An event is fired twice with data-on-signal-patch on a file input

[kitharoidos]

Bug Report

I need to send an HTTP request to the backend whenever an image is uploaded, hence the following code:

<input data-bind="upload__profile-avatar.files" data-class-error="$app__error.upload__profile-avatar.files" data-on-signal-patch="console.log('Ahoj!'); @post('/profiles.add.avatar.upload')" data-on-signal-patch-filter="{include: /^upload__profile-avatar.files$/}" id="profile-avatar-input" type="file">

Unfortunately, the event is fired twice, that is, "Ahoj!" is printed twice to the console each time an image is uploaded.

Datastar Version

v1.0.0-RC.4

[bencroker]

My guess is that the signal is patched once initially, and then again after the promise to upload is complete, but @jmstevers can better confirm this..

[kitharoidos]

My guess is that the signal is patched once initially, and then again after the promise to upload is complete, but @jmstevers can better confirm this..

Thanks for your reply! Is there a workaround until this is fixed?

[gazpachoking]

I think this is because the bind plugin watches both the 'changed' and 'input' event, which are both fired at once for a file input, and the signals are updated after both.

[jmstevers]

If @gazpachoking is correct in that the signal is being updated on input and change then that would make sense since the file signal is an array which is an object which is always not equal to itself. So the signal gets updated even though the value is the same because we dont diff objects when setting signals outside of PatchSignals yet.

[gazpachoking]

I think for file inputs there isn't really a difference between those two events, so we could probably drop watching 'input'. (I'm not sure if this is universally true across all browsers though.) If we want something like #1032 that would be a problem though, as we'd need to catch both events to make sure other subscribers to either event end up waiting for the signals to be updated.

[kitharoidos]

Is there any chance of this being fixed before September? Our app using DataStar (from Clojure) is being deployed for client's testing at the beginning of September. Alternatively, is there a workaround? I tried listening for the "change" event directly, but there I stumbled upon the other issue - the event being fired before the signal is updated. The problem I'm trying to solve is that I need the uploaded files to be appended and not replaced - hence, I need to store the uploaded files somewhere outside the "files" signal. Thanks in advance!

[bencroker]

#1041 is planned for the next release, at which point we’ll circle back on this too. We’re in no rush though, so if you need urgent support then please get in touch at support@starfederation.dev

[kitharoidos]

#1041 is planned for the next release, at which point we’ll circle back on this too. We’re in no rush though, so if you need urgent support then please get in touch at support@starfederation.dev

No worries, I came up with a workaround - generating uploaded image UUIDs from file names. This works well in our case as the images are upserted to Datomic based on the UUIDs.