Scala Slick: MappedColumnType cannot find implicit value for BaseColumlnType[String]

Question

I'm trying to set up database columns in Slick with non-primitive objects. I've spent the past day researching MappedColumnType for mapping custom objects to columns, and as far as I can tell I'm implementing them as people recommend. Unfortunately, the following code produces an error:

  implicit val localDateMapper = MappedColumnType.base[LocalDate, String]
    (
    //map date to String
    d => d.toString,
    //map String to date
    s => LocalDate.parse(s)
    )

And here is the error:

could not find implicit value for evidence parameter of type slick.driver.H2Driver.BaseColumnType[String]

I've seen multiple examples where people map custom objects to and from Strings. I figure there must be something I'm missing?

For reference, I'm using Play Slick 1.1.1 and Scala 2.11.6. The former supports Slick 3.1.

Answer 1

您可以使用以下命令导入BaseColumnType[String] ：

import slick.driver.H2Driver.api.stringColumnType