[x3d-public] Python X3D JSON schema validator (beta test release) *include metaschema validation*. Uses fastjsonschema

[John Carlson]

A friend wrote a loop to generate versions of X3D JSON Schemas. He wrote 
the loop in python.  I have modified the loop to create schema 
validators in python.  The code and products are checked into 
X3DJSONLD/src/main/python. There are examples of using python scripts 
generated from the validator for 3.3 and 4.0.

If someone would like to, they can develop a script for Command Prompt 
or PowerShell based on this python script.   I don't know if python on 
windows does any mapping from Linux to Windows.

You will need to install fastjsonschema first.  pip3 comes with python3:


$ pip3 install fastjsonschema

And install jsonlint (use your favorite node.js package manager) for 
pretty printing:

|$ npm install jsonlint -g |

You may have better results using the schema validator directly as far 
as getting good error messages.  I haven't figured out how to do that 
yet (exercise left to the reader). Right now, the python validators 
throws an ugly python error when running python (of course, to be expected).


What I have shown is the generated schemas pass draft-07 built into a 
potential build script, and potential for speeding up python X3D JSON 
validation.


I know it's very complex, but *well documented* I think.

I am mainly sending a link due to various mail filters messing up 
filenames with embedded host names. Here's the code:

https://github.com/coderextreme/X3DJSONLD/blob/master/src/main/python/generateSchemas.py

One should run the script in the X3DJSONLD/src/main/python folder.

Usage to validate a X3D 4.0 JSON file (python script found online next 
to generateSchemas.py):

python3 validate40.py < 4.0_file_name.json

So you can drop the JSON schema entirely with python, if you wish. 
AFAICT, right now.  This possibly would be advantageous to an x3d.py 
JSON "typeless" loader.

I don't know if we're close to reading a X3D JSON file into a python X3D 
model with python.    That's probably still a ways out, I think.  Of 
course, one can read a JSON file already in python. So these validators 
provide a bit of type-safety in the short term, when converting X3D JSON 
to a X3D model in python.   That is, it's easier to write a validator in 
the short term, since it's pretty much a series of commands to the 
operating system shell, and a lot of code is available for validating.

Be warned that this package generates an runs unchecked (by me) python, 
so you may want to use care.

generateSchemas.py generates the following files:

 > draft07.py
 > validate07.py
 > ../schema/x3d-{version}-JSONSchema.json
 > schemaparser{schemacodeversion}.py
 > validate{schemacodeversion}.py

be sure to make backups, fork my repository, if you run the 
generateSchemas.py script.   The products are already checked in, so 
there's no real reason to run it!

I make no statement as to the suitability of fastjsonschema and jsonlint 
for any uses that you might have.   Do your own research!

Note:  Thanks to Roy and Don for creating a great product in X3DUOM, 
upon which this is dependent upon.

Enjoy!

John

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