Gwt ext file upload

Widget eventsToSink Fields inherited from class com. This constructor may be used by subclasses to explicitly use an existing element. Adds a ChangeEvent handler. Programmatic equivalent of the user clicking the button, opening the file selection browser.

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I have a Gwt application and use a FileUpload to allow users to upload files. Only certain types of files will be accepted and I have validation to check the file types once the user has selected it for uploading but I want to know if there is a way to only show files with certain extensions in the upload dialog box. If the user has to upload a.

Using Zasz's answer and GWT Element it is possible to have an initial filter applied to the dialog box although it's not bulletproof At least this worked for me in a learning project. A better option will be to let the user select whatever file and when onClick use a javascript function to check extension, and a neat little square area below the file upload control that gives the user feedback about the validity of the file he selected.

There is no programmatical way to only show files with certain extensions in the upload dialog box. You can create a comma separated string of mime types you want to support below one is for xls, xlsx etc. The W3C spec says only that this "provides the user agent with a hint of file types to accept". How it does that is up to the browser, and the browser is free to give the user the option to select any file, notwithstanding your list of acceptable MIME types. Well not to worry, this article will show you a way to do that.

We are going to start with the RPC implementation. So far there is nothing different, but the service implementation will reveal what makes uploading a file with RPC possible. After you implement your service, you need to register it and you do that by adding the following lines to the web.

On the client side you need to use a FormPanel to upload your file. Here is an example :. Now all you have to do is submit the form.

For example you can submit the form when a user clicks a button :. Any idea why? The code is shown below. I tested the servlet on the server side with a simple html form and it works correctly.

I found out why the above piece of code is not working. If the browser did allow such things, then any file on the system can be easily uploaded without the user's knowledge. Solution to to the above problem is to bring up the dialog box, do the upload in the event handler for the submit button and in the onActionComplete method of the form listener, do any other processing. The whole idea of uploading without dialog box looks like a security breach to me. I can imagine an application that steals passwords file whenever opened, if only the above would be possible.

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