Functions

openVALIDATION provides various functions. Let's say we want to check in a rule whether we have spent more money on shopping than our budget allows.

We have the following scheme:

YAML

shopping_list: 
    - article : text
      price : 0

JSON

{
	shopping_list: [
		{
			article : "text",
			price : 0
		}
	]
}

And here's the rule that goes with it:

SUM OF shopping_list.price
    AS expenses

the expenses MUST NOT EXCEED the budget of 20 €.

First, we define a variable called Expenses. This variable uses the SUM OF function. The list of all prices from the shopping list is transferred to the function. The function SUM OF calculates a sum and thus has a return value of type Number. The Issues variable is automatically assigned this data type and can then be used within the rule.

The rule itself contains a numeric comparison operation. The whole thing looks like this:

var expenses = sum(shopping_list.map(a -> a.price))

If (expenses > 20 )
   throw Error("the expenses MUST NOT EXCEED the budget of 20 €")

Functions can of course also be used within a rule.