scala slick or 和查询

Question

我的问题可能听起来很平淡，但我仍然没有解决它。

我的 Products Table 实现如下

class ProductsTable(tag: Tag) extends Table[Product](tag, "PRODUCTS") {
  def id = column[Int]("PRODUCT_ID", O.PrimaryKey, O.AutoInc)
  def title = column[String]("NAME")
  def description = column[String]("DESCRIPTION")
  def style = column[String]("STYLE")
  def price = column[Int]("PRICE")
  def category_id = column[Int]("CATEGORY_ID")
  def size_id = column[Int]("SIZE_ID")
  def brand_id = column[Int]("BRAND_ID")

  def * = (id.?, title, description, style, price, category_id, size_id, brand_id) <>(Product.tupled, Product.unapply _)
}

及其在

中的表示

val Products = TableQuery[ProductsTable]

如何实现与 SQl 查询等效的查询：

select * from products where( category_id = 1 or category_id = 2 or category_id = 3 ) and (price between min and max)

Answer 1

试试这样的：

val query = Products filter { p => (p.category_id inSet List(1,2,3)) && p.price > min && p.price < max }
val result = db.run(query.result)

您可以使用println(query.result.statements) 查看查询的样子。

编辑：

回答其他问题。您可以为您的查询创建一个接受可选最小值和最大值的函数：

def getProductsQuery(maybeMin: Option[Int] = None, maybeMax: Option[Int] = None) = {
  val initialQuery = val query = Products filter { p => (p.category_id inSet List(1,2,3)) }
  val queryWithMin = maybeMin match {
    case Some(min) => initialQuery filter { _.price > min }
    case None => initialQuery
  }
  val queryWithMax = maybeMax match {
    case Some(max) => queryWithMin filter { _.price < max }
    case None => queryWithMin 
  }
  queryWithMax
}

然后您可以执行以下任何操作：

val q1 = getProductsQuery() // without min or max
val q2 = getProductsQuery(maybeMin = Option(3)) // only min
val q3 = getProductsQuery(maybeMax = Option(10)) // only max
val q4 = getProductsQuery(maybeMin = Option(3), maybeMax = Option(10)) // both

并根据需要运行其中任何一个...