Scala Play Forms：使用 HLists 绕过 22 个字段的限制

Question

Slick 使用 HList 的一种 hack 来管理超过 22 列的表，例如这个（自动生成的）行模型构造函数：

type SamplesRow = HCons[Int,HCons[String,HCons[Option[String],HCons[Int,HCons[String,HCons[Int,HCons[Int,HCons[Option[Int],HCons[Option[Float],HCons[Option[Float],HCons[Option[String],HCons[Option[String],HCons[Boolean,HCons[Option[String],HCons[Option[String],HCons[Option[String],HCons[Option[String],HCons[Option[String],HCons[Option[Int],HCons[Option[Float],HCons[Option[Float],HCons[Option[Float],HCons[Option[String],HCons[Option[String],HNil]]]]]]]]]]]]]]]]]]]]]]]]

def SamplesRow(id: Int, name: String, shortName: Option[String] = None, sampleTypeId: Int, receivedDate: String, projectId: Int, taxoId: Int, quantifMethodId: Option[Int] = None, concentration: Option[Float] = None, volume: Option[Float] = None, description: Option[String] = None, comment: Option[String] = None, istrashed: Boolean = false, commentCustomer: Option[String] = None, createdAt: Option[String] = None, updatedAt: Option[String] = None, createdBy: Option[String] = None, updatedBy: Option[String] = None, poId: Option[Int] = None, `260280Ratio`: Option[Float] = None, `260230Ratio`: Option[Float] = None, rin: Option[Float] = None, concUpdatedAt: Option[String] = None, concUpdatedBy: Option[String] = None): SamplesRow = {
  id :: name :: shortName :: sampleTypeId :: receivedDate :: projectId :: taxoId :: quantifMethodId :: concentration :: volume :: description :: comment :: istrashed :: commentCustomer :: createdAt :: updatedAt :: createdBy :: updatedBy :: poId :: `260280Ratio` :: `260230Ratio` :: rin :: concUpdatedAt :: concUpdatedBy :: HNil
}

我可以使用相同的技巧让一个表单保存 24 个值吗？喜欢

val tableForm: Form[SamplesRow] = Form(
  mapping(
    ID -> ignored(-1),
    NAME -> text,
    SHORT_NAME -> optional(text),
    SAMPLE_TYPE_ID -> number,
    RECEIVED_DATE -> default(text, NOW),
    PROJECT_ID -> number,
    TAXO_ID -> number,
    QUANTIF_METHOD_ID -> optional(number),
    CONCENTRATION -> optional(of[Float]),
    VOLUME -> optional(of[Float]),
    DESCRIPTION -> optional(text),
    COMMENT -> optional(text),
    IS_TRASHED -> default(boolean, false),
    COMMENT_CUSTOMER -> optional(text),
    CREATED_AT -> optional(text),
    UPDATED_AT -> optional(text),
    CREATED_BY -> optional(text),
    UPDATED_BY -> optional(text),
    PO_ID -> optional(number),
    RATIO_260_280 -> optional(of[Float]),
    RATIO_260_230 -> optional(of[Float]),
    RIN -> optional(of[Float]),
    CONC_UPDATED_AT -> optional(text),
    CONC_UPDATED_BY -> optional(text)
  )(SamplesRow)(???)
)

我觉得上面的构造函数 def SamplesRow 可以用作 apply 方法，但是我可以将什么用作“unapply”？

我知道我应该使用嵌套映射，但是我无法将结果直接映射到 Slick 行模型，而且编写 100 行代码来实现转换以便我可以执行插入听起来很愚蠢.

Answer 1

我很想完全摆脱 Forms 并用自定义 JsObject 解析替换它们：

// Controller Action:
val content = request.body.asJson
val row = rowFromJson(content)

// Somewhere else
import play.api.libs.json._
def rowFromJson(j: JsObject): SamplesRow = {
  SamplesRow(
    (j \ "id").as[Int],
    (j \ "name").as[String]
    ...
  )
}

其中 SamplesRow 是 Samples#TableElementType 的 table Samples <: AbstractTable[_]。

Scala Play Forms：使用 HLists 绕过 22 个字段的限制

Scala Play Forms: using HLists to get around the 22 fields limitation

scala

slick

playframework-2.5