Slick 3.0 - 更新表中的列并返回整个表对象? [英] Slick 3.0 - Update columns in a table and return whole table object?

问题描述

这是 Slick 2 的实现.

Here is the implementation for Slick 2.

Slick 2 - 更新列在一个表中并返回整个表对象

有人知道如何在 Slick 3 中实现这一点吗?

Does anyone have ideas about how to implement this in Slick 3?

推荐答案

我能够通过扩展 Tim Harper 在 https://stackoverflow.com/a/28148606/310275

I was able to make this work by extending the awesome work by Tim Harper in https://stackoverflow.com/a/28148606/310275

这是我现在所做的:

package utils

import scala.language.existentials

import slick.ast._
import slick.driver.PostgresDriver._
import slick.driver.PostgresDriver.api._
import slick.jdbc.{GetResult, JdbcResultConverterDomain, SetParameter, StaticQuery ⇒ Q, StaticQueryInvoker, StreamingInvokerAction}
import slick.profile.SqlStreamingAction
import slick.relational.{CompiledMapping, ResultConverter}
import slick.util.SQLBuilder

object Slick {
  object UpdateReturning {
    implicit class UpdateReturningInvoker[E, U, C[_]](updateQuery: Query[E, U, C]) {


      def updateReturning[A, F](returningQuery: Query[A, F, C], v: U)(implicit db: Database) = {
        val ResultSetMapping(_,
          CompiledStatement(_, sres: SQLBuilder.Result, _),
          CompiledMapping(_updateConverter, _)) = updateCompiler.run(updateQuery.toNode).tree

        val returningNode = returningQuery.toNode
        val fieldNames = returningNode match {
          case Bind(_, _, Pure(Select(_, col), _)) =>
            List(col.name)
          case Bind(_, _, Pure(ProductNode(children), _)) =>
            children.map { case Select(_, col) => col.name }.toList
          case Bind(_, TableExpansion(_, _, TypeMapping(ProductNode(children), _, _)), Pure(Ref(_), _)) =>
            children.map { case Select(_, col) => col.name }.toList
        }

        implicit val pconv: SetParameter[U] = {
          val ResultSetMapping(_, compiled, CompiledMapping(_converter, _)) = updateCompiler.run(updateQuery.toNode).tree
          val converter = _converter.asInstanceOf[ResultConverter[JdbcResultConverterDomain, U]]
          SetParameter[U] { (value, params) =>
            converter.set(value, params.ps)
          }
        }

        implicit val rconv: GetResult[F] = {
          val ResultSetMapping(_, compiled, CompiledMapping(_converter, _)) = queryCompiler.run(returningNode).tree
          val converter = _converter.asInstanceOf[ResultConverter[JdbcResultConverterDomain, F]]
          GetResult[F] { p => converter.read(p.rs) }
        }

        val fieldsExp = fieldNames.map(quoteIdentifier).mkString(", ")
        val pconvUnit = pconv.applied(v)
        val sql = sres.sql + s" RETURNING ${fieldsExp}"
        val unboundQuery = Q.query[U, F](sql)
        val boundQuery = unboundQuery(v)

        new StreamingInvokerAction[Vector[F], F, Effect] {
          def statements = List(boundQuery.getStatement)
          protected[this] def createInvoker(statements: Iterable[String]) = new StaticQueryInvoker[Unit, F](statements.head, pconvUnit, (), rconv)
          protected[this] def createBuilder = Vector.newBuilder[F]
        }.asInstanceOf[SqlStreamingAction[Vector[F], F, Effect]]
      }
    }
  }

}

它需要他的代码然后将 StaticQuery 转换为 SqlStreamingAction

It takes his code then transforms the StaticQuery into a SqlStreamingAction

import utils.Slick.UpdateReturning._

val update = Users.filter(_.id === 1).map(_.firstName).
updateReturning(Users.map(_.firstName), ("Jane"))

val firstName = db.run(update.headOption).futureValue.get
firstName must === ("Jane")

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