Enhance Avro to support data validation via Regular Expression

avro-validation.js

/*
 * Enhance Avro to support data validation via Regular Expression
 */
const avro = require('avsc')

class ValidatedString extends avro.types.LogicalType {
  constructor (attrs, opts) {
    super(attrs, opts)
    this._pattern = new RegExp(attrs.pattern)
  }

  _toValue (val) {
    if (!this._pattern.test(val)) {
      throw new Error('invalid string: ' + val)
    }
    return val
  }
}

const type = avro.parse({
  name: 'Example',
  type: 'record',
  fields: [
    {
      name: 'custId',
      type: 'string'   // Normal (free-form) string.
    },
    {
      name: 'sessionId',
      type: {
        type: 'string',
        logicalType: 'validated-string',
        pattern: '^[0-9]{4}-[0-9]{2}$' // Validation pattern.
      }
    },
  ]
}, {logicalTypes: {'validated-string': ValidatedString}})

// tests
console.log(type.isValid({custId: 'abc', sessionId: '1234-12'})) // true
console.log(type.isValid({custId: 'abc', sessionId: 'foobar'}))  // false