Fix problematic Date fiels in shapefile

[cipri-tom]

Hi,

I have a shapefile which contains a Date field. This is returned as bytes, which is not writable to JSON.
Here is a PR which check which fields are dates and converts them to strings, using the same convention as pyShp.

It is related to this issue in pyShp.

Of course, the better fix would be that pyShp provides a way to represent dates as strings. Then, the whole shp_to_json() function would be only a call to reader.__geo_interface__.

On the same note, we can make the shp_to_json() function not write an auxiliary file. Or, ar least, it should be optional, since we can json.dumps and return that string directly. Would you be OK to refactor this method?

Thanks,
Ciprian

[cipri-tom]

I tried to run tests on my side, but they are failing as I cannot connect to earth-engine with the default way, only with initialization from service account.

Also, I tried to run flake8, but thre are a lot of warnings in places not related to these code changes.

[giswqs]

This is great! Thanks for the fix. And yes, we can make creating the geojson file optional. Pull request is welcome. Thanks.

[karimbahgat]

Just pushed new commits to pyshp to address this. Now, date fields are loaded into python date objects for convenience to the user as usual, but calls to geo_interface will automatically convert them back to the original date string, so that they are directly able to be json serialized. This means you can simply call .__geo_interface__ on the entire shapefile, or on each individual feature/shaperecord.

A minor correction regarding the previous behavior: Date fields were returned as datetime.date objects, as None if null-value, or as bytes if the datestring was faulty and could not be parsed. However, it's possible some null-values were not correctly identified and failed to bytestring, but I've now made this more robust.

Until I push this to a new release version, you can test it out from the latest GitHub repo.

[giswqs]

@karimbahgat Thanks for the fix.