I would like to be able to tell if a site lets you upload files. I can think of two main ways sites do it and ideally I'd like to be able to detect both:
PhantomJS documentation has this example snippet:
var webPage = require('webpage');
var page = webPage.create();
page.uploadFile('input[name=image]', '/path/to/some/photo.jpg');
but it's not clear how I could figure out that input[name=image] actually supports uploading.
Currently, my crawlers are following all links and buttons on sites but I am not sure how to detect that "a file upload pop-up has been opened". The D&D case is even less clear to me. I need a solution for a single page and obviously I can then go and apply it to every page I pass.
UPDATE Turns out most of the time this does the trick:
document.querySelector('input[type=file]').click()
However, D&D areas aren't always clickable and you can't always assume [ondrop] will be present. Sometimes, the drop listener is added in code:
object.addEventListener("drop", myScript);
How can I check for presence of such elements then?
You can check if a form has enctype="multipart/form-data" or not. or search for input with type=file in html page.
AFAIK the best approach to upload files with selenium is to send the file to be uploaded directly to element located by this CSS Selector input[type=file].
So in order to check if some web page supports file uploading you can by checking if that page contains input[type=file] element.
This element is normally not visible and not interactable by GUI so you can only check it's existence, not visibility etc.
Nothing can get you 100%, but i think 99% it works with input[type=file] unless user wasn't creating it at runtime using javascript.
Or you can check for form's enctype but also it isn't always works as there's a good chance that user compress and changes the file into base64, then there will be no need for enctype to be multipart/form-data.
So input[type=file] is the best way.