nestjs swagger helper for extracting inline schemas to the document schemas

hack.ts

/* eslint-disable @typescript-eslint/no-explicit-any */

import { getSchemaPath, OpenAPIObject } from '@nestjs/swagger';
import _set from 'lodash.set';
import _get from 'lodash.get';

function flattenObject(theObject: any): Record<string, any> {
  const toReturn: any = {};

  for (const objectKey in theObject) {
    if (!Object.prototype.hasOwnProperty.call(theObject, objectKey)) {
      continue;
    }

    if (typeof theObject[objectKey] == 'object') {
      const flatObject = flattenObject(theObject[objectKey] as any);
      for (const x in flatObject) {
        if (!Object.prototype.hasOwnProperty.call(flatObject, x)) {
          continue;
        }

        toReturn[objectKey + '.' + x] = flatObject[x];
      }
    } else {
      toReturn[objectKey] = theObject[objectKey];
    }
  }

  return toReturn;
}

/**
 * # What is this?
 *
 * The plugin goes over endpoint definitions, looks for responses that are titles `PaginatedResponseOf(.*)`,
 * And moves them to the global schemas section of the document, replacing the response scheme to reference them.
 *
 * # Why is it needed?
 *
 * 1. Without that, you don't get an accurate schema definition in the definitions section,
 *    Which is bad for user experience
 * 2. And this is the bad one, openapi-generator-cli with the typescript-fetch template generates broken code,
 *    Because it does not take the `title` of the inline schema as the name of the schema.
 *    Example code: `PaginationResponseDTO & objectFromJson(value)` instead of `PaginatedResponseOfMyModelFromJson(value)`
 */
export function extractPaginatedResponsesToDefinitions(document: OpenAPIObject): void {
  const flattenedSwagger = flattenObject(document);
  const keys = Object.keys(flattenedSwagger);

  keys
    .filter(k => k.endsWith('schema.title'))
    .forEach(key => {
      const title = flattenedSwagger[key];
      if (!title.startsWith('PaginatedResponseOf')) {
        return;
      }

      const schemaKey = key.replace('.title', '');
      const schema = _get(document, schemaKey);

      _set(document, schemaKey, {
        $ref: getSchemaPath(title),
      });

      document.components.schemas[title] = schema;
    });
}

A workaround was found, so this is here for backup and documentation of hardships of the process