[LiveComponent] Live Actions cannot handle file downloads

[richardhj]

As live actions are treated as regular controller actions, they should also support file responses.

#[LiveAction]
public function submit(): BinaryFileResponse
{
    $this->validate();

    return $this->file($this->exporter->generate($this->items));
}

Currently, file downloads are not downloaded but parsed..?

Edit (current workaround)

public function submit(UriSigner $uriSigner): Response
{
    $this->validate();


    $file = $this->exporter->generate($this->items)

    $url = $this->generateUrl('admin_download', ['file' => base64_encode($file)]);

    return $this->redirect($uriSigner->sign($url));
}

[smnandre]

Hello @richardhj

there is no support of File responses currently in LiveComponent

Couple of solutions:

• send a redirect response -> GET url of your response (what i'd do)
• use a standard action/URL instead of a live one (probably not the best there as it seems you need some form data)
• create a custom action in your Stimulus controller to handle the binary stream (but you may need to duplicate some code)

--

Some quotes cherry-picked from the RFC9110, in favor of the POST -> redirection -> GET solution

If one or more resources has been created on the origin server as a result of successfully processing a POST request, the origin server SHOULD send a 201 (Created) response containing a Location header field that provides an identifier for the primary resource created (Section 10.2.2) and a representation that describes the status of the request while referring to the new resource(s).

If the result of processing a POST would be equivalent to a representation of an existing resource, an origin server MAY redirect the user agent to that resource by sending a 303 (See Other) response with the existing resource's identifier in the Location field. This has the benefits of providing the user agent a resource identifier and transferring the representation via a method more amenable to shared caching

--

Now what seems weird to me is how the response seems handled and displayed in your example/capture... that may need some improvement / bug fixes :)

[richardhj]

Hi @smnandre, thats valuale information, I implemented a redirect to a "download controller" 👍 👍

However, that redirect must be uri-signed, so I can make sure that only "authorized" files can be downloaded.
Maybe there is a way, Live component may support content-disposition in the future? 😄

[norkunas]

same need here, so maybe this should be considered to be in core 🤔

[barbieswimcrew]

would be awesome if file response handling would work one day ❤️

[stefpe]

+1

[x-vlad-x]

+1

[sebbemunich]

+1

[richardhj]

Hey guys, this is not how OSS work and you are spamming other people's mailboxes.

[smnandre]

Hi @stefpe, @x-vlad-x, @sebbemunich,

I understand your desire to see this feature implemented. However, as @richardhj mentioned, this is an open-source project, so you can either:

• Open a pull request (PR) to add the feature.
• Ask your company to sponsor someone to develop it.
• Make a polite request for someone else to consider working on it.

If you want to support @barbieswimcrew's suggestion, thumbing up the first message in the issue is the best way, as it allows us to sort by this.

---

I performed a brief test with this method, which could serve as an implementation idea. This is similar to how Livewire implements this feature.

Here are some considerations for the implementation:

• Handle readable streams if possible.
• Ensure files do not remain in memory or the DOM unnecessarily.
• Prevent the creation of large blobs (e.g., 1TB) in the DOM.
• Verify the origin of the files (only accept local streams/files, perhaps with a custom header).
• Enforce that this occurs only after a user action (not on load or after an event).

However, implementing this will take some time, which I currently do not have, as we all work on this in our free time.

(and I still believe that redirecting to a file is a much cleaner solution 😄 )

[devath0]

This option would really be very useful.

[zefyx]

@smnandre, thank you for the following suggestion (and congrats for your place in the Symfony UX Core Team 👍)

there is no support of File responses currently in LiveComponent

Couple of solutions:

* send a redirect response -> GET url of your response (what i'd do)

Just in case someone found this topic and is trying to implement a download from a LiveComponent using a return new RedirectResponse() with something similar to the following code :

#[LiveAction]
    public function initiateDownload(
        UrlGeneratorInterface $urlGenerator,
    ): Response
    {

        $url = $urlGenerator->generate('app_document_download');
        return new RedirectResponse($url);
    }

<div{{ attributes }}>
    <button
            data-action="live#action"
            data-live-action-param="initiateDownload"
    >
        Export
    </button>
</div>

If turbo is enabled (it is if you have initialized your symfony project with --webapp) there is a strange behaviour (or not ?) : the url will be called twice : first from the live component (type fetch) then by turbo (type document)

If you share data between the live component and the controller route with a session and you manipulate this data (add/remove), you will have unexpected results (eg : $session->remove('some_session_key')) because the data will be changed on the first call and not in the state you expect in the second call : the one that return the document.

Adding the attribute data-turbo="false" (turbo doc) to the root of your live component will bypass this behaviour

<div{{ attributes }}
        data-turbo="false"
>
    <button
            data-action="live#action"
            data-live-action-param="initiateDownload"
    >
        Export
    </button>
</div>

The url of RedirectResponse() is now called only once

(on symfony 7.2.2 up to date at the time of this post)

[smnandre]

Hi @zefyx! Thank you for sharing this feedback (and the kind words).

We are working on a proper implementation of downloads with LiveComponent on the PR here #2483

But this is something that could be mentioned anyway on the documentation I think.

Probably just after we speak about file uploads, in a dedicated "Download" paragraph

Maybe just a paragraph ending with the HTML you provided here...
... would you have time to open a PR for this ?