[Get Familiar] Add schema validation for template configuration

[Udayraj123]

Right now, OMRChecker does not handle invalid template.json files. It simply tries to process the file and throws an errors.

We want to extend that an do a json schema validation for the file.

Steps:

1. Study current structure of the Template file
2. Create a json schema for the same.
3. Use python-jsonschema or similar library to throw validation errors when the input file doesn't match with the schema.

Resources:

1. https://python-jsonschema.readthedocs.io/en/stable/
2. https://github.com/python-jsonschema/jsonschema
3. https://github.com/Udayraj123/OMRChecker/wiki/About-Templates
4. https://github.com/Udayraj123/OMRChecker/wiki/User-Guide

Note: this issue is marked with the hacktoberfest label. Follow #hacktoberfest-discussions on Discord for further details .

[SpyzzVVarun]

Hi @Udayraj123 , should the schema be created exactly for the template file mentioned here: Template File ?

[Udayraj123]

That's correct. The same schema can also be found for all template.json files in samples folder

[SpyzzVVarun]

Would it be possible to get an example of an incorrect template file, I did write some code for the validation schema and error handling, but I'm not sure about the constraints to be put in my schema. Also, when I tried setting the dimensions in the sample template to 3, I expected an error but the code seemed to run fine. So, it would be helpful to know the expected constraints.

[Udayraj123]

You can create incorrect template.json files by removing some of the mandatory keys, or changing their camelCase to TitleCase for keys(in which case validation error should mention that).
Setting 3rd dimension worked as code can run fine because it is written gracefully. Still we need the validation error to be thrown as a caution for future changes.

[SpyzzVVarun]

Have generated a draft PR, do let me know if this is what you were expecting.

[Udayraj123]

@SpyzzVVarun discussed on discord. Let me know once all changes done..

[Udayraj123]

Merged #60

[Udayraj123]

extended in #65