Microsoft MakeCode

Lost main.ts code, is there a way to recover?

Arcade Help
#1

I was working on an experiment in JavaScript, and when I loaded the project today I got greeted by an empty Blocks screen, and the main.ts file is now empty :frowning:

This looks a bit similar to previous issues such as https://github.com/microsoft/pxt-arcade/issues/1855 and https://github.com/microsoft/pxt-arcade/issues/702, is there any current known bug that could trigger this? Iā€™m using the live version, and itā€™s possible that I had never opened the Blocks view while working on it previously until I closed the editor.

Separately, is there any way to recover the lost source code? I was poking around a bit in Chrome Dev Tools in Application / Storage, and I found the IndexedDB storage (_pouch_pxt-arcade / by-sequence (go to last page), but that also has the empty main.ts.

I still have UF2 files, and https://github.com/microsoft/uf2#embedding-sources mentions that the file format supports embedding sources - does Arcade do that, and if yes is there a tool to extract it?

Note to self: make sure to export or save as image regularly, I was trusting the editor to keep my work-in-progress safeā€¦

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#2

Edit: See UnsignedArduinoā€™s response, simply drag&drop the UF2 file into arcade.makecode.com, same as loading a saved image. Iā€™m keeping the unnecessarily complicated method below for curiosityā€™s sake.

The UF2 file does indeed contain a copy of the source :slight_smile:

Thereā€™s likely a cleaner way to do that, but hereā€™s how I got the data out using command line tools.

First confirm that the ā€œsourceā€ magic number is present - this part isnā€™t part of recovering, but I wanted to check if it has source at all:

$ fgrep -ba $'\x41\x14\x0E\x2F\xB8\x2F\xA2\xBB' FILE.uf2
495620:[binary stuff]{"compression":"LZMA"}

Use the uf2conv tool to get a binary file: https://github.com/microsoft/uf2/blob/master/utils/uf2conv.md

$./uf2conv.py ~/FILE.uf2 --convert --output FILE.bin

Load the file into a binary-clean editor, search for ā€œLZMAā€, delete everything up to and including the final } of the JSON header, and save to FILE_SOURCE.lzma. In my case, the first bytes of the compressed data was ]^@^@ or 5d 00 00 80 00 in hex.

Then use the lzma and jq tools to get the source back:

$ lzma -d < FILE_SOURCE.lzma > source.json
$ jq '.["main.ts"]' < source.json > recovered-main.ts

(The source actually contains an extra JSON header, but the extraction worked anyway.)

It should be possible to wrap this in a recovery tool, but I wanted to save the steps in case this helps someone else, or future me if I get bitten by such a bug againā€¦

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#3

You can load UF2 files just like images.

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#4

Ah, that would have been a lot easier :slight_smile: I guess I learned something along the way though.

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#5

We had a bug like that before where it would switch to blocks without decompiling in some cases and delete main.ts, but to my knowledge that was fixed ~ half a year ago and I havenā€™t seen it since then; any more details you have would be super helpful if you have them in case thereā€™s a sequence that regressed.

in case itā€™s helpful, one of the old ways to repro it if I recall correctly was to go from main.ts to another file (pxt.json or a locked file in an extension), then click the blocks toggle at the top; it wouldnā€™t notice there were edits made in ts and would just load up whatever was in the block file at that point.

And yes, dragging a uf2 onto the homescreen or using the import ā†’ import file button on the homescreen should both work :slight_smile:

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#6

I donā€™t remember the exact sequence, but I think it was something like this:

  • create a new project
  • switch to JavaScript
  • add a second source file with ā€œ+ā€ in explorer, use that for an added class
  • switch back between main.js and the second source js a few times. Donā€™t open Blocks mode.
  • close the editor
  • (later, after a computer restart) open the editor

At this point, the editor opened into an empty Blocks view.

#7

Interesting, thanks! Iā€™ll play around and see if I can find a way to repro, this is a very bad bug if itā€™s happening again!

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#8

Thanks for investigating! I didnā€™t end up losing anything since I had the UF2 file due to testing on hardware, but this could be nasty for someone whoā€™s only working with the emulator.

#9

This has happened to me before - and itā€™s one way to circumvent the code too large for blocks error!

#10

You can always ā€˜skip and go backā€™ if you put a syntax error into the ts and go to blocks (it will pop a dialog with ā€œDiscard and go to blocks or stay in javascript?ā€) but if it goes directly to blocks and throws stuff away without an optionā€¦ thatā€™s bad.