Class Transformer Class to BigQuery Schema

bigquery.ts

import { TableSchema } from '@google-cloud/bigquery';
import { TransformationType } from 'class-transformer';
import { defaultMetadataStorage } from 'class-transformer/cjs/storage';
import { MetadataStorage } from 'class-transformer/types/MetadataStorage';
import { Enum } from './autoenum';
import { ClassType } from './typeorm/class-type';
const meta: MetadataStorage = defaultMetadataStorage;

const BigQueryTypes = Enum(
  'STRING',
  'BYTES',
  'INTEGER',
  'FLOAT',
  'BOOLEAN',
  'TIMESTAMP',
  'DATE',
  'TIME',
  'DATETIME',
  'STRUCT',
);

export function classToBigQuerySchema<T>(clazz: ClassType<T>) {
  const schema: (NonNullable<TableSchema['fields']>[0] & {
    type: keyof typeof BigQueryTypes;
  })[] = [];
  // [
  //     {name: 'Name', type: 'STRING', mode: 'REQUIRED'},
  //     {name: 'Age', type: 'INTEGER'},
  //     {name: 'Weight', type: 'FLOAT'},
  //     {name: 'IsMagic', type: 'BOOLEAN'},
  //   ]

  const props = meta.getExposedProperties(
    clazz,
    TransformationType.CLASS_TO_CLASS,
  );

  for (const prop of props) {
    const type = Reflect.getOwnMetadata('design:type', clazz.prototype, prop);

    schema.push({
      name: prop,
      type:
        type === String
          ? 'STRING'
          : type === Number
          ? 'FLOAT'
          : type === Date
          ? 'DATETIME'
          : type === Boolean
          ? 'BOOLEAN'
          : type === BigInt
          ? 'INTEGER'
          : 'STRING',
    });
  }

  return schema;
}