Replies: 8 comments 13 replies
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Could you create the most minimal example? The main limitation is that we only have access to the stdlib and not any anvil module It might not work but it'll be fun trying |
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Yes I sure can make a clone. I was about to start building a test app for this anyway so I will do that with the idea to clone that here. |
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Ok so I have created a minimal example. The basic premise is that to upload lots of files/images we need a consistent internet connection. If there is no connection when the files are uploaded they should be stored locally until they can be uploaded. The example takes files from a If files are large or there are lots it takes a bit of time (but it doesn't time out since it is using client writable views). If this could be off loaded to a background process via a web worker then the main app can continue relatively unhindered. Ultimately it would be good to extend this functionality to entire table rows but for now being able to upload the files separately would be sufficient. I would be keen to make this work to include in Anvil Extras - something like this would have made my life a whole lot easier 2 years ago Please bear in mind files will be saved to the data tables so please don't upload anything sensitive if using the example link. |
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Wanna check this out - you'll need to adjust the url in the loader module to match the api endpoint url It will clone a local copy of anvil_labs because I found a couple of bugs when playing with this Let me know what you think |
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!!!! Its sooooo freaking Awesome!!!! Honestly Stu if you ever need a personal cheerleader - I am there, pompoms and all. Love it - now, how the heck do I use it 😂 So I am presuming we could use this to send anything JSONable right? Thank you for checking this out Stu - even this is immensely helpful so far. |
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yeah exactly - you could handle the api endpoint by creating a media object from the response body and then storing that in the table. An alternative is simply to wrap the saving mechanism you currently have with: from functools import wraps
def no_loading_indicator(fn):
@wraps(fn)
def wrapper(*args, **kws):
with anvil.server.no_loading_indicator:
return fn(*args, **kws)
return wrapper
...
@no_loading_indicator
def write_from_indexed_db_to_datatable (self, **event_args):
self.files_remaining = len(self.media_store)
...
Re errors with multiple tasks being launched - You can create a new worker or just wait for a task to be completed before trying run a new one. |
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This was my first approach but since the app is so anvil.server.call() intensive you literally end up waiting for pages to load since they require data from the server (and there is no spinner to indicate something is going on).
But they can't make server calls as they get queued.
As I understand it, the web worker works on a separate thread right? So the app just continue as per normal (presumably there is some minor impact to bandwidth or processor efficiency or something). In which case this web worker is ideal. I am rebuilding an inspection app over the next few days - are you happy for me to try work this into it? Edit: I have just confirmed that with the |
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yeah - that's the caveat - the server calls are queued. So yeah you're right - in that case the web worker is probably the right approach here! |
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Yeah absolutely. I've updated the module so you can use real anvil_labs rather than the local copy |
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Our entire company/app is experimental so that fits perfectly hahahaha Awesome - I will add it in and report back Thanks again Stu! |
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So I have got this working up to the point of the HTTP endpoint, but I am struggling to convert the request body into a prints: I notice in the Chorme Dev tools that looking at the Indexed_DB entry the content is stored as a |
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I think you just need to change the call signature to BlobMedia. Content type is first no? Or just use keyword arguments. |
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#facepalm Thank you Stu its working now. We have a little more to do but should be able to put this WebWorker through its paces in the next few days. |
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Hope it's ok to ask this here as it's pretty closely related to the discussion and work already done. @s-cork how difficult would it be to use a PWA Service worker background sync for this sort of update? That way the update should be able to cope with a loss of internet and still update even if the app is closed/no longer in foreground or the device is off(asleep) once internet returns. The App I'm developing requires a messaging function so the ability to enter a message when offline click send put the phone back in your pocket and have the message sent once the phone gets a connection is much preferable to only sending once you go back to the app (possibly hours or days later). This would truly make the offline usability of Anvil awesome!! |
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@s-cork Are you able to help me adjust the code to send a dict. I have the media working but have not been able to send a dict via http. I have tried to send it as a string which works but figured there was something I am missing in my understanding of the fetch api. |
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Yeah you'll just need to do something like Or convert to json before you send it to the worker. If you choose application/json then the body must be json. |
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Nailed it thanks Stu .. I had tried a bunch of other approaches but did not know about the |
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It seems that this WebWorker code has now stopped working. Thanks in advance. |
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Works for me. Here's a slightly updated clone - https://anvil.works/build#clone:6KH7IIUS22JMNW54=664RQKGADXDEV6KC4XPXNMPR You might want to add an error handler to the task in case there are errors that you're not seeing self.task.on_error = self.error_handler
def error_handler(self, error):
raise error |
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Thanks Stu, This updated version works for me but still cloning the original and replacing the endpoint url still has issues. In the failing app's logs I see this though. Two HTTP calls, 1 second apart with the same uuid of the file that is being loaded. The updated version shows no HTTP sessions at all but completes correctly (3 different sessions shown - all completed correctly) |
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The original version was only ever supposed to work in published version of the app (proof of concept). The current version gets the api endpoint associated with the current session. So it's a bit cleaner. And should work in debug sessions. For the logs - there's probably a same origin thing going on in the debug session. If debug sessions worked before and not now - then I'm not sure. |
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Not that I know anything about web workers but I think I have a use case and would like some guidance on whether I am barking up the right tree or this is in fact a fire hydrant.
I have an app that carries out inspections, large inspections. typically 100 odd questions with 50 or 60 photos to be attached which are temporarily saved to IndexedDB before upload.
The problem we have faced is that uploading that volume of data needs to be done in chunks to avoid time outs and this locks up the app while upload takes place.
Could I use a web worker to handle this in the background leaving the user free to move on to other tasks?
Could I also use the web worker to check whether there is an internet connection before proceeding?
Thanks in advance.
Rick.
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