DatumExpression topic

This instructions asks a node to evaluate a datum expression and return the result.

DatumExpression exampleDatumExpression example (compact)

{
    "nodeId": 123,
    "topic": "DatumExpression",
    "parameters": [
        {
            "name": "expression",
            "value": "sum(latestMatching('/power/*').![watts * powerFactor])"
        }
    ]
}

{
    "nodeId": 123,
    "topic": "DatumExpression",
    "params": {
        "expression": "sum(latestMatching('/power/*').![watts * powerFactor])"
    }
}

Parameters

The following instruction parameters are available:

Parameter	Description
executionDate	A future execution date. See deferred instructions for more details.
expression	The id of the instruction to cancel.
lang	The ID of the expression language to use. See table below for possible values. If not provided then SpEL will be assumed.

Supported expression languages

The following lang parameter values are supported:

Language	ID
SpEL	net.solarnetwork.common.expr.spel.SpelExpressionService

Result

Once executed, a result result parameter will be provided with the expression result. For example:

DatumExpression example result

{
    "nodeId": 123,
    "topic": "DatumExpression",
    "statusDate": "2024-04-03 17:27:41.601474Z",
    "state": "Completed",
    "parameters": [
        {
            "name": "expression",
            "value": "sum(latestMatching('/power/*').![watts * powerFactor])"
        }
    ],
    "resultParameters": {
        "result": 12359.99964279
    }
}