在Scala对象中按字符串格式按日期排序

Question

I have Following Object structure in scala (case classes) :

{
    "accounts": [{
        "accountManagement": {

            "accountStatus": "submitted",
            "accountManagementId": "1513684862218",
            "submittedDate": "19/12/2017"

        }
    }]
}

Look at List "accounts". I want to sort this list on the basis of field "submittedDate" from "accountManagement". Note that submitted date is in string format.

I tried this but not working.

for (accountManagement: AccountManagement <- accountManagementList) {
        try {

          if(accountManagement.submittedDate != null && accountManagement.submittedDate.nonEmpty){

            accountManagement.submittedDate = dateFormatter.parse(accountManagement.submittedDate)
          }

        }catch {
          case e:Exception =>
        }

        accountManagementsNew = accountManagementsNew ::: List(accountManagement)
      }

      accountManagementsNew.sortBy(_.updatedDate.getTime)

Answer 1

Lets say your case class looked like this.

// Note that in scala its preferred to use Option to indicate nullable fields
case class AccountManagement(accountStatus: String,
                             accountManagementId: Long,
                             submittedDate: Option[String])

val accounts = List(
  AccountManagement("submitted", 1L, Some("21/12/2017")),
  AccountManagement("submitted", 2L, Some("19/12/2017")),
  AccountManagement("submitted", 3L, None),
  AccountManagement("submitted", 4L, Some("20/12/2017"))
)

val dtf = DateTimeFormatter.ofPattern("dd/MM/yyyy")

You can either define an implicit ordering that you want to use in this context

implicit val localDateOrdering: Ordering[LocalDate] = Ordering.by(_.toEpochDay)

accounts.filterNot(_.submittedDate.isEmpty) sortBy {
  case AccountManagement(_, _, Some(submittedDateString)) => LocalDate.parse(submittedDateString, dtf)
}

or you can directly specify that you would like to use the millisecond representation of said date to sort your data set

accounts.filterNot(_.submittedDate.isEmpty) sortBy {
  case AccountManagement(_, _, Some(submittedDateString)) => LocalDate.parse(submittedDateString, dtf).toEpochDay
}

Answer 2

If I understand your requirement correctly, you can first assemble a list of AccountManagementNew from AccountManagement by converting the String-type date to LocalDate , then perform the sorting by date as shown below. Note that Try is used to handle Success/Failure cases.

import java.time.LocalDate
import java.time.format.DateTimeFormatter
import scala.util.{Try, Success, Failure}

case class AccountManagement(
  accountStatus: String, accountManagementId: String, submittedDate: String
)
case class AccountManagementNew(
  accountStatus: String, accountManagementId: String, updatedDate: LocalDate
)

val accountManagementList = List[AccountManagement](
  AccountManagement("submitted", "1513684862218", "19/12/2017"),
  AccountManagement("submitted", "1513684862219", "09/01/2018"),
  AccountManagement("submitted", "1513684862220", "29/11/2017")
)

val datePattern = DateTimeFormatter.ofPattern("dd/MM/yyyy")

// Assemble a list of the AccountManagementNew case class
val amNewList =
  for (am <- accountManagementList) yield {
    Try( LocalDate.parse(am.submittedDate, datePattern) ) match {
      case Success(d) =>
        AccountManagementNew(am.accountStatus, am.accountManagementId, d)
      case Failure(_) =>
        AccountManagementNew(am.accountStatus, am.accountManagementId, LocalDate.MIN)
    }
  }

// Use `LocalDate.toEpochDay` for date ordering
implicit val dateOrdering = Ordering.by{d: LocalDate => d.toEpochDay}

amNewList.sortBy(_.updatedDate)
// res1: List[AccountManagementNew] = List(
//   AccountManagementNew(submitted,1513684862220,2017-11-29),
//   AccountManagementNew(submitted,1513684862218,2017-12-19),
//   AccountManagementNew(submitted,1513684862219,2018-01-09)
// )