Datamodel-code-generator: Add JSON Schema Parser

[koxudaxi]

The code generator should handle json schema.
The way is to implement JSON Shema Parser.

[prostomarkeloff]

Hello! Any updates now?

[koxudaxi]

Thank you for your comment.

Sorry, I'm developing my other projects now. [[local-data-api](https://github.com/koxudaxi/local-data-api), [py-data-api](https://github.com/koxudaxi/py-data-api)]

However, This project is active. I'm going to develop the project this week again.
Also, I'm waiting to publish pydantic version 1 to use Field().

If you want to support JSON schema then, I change a priority of this issue to high.

[prostomarkeloff]

Thanks for answer! I`m interesting in this project, i found it when search an any information about json schema parsers and code generators for pydantic. I will try to learn codebase and work about json schema parser.

[koxudaxi]

I guess the work may not hard, because of Json Schema, similar to OpenAPI.
I'm worried that this code is complex... I refactored the code. I feel the code is better than before refactoring :)

[prostomarkeloff]

Firstly, i think about $ref fields, without it, it is easy. I checked readme and saw information what $ref supported only in 1 file, we should to "fix" that😊

[joshbode]

I'm using https://github.com/wework/json-schema-to-openapi-schema and I haven't had any issues yet, though I'm probably not using all the features of JSON Schema. I use this script to run it from the command line:

#! /usr/bin/env node

const fs = require('fs');
const minimist = require('minimist');
const path = require('path');
const toOpenApi = require('json-schema-to-openapi-schema');
const yaml = require('js-yaml');


function main(args) {
  var argv = minimist(args);

  try {
    var json_schema = JSON.parse(fs.readFileSync(path.resolve(argv.input)));
  }
  catch (e) {
    console.log(e);
    return 1;
  }
  console.log(`JSON Schema read from ${argv.input}`);

  const openapi = toOpenApi(json_schema);

  try {
    fs.writeFileSync(path.resolve(argv.output), yaml.dump(openapi));
  }
  catch (e) {
    console.log(e);
    return 1;
  }
  console.log(`OpenAPI written to ${argv.output}`);
  return 0;
}

process.exit(main(process.argv.slice(2)));

usage:

$ json-schema-to-openapi --input schema.json --output openapi.yaml

I haven't gotten around to submitting it yet :)

[prostomarkeloff]

Sry me, i was very busy in this week. I plan start work about it tomorrow.

[koxudaxi]

I implemented the feature.
And I have released the version as 0.3.0
https://github.com/koxudaxi/datamodel-code-generator/pull/89