Slick: Option column filtering

问题

I want to do something like this (this is a made-up example to simplify my actual problem):

def findByGender(isMale: Option[Boolean]) = {
  People.filter(row => row.name.isNotNull && isMale match {
    case Some(true) => row.wife.isNotNull      // find rows where wife column is not null
    case Some(false) => row.wife.isNull        // find rows where wife column is null
    case None => true                          // select everything
  })    
}

This does not compile because of the last "true". Any better way to do this?

回答1:

You have to make it a Column[Boolean]:

def findByGender(isMale: Option[Boolean]) = {
  People.filter(row => row.name.isNotNull && isMale match {
    case Some(true) => row.wife.isNotNull      // find rows where wife column is not null
    case Some(false) => row.wife.isNull        // find rows where wife column is null
    case None => LiteralColumn(true)           // select everything
  })    
}

回答2:

If you're using Slick 3.3.x you can use the following solution:

def findByGender(isMale: Option[Boolean]) = 
  People
    .filter(_.name.isDefined)
    .filterIf(isMale == Some(true))(_.wife.isDefined)
    .filterIf(isMale == Some(false))(_.wife.isEmpty)

or

def findByGender(isMale: Option[Boolean]) = 
  People
    .filter(_.name.isDefined)
    .filterOpt(isMale) {
      case (row, true) => row.wife.isDefined
      case (row, false) => row.wife.isEmpty
    }

There are 3 cases:

1. isMale is defined and equal Some(true)

   Result SQL: select * from people when (name is not null) and (wife is not null);

2. isMale is defined and equal Some(false):

   Result SQL: select * from people when (name is not null) and (wife is null);

3. isMale is empty

   Result SQL: select * from people when name is not null;

来源：https://stackoverflow.com/questions/26554224/slick-option-column-filtering