{
  "name": "Null handling",
  "rules": [
    {
      "id": "flag-missing-email",
      "description": "IsNull / IsNotNull take no value. A missing dictionary key or a null along a path resolves to null.",
      "condition": { "field": "Customer.Email", "operator": "IsNull" },
      "actions": [ { "type": "setOutput", "target": "NeedsEmail", "value": true } ]
    },
    {
      "id": "safe-greeting",
      "description": "coalesce supplies a default when a field is null, so the message never says 'Hello, !'.",
      "condition": { "field": "Order.Total", "operator": "IsNotNull" },
      "actions": [
        {
          "type": "setOutput",
          "target": "Greeting",
          "value": {
            "op": "concat",
            "operands": [
              "Hello, ",
              { "op": "coalesce", "operands": [ { "field": "Customer.Name" }, "there" ] },
              "!"
            ]
          }
        }
      ]
    }
  ]
}