I have a Scala case class
containing command-line configuration information:
case class Config(emailAddress: Option[String],
firstName: Option[String]
lastName: Option[String]
password: Option[String])
I am writing a validation function that checks that each of the values is a Some
:
def validateConfig(config: Config): Try[Config] = {
if (config.emailAddress.isEmpty) {
Failure(new IllegalArgumentException("Email Address")
} else if (config.firstName.isEmpty) {
Failure(new IllegalArgumentException("First Name")
} else if (config.lastName.isEmpty) {
Failure(new IllegalArgumentException("Last Name")
} else if (config.password.isEmpty) {
Failure(new IllegalArgumentException("Password")
} else {
Success(config)
}
}
but if I understand monads from Haskell, it seems that I should be able to chain the validations together (pseudo syntax):
def validateConfig(config: Config): Try[Config] = {
config.emailAddress.map(Success(config)).
getOrElse(Failure(new IllegalArgumentException("Email Address")) >>
config.firstName.map(Success(config)).
getOrElse(Failure(new IllegalArgumentException("First Name")) >>
config.lastName.map(Success(config)).
getOrElse(Failure(new IllegalArgumentException("Last Name")) >>
config.password.map(Success(config)).
getOrElse(Failure(new IllegalArgumentException("Password"))
}
If any of the config.XXX
expressions returns Failure
, the whole thing (validateConfig
) should fail, otherwise Success(config)
should be returned.
Is there some way to do this with Try
, or maybe some other class?
Here's a solution that I came up with after some searching and scaladocs reading:
Similar to Travis Brown's answer.