Any ideas how to create a `data class` using param...

# announcements

[guppyfaced]

Any ideas how to create a data class using parameters? I'm thinking of doing it with a map of values, but if there's a constructor method I could call, that would be great.

[diesieben07]

Can you clarify what you mean by "using parameters"? Do you mean you have a map of name to parameter value?

[guppyfaced]

That's right, a map of names and types.

[diesieben07]

data class Person(val name: String, val age: Int)

fun main() {
    val args = mapOf("name" to "Peter", "age" to 23)
    val constructor = Person::class.primaryConstructor!!
    val person = constructor.callBy(
        constructor.parameters.associateWith { args[it.name] }
    )
    println(person)
}

[diesieben07]

Note that this requires kotlin-reflect

[guppyfaced]

I haven't used the kotlin-reflect features in depth, apart from the ::class function. Do I have to import an addition kotlin-reflect feature? I can't get this code to run..

[diesieben07]

What error do you get?

[guppyfaced]

unresolved reference: primaryConstructor

[diesieben07]

Yes, you need to have kotlin-reflect on the classpath (compile 'org.jetbrains.kotlin:kotlin-reflect' when using Gradle).

[guppyfaced]

Ah, I'm installing it now...

[guppyfaced]

Another unresolved reference in line constructor.parameters.associateWith { args[it.name]

[guppyfaced]

associateWith does not exist

[diesieben07]

It was added in 1.3, you can use associate { it to args[it.name] } for 1.2.x instead

[guppyfaced]

That's works for me. I'll need to update my Kt version for future reference...

[snowe]

also if you are using the kotlin dsl you can shorten the kotlin-reflect declaration to just implementation(kotlin("reflect"))