Representing bytes[] into the input element by editing GIF-file ?

Why do you need to represent bytes field in thymeleaf? You don't need to put all of the member variables of the object for the form to get through.

If you want to edit Gif, you get all "good" changed data, like 'name', 'description'. And then before you save Gif, you take the old image of it, and put it to the Gif you are trying to update?

Does it make sense? Sometimes you can have situations where you want to change only specific property of object, like name, and there is no need to put all the rest of the data to thymeleaf. In this case you put to thymeleaf template only id and name, leaving the rest of the fields to be null.

Then All you do is take old Object from database, change his name to the new one, and update it. Without carrying around information of all his fields, but just taking the data from database.

That is if I understood your question correctly...

Let me show workaround how to change all the fields except image:

1. Add update(Gif gif) method on Service Layer, like this:

    @Override
    public void update(Gif gif) {
        Gif oldGif = gifDao.findById(gif.getId());
        gif.setBytes(oldGif.getBytes());
        gifDao.save(gif);
    }

1. Add the following to the GifController.updateGif method:

    @RequestMapping(value = "/gifs/{gifId}", method = RequestMethod.POST)
    public String updateGif(Gif gif,
                            @RequestParam MultipartFile file,
                            RedirectAttributes redirectAttributes) {
        // TODO: Update GIF if data is valid
        if (!file.isEmpty()) {
            gifService.save(gif, file);
        } else {
            System.out.println("file is empty");
            gifService.update(gif);
        }

This way we can use old image if file is empty and update Gif, and put new one if new image was uploaded. Coming back to the problem how to show existing image in input I don't know. May be Chris knows, may be Google... Have to dig more

Hi. I found this article, take a look:

http://stackoverflow.com/questions/1696877/how-to-set-a-value-to-a-file-input-in-html

I think we cannot set value of file to input theoretically not just in thymeleaf, due to security reasons. So that no one can change the value, otherwise they can steal from you, I guess. Which means we cannot pre-populate file input with value. I like answer with 25 votes:

Not an answer to your question (which others have answered), but if you want to have some edit functionality of an uploaded file field, what you probably want to do is:

• show the current value of this field by just printing the filename or URL, a clickable link to download it, or if it's an image: just show it, possibly as thumbnail
• the <input> tag to upload a new file
• a checkbox that, when checked, deletes the currently uploaded file. note that there's no way to upload an 'empty' file, so you need something like this to clear out the field's value