Using Generic with a nested case class

[Brendan]

Hi,

I'm trying to convert an HList to a case class with a nested case class within it

I can see that using Generic is only converting the case class to an HList at the top level 

Is there a simple to way to achieve this?

Thanks

Brendan

scala> import shapeless._

import shapeless._

scala> case class Address(street : String, city : String, postcode : String)

defined class Address

scala> case class Person(name : String, age : Int, address : Address)

defined class Person

scala> val personGen = Generic[Person]

personGen: shapeless.Generic[Person]{type Repr = shapeless.::[String,shapeless.::[Int,shapeless.::[Address,shapeless.HNil]]]} = $1$$1@4ac8cdf4

scala> val personHList = "tom" :: 10 :: "downing st" :: "london" :: "sw1" :: HNil

personHList: shapeless.::[String,shapeless.::[Int,shapeless.::[String,shapeless.::[String,shapeless.::[String,shapeless.HNil]]]]] = tom :: 10 :: downing st :: london :: sw1 :: HNil

scala> val person = personGen.from(personHList)

<console>:16: error: type mismatch;

 found   : shapeless.::[String,shapeless.::[Int,shapeless.::[String,shapeless.::[String,shapeless.::[String,shapeless.HNil]]]]]

 required: personGen.Repr

    (which expands to)  shapeless.::[String,shapeless.::[Int,shapeless.::[Address,shapeless.HNil]]]

       val person = personGen.from(personHList)

[Miles Sabin]

On Fri, Feb 14, 2014 at 12:02 PM, Brendan <brendan....@gmail.com> wrote:
> I'm trying to convert an HList to a case class with a nested case class
> within it I can see that using Generic is only converting the case class to an HList
> at the top level

Yes, that's right, Generic is designed for traversing/transforming one
layer at a time.

> Is there a simple to way to achieve this?

What is it exactly that you want to do? The everything and everywhere
combinators traverse/transform across multiple layers: you can find a
couple of examples here,

https://github.com/milessabin/shapeless/blob/master/examples/src/main/scala/shapeless/examples/sybclass.scala

Cheers,


Miles

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Miles Sabin
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[brendan....@gmail.com]

I was attempting to be able to take a flat tuple of values and convert it into an arbitrarily nested case class. 

It was specifically going to used to transform a java.sql.ResultSet into any case class (which may contain other case classes)

We ended up being able to implement it in a different way

Thanks for your help

Brendan

[Владимир Морозов]

Hi,

I try to solve similar problem, could you share information about how you map ResultSet to nested case classes ?

пятница, 25 апреля 2014 г., 17:40:43 UTC+3 пользователь Brendan Maginnis написал:

[Antonio Fijo]

Hi all,
I guess this is what is wanted:

case class Address(street : String, city : String, postcode : String)

case class Person(name : String, age : Int, address : Address)

val addressGen = Generic[Address]

val personGen = Generic[Person]

val addressHList = "downing st" :: "london" :: "sw1" :: HNil
val address = addressGen.from(addressHList)

val personHList = "tom" :: 10 :: address :: HNil
val person = personGen.from(personHList)

println(person) // Person(tom,10,Address(downing st,london,sw1))

[Miles Sabin]

Hi folks,

This is a reminder that this mailing list is deprecated. Q&A on this
sort is probably best handled on StackOverflow. More general
discussion belongs on the shapeless gitter channel,

https://gitter.im/milessabin/shapeless

Cheers,


Miles

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