Utils / Controller / evaluateNodeProperty

Function: evaluateNodeProperty()

function evaluateNodeProperty(params): Promise<[Error | undefined, any]>;

Evaluates a node property in the Node-RED environment. This function wraps the evaluateNodeProperty utility from RED.util and returns a Promise. It resolves with a tuple containing an Error (if any) and the evaluation result.

The evaluation is performed asynchronously, and the function never rejects. The result will always be a tuple where:

• The first element is an Error if one occurs during the evaluation, or undefined if no error occurs.
• The second element is the result of the property evaluation, or undefined if no result is produced.

Note: This function is designed to be used in the context of Node-RED node development. It requires access to the RED object and the necessary node properties.

Parameters

Parameter	Type	Description
params	EvaluateNodePropertyParams	The parameters needed to evaluate the node property.

Returns

Promise<[Error | undefined, any]>

• A promise that resolves with a tuple containing:
• The error (if any) or undefined if no error occurs.
• The result of the evaluation or undefined if no result is produced.

Examples

// Example usage of evaluateNodeProperty with async/await
async function processNodeProperty() {
  const params: EvaluateNodePropertyParams = {
    value: "msg.payload",
    type: "jsonata",
    node: myNode,  // assuming myNode is a valid Node object
    msg: myMsg,    // assuming myMsg is a valid NodeMessage object
  };

  const [err, result] = await evaluateNodeProperty(params);

  if (err) {
    console.error("Error:", err);
  } else {
    console.log("Evaluation Result:", result);
  }
}

// Handling the result when using the promise directly
evaluateNodeProperty({
  value: "msg.payload.someProperty",
  type: "str",
  node: myNode,  // assuming myNode is a valid Node object
  msg: myMsg,    // assuming myMsg is a valid NodeMessage object
})
.then(([err, result]) => {
  if (err) {
    console.error("Error:", err);
  } else {
    console.log("Result:", result);
  }
});