vertx / io.vertx.reactivex.ext.web.api.validation / ParameterValidationRule / allowEmptyValue

# allowEmptyValue

`open fun allowEmptyValue(): Boolean`

allowEmptyValue is used in query, header, cookie and form parameters. This is its behaviour:

1. During validation, the ValidationHandler check if there's a parameter with combination of location and name as defined in this rule
2. If it not exists, It will check allowEmptyValue and if there's a default value set inside ParameterTypeValidator:

- If this condition it's true, It marks as validated the parameter and returns the default value (inside RequestParameter)
- If this condition it's false, It throws ValidationException

3. If the parameter exists, It checks if parameter is null or empty string:

- If allowEmptyValue it's true, It marks as validated the parameter and returns the default value if it exists (inside RequestParameter)
- If allowEmptyValue it's false, It throws ValidationException

Return
value of allowEmptyValue