將 Scala Slick 與數據庫枚舉一起使用

Question

使用 Slick 3 和 PostgreSQL，我需要查詢和更新具有枚舉類型列的表：

create type WeekDay as ENUM('sun','mon','tue','wed','thu','fri','sat');

create table shifts(
    id serial PRIMARY KEY,
    user_id INTEGER,
    branch_id INTEGER,
    start INTEGER,
    duration INTEGER,
    day WeekDay
    -- foreign keys etc.
);

我嘗試使用 Slick 的MappedColumnType[java.time.DayOfWeek,String] ，但這不能滿足 Postgres 的類型檢查器（TBH，理所當然）：

org.postgresql.util.PSQLException: ERROR: column "day" is of type weekday but expression is of type character varying
  Hint: You will need to rewrite or cast the expression.
  Position: 92
    at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2412)
    at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:2125)
    at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:297)
    at org.postgresql.jdbc.PgStatement.executeInternal(PgStatement.java:428)
    at org.postgresql.jdbc.PgStatement.execute(PgStatement.java:354)
    at org.postgresql.jdbc.PgPreparedStatement.executeWithFlags(PgPreparedStatement.java:169)
    at org.postgresql.jdbc.PgPreparedStatement.executeUpdate(PgPreparedStatement.java:136)
    at com.zaxxer.hikari.pool.ProxyPreparedStatement.executeUpdate(ProxyPreparedStatement.java:61)
    at com.zaxxer.hikari.pool.HikariProxyPreparedStatement.executeUpdate(HikariProxyPreparedStatement.java)
    at slick.jdbc.JdbcActionComponent$InsertActionComposerImpl$SingleInsertAction.$anonfun$run$15(JdbcActionComponent.scala:520)

表類：

class ShiftTable(tag:Tag) extends Table[Shift](tag, "shifts") {
  import Mappers.dayOfWeekMapper
  def id = column[Long]("id", O.AutoInc, O.PrimaryKey)
  def userId = column[Long]("user_id")
  def branchId = column[Long]("branch_id")
  def start = column[Int]("start")
  def duration = column[Int]("duration")
  def day = column[DayOfWeek]("day")    // <- problematic column

  // keys etc/
  def * = (id, userId, branchId, start, duration, day) <> (Shift.tupled, Shift.unapply)
}

如何將 Scala 值映射到自定義 PostgreSQL 類型？

Answer 1

看起來您可以使用沒有 pg-slick 的 String 映射到枚舉。

訣竅是向數據庫添加強制轉換，如PG JDBC 問題 1420 中所述：

CREATE CAST (character varying AS WeekDay) WITH INOUT AS ASSIGNMENT

CAST的文檔描述了WITH INOUT （避免編寫用於轉換的函數）和AS ASSIGNMENT （在分配值時隱式應用轉換）。

然后，您可以使用MappedColumnType.base[java.time.DayOfWeek, String]來定義從列到DayOfWeek的映射。

我在這里放置了一個可運行的示例： https : //github.com/d6y/pg-enum/blob/master/src/main/scala/main.scala