Based on MaybeFilter (https://gist.github.com/cvogt/9193220), it uses implicit class to add the methods to the Query objects. FilteredBy works for filtering lists and it returns the query if no filters were applied. FoundBy works for finding a single register, if no filter defined it returns None.

OptionFilter.scala

implicit class OptionFilter[ X, Y ]( query: Query[ X, Y, Seq ] ) {
  def filteredBy[ T ]( op: Option[ T ] )( f: ( X, T ) => Column[ Option[ Boolean ] ] ): Query[ X, Y, Seq ] = {
    op map { o => query.filter( f( _, o ) ) } getOrElse { query }
  }

  def foundBy[ T ]( op: Option[ T ] )( f: ( X, T ) => Column[ Option[ Boolean ] ] ): Query[ X, Y, Seq ] = {
    op map { o => query.filter( f( _, o ) ) } getOrElse { query.take( 0 ) }
  }
}

Do you know is this will work with Slick 3.x and do you have any example of putting it into practice?

Yes, I have been using it but I have made some changes to it. If you are still interested I can share it with you

Here is the new one: https://gist.github.com/leandrob13/a50f61db5a81d36dd5d35820fd9ca67e
I promise I will show you how to use it.

Here you go, a full example in slick 3.1: https://medium.com/pragmatic-scala/filter-ops-with-slick-3-1-1b0c4ec59bb1#.vb2kipa2a