Question

我正在对本质上具有许多字段的某些数据类型进行建模。

然后，我得到的是丑陋的代码，其中该类的构造函数具有一长列参数及其所有子类。

我有点怀疑 BuilderPattern 是否是一个好的解决方案。

例如，这是通用类Transaction：

class Transaction(
    source: String,
    format: String,
    id: String,
    amount: Double,
    currency: String,
    senderAccount: String,
    senderName: String,
    receiverAccount: String,
    receiverName: String,
    execDate: LocalSate,
    createdDateTime: Instant)

这是子类A TxTypeA，它具有一些特定于typeA的特殊字段：

class TxTypeA(
    source: String,
    format: String,
    id: String,
    amount: Double,
    currency: String,
    senderAccount: String,
    senderName: String,
    receiverAccount: String,
    receiverName: String,
    execDate: LocalSate,
    createdDateTime: Instant,
    typeAField1: String,
    typeAField2: String,
    typeAField3: String
) extends Transaction(
    source,
    format,
    id,
    amount,
    currency,
    senderAccount,
    senderName,
    receiverAccount,
    receiverName,
    execDate,
    createdDateTime)

这是子类B TxTypeB，它具有一些特定于typeB的特殊字段：

class TxTypeB(
    source: String,
    format: String,
    id: String,
    amount: Double,
    currency: String,
    senderAccount: String,
    senderName: String,
    receiverAccount: String,
    receiverName: String,
    execDate: LocalSate,
    createdDateTime: Instant,
    typeBField1: String,
    typeBField2: String,
    typeBField3: String,
    typeBField4: String,
    typeBField5: String,
    typeBField6: String,
    typeBField7: String
) extends Transaction(
    source,
    format,
    id,
    amount,
    currency,
    senderAccount,
    senderName,
    receiverAccount,
    receiverName,
    execDate,
    createdDateTime)

有人对此有更好的解决方案吗？

更新：

在我的项目中，我创建了另一个名为Party的类，该类包装了Account和Name，但这只是释放了痛苦，并未解决核心问题。 / p>

case class Party(account: String, name: String)

class Transaction(
    source: String,
    format: String,
    id: String,
    amount: Double,
    currency: String,
    senderParty: Party,
    receiverParty: Party,
    execDate: LocalSate,
    createdDateTime: Instant)

Answer 1

您可以通过使Transaction为特征来对此进行整理：

trait Transaction {
  val source: String
  val format: String
  val id: String
  val amount: Double
  val currency: String
  val senderAccount: String
  val senderName: String
  val receiverAccount: String
  val receiverName: String
  val execDate: LocalState
  val createdDateTime: Instant
}

case class TxTypeA(
  source: String,
  format: String,
  id: String,
  amount: Double,
  currency: String,
  senderAccount: String,
  senderName: String,
  receiverAccount: String,
  receiverName: String,
  execDate: LocalState,
  createdDateTime: Instant,
  typeAField1: String,
  typeAField2: String,
  typeAField3: String
) extends Transaction

case class TxTypeB(
  source: String,
  format: String,
  id: String,
  amount: Double,
  currency: String,
  senderAccount: String,
  senderName: String,
  receiverAccount: String,
  receiverName: String,
  execDate: LocalState,
  createdDateTime: Instant,
  typeBField1: String,
  typeBField2: String,
  typeBField3: String,
  typeBField4: String,
  typeBField5: String,
  typeBField6: String,
  typeBField7: String
) extends Transaction

如果需要，您甚至可以将这些值组合成包含相关字段的小写类，如下所示：

case class Party(account: String, name: String)

trait Transaction {
  val source: String
  val format: String
  val id: String
  val amount: Double
  val currency: String
  val sender: Party
  val receiver: Party
  val execDate: LocalState
  val createdDateTime: Instant
}

case class TxTypeA(
  source: String,
  format: String,
  id: String,
  amount: Double,
  currency: String,
  sender: Party,
  receiver: Party,
  execDate: LocalState,
  createdDateTime: Instant,
  typeAField1: String,
  typeAField2: String,
  typeAField3: String
) extends Transaction

case class TxTypeB(
  source: String,
  format: String,
  id: String,
  amount: Double,
  currency: String,
  sender: Party,
  receiver: Party,
  execDate: LocalState,
  createdDateTime: Instant,
  typeBField1: String,
  typeBField2: String,
  typeBField3: String,
  typeBField4: String,
  typeBField5: String,
  typeBField6: String,
  typeBField7: String
) extends Transaction

或者您可以走得更远，将Transaction作为参数传递而不是扩展它：

case class Party(account: String, name: String)

case class Transaction (
  val source: String,
  val format: String,
  val id: String,
  val amount: Double,
  val currency: String,
  val sender: Party,
  val receiver: Party,
  val execDate: LocalState,
  val createdDateTime: Instant
)

case class TxTypeA(
  transaction: Transaction,
  typeAField1: String,
  typeAField2: String,
  typeAField3: String
)

case class TxTypeB(
  transaction: Transaction,
  typeBField1: String,
  typeBField2: String,
  typeBField3: String,
  typeBField4: String,
  typeBField5: String,
  typeBField6: String,
  typeBField7: String
)

这取决于您的用例以及可行的方法。如果您正在执行格式化Json的操作，我建议您对其进行扩展，以使Json字段匹配（或创建特定的Reads等）。

Answer 2

为什么不使用案例类来建模相关信息？例如交易中的发送者和接收者可以建模为单独的案例类；

case class Account(id: String, name: String)


class Transaction(
    source: String,
    format: String,
    id: String,
    amount: Double,
    currency: String,
    sender: Account
    reciever: Account
    execDate: LocalSate,
    createdDateTime: Instant)

这样，您可以减少构造函数中的参数数量。然后，您可以将辅助方法添加到Transaction类或实现构建器模式，例如TransactionBuilder.withSender（senderName，senderAccountId）

Answer 3

在这种情况下，我希望将这些字段组合到其他类中。

例如，交易可以由发送者，接收者，金额等组成。

如何处理构造函数中的参数太多的类-Scala？

3 个答案: