Grails projection on arithmetic expression with executeQuery()?

Question

I need to get a sum of all items sold per order per store. I am running a sum() on expression using executeQuery(). It works fine as shown below but I wanted to know if ther

Answer 1

There are two options you can go with.

Option 1

You can add a formula mapping to your domain class then query it directly.

OrderItem {
  BigDecimal soldPrice
  Integer soldQuantity
  BigDecimal totalPrice

  static mapping = {
    totalPrice formula: "sold_price * sold_quantity"
  }

  static belongsTo = [order: Order, item: Item]

}

Now your criteria query can just contain

projections {
    sum("totalPrice")
}

Not only that but you can query it with dynamic finders OrderItem.findAllByTotalPriceGreaterThan(20.00) as well as simple access println "The final price is ${orderInstance.totalPrice}. We find this really nifty however there are times when you would want to get totalPrice before the OrderItem has been persisted so we usually write a simple(Not DRY) getter

BigDecimal getTotalPrice() {
    totalPrice ?: (soldPrice && soldQuantity) ? soldPrice * soldQuantity : null
}

But you only need this sort of thing if you require totalPrice before it has been persisted.

Option 2

Before formula mappings we used to drop down to the Hibernate Criteria API and use a sqlProjection Projection as part of our criteria query.

projections {
    addProjectionToList(Projections.sqlProjection(
            "sum(sold_price * sold_quantity) as totalPrice",
            ["totalPrice"] as String[], 
            [Hibernate.LONG] as Type[],
        ), "sumProjection")
 }

Note

I think it is important to note that in both the formula and the sql projection, use the column names in the database and your database specific sum syntax.