.createFile(fileBlob);
return adoc.getUrl();
}
If you actually want to use that URL you are generating and returning, be sure to add a success handler to the google.script call. You can modify it like this:
// Defined somewhere before the form
function handler(url) {
// Do something with the url.
}
<input type="button" onclick=
"google.script.run.withSuccessHandler(handler).serverFunc(this.parentNode)">