feat(core)!: Change data processing for multi-input-nodes (#4238)

Co-authored-by: कारतोफ्फेलस्क्रिप्ट™ <aditya@netroy.in>

packages/workflow/src/Expression.ts

@@ -358,8 +358,8 @@ export class Expression {
 		timezone: string,
 		additionalKeys: IWorkflowDataProxyAdditionalKeys,
 		executeData?: IExecuteData,
-		defaultValue?: boolean | number | string,
-	): boolean | number | string | undefined {
+		defaultValue?: boolean | number | string | unknown[],
+	): boolean | number | string | undefined | unknown[] {
 		if (parameterValue === undefined) {
 			// Value is not set so return the default
 			return defaultValue;

packages/workflow/src/Interfaces.ts

@@ -1429,6 +1429,8 @@ export interface INodeTypeDescription extends INodeTypeBaseDescription {
 	eventTriggerDescription?: string;
 	activationMessage?: string;
 	inputs: string[];
+	forceInputNodeExecution?: string | boolean; // TODO: This option should be deprecated after a while
+	requiredInputs?: string | number[] | number;
 	inputNames?: string[];
 	outputs: string[];
 	outputNames?: string[];

packages/workflow/src/Workflow.ts

@@ -1186,11 +1186,35 @@ export class Workflow {
 			// because then it is a trigger node. As they only pass data through and so the input-data
 			// becomes output-data it has to be possible.
 
-			if (inputData.hasOwnProperty('main') && inputData.main.length > 0) {
+			if (inputData.main?.length > 0) {
 				// We always use the data of main input and the first input for execute
 				connectionInputData = inputData.main[0] as INodeExecutionData[];
 			}
 
+			let forceInputNodeExecution = nodeType.description.forceInputNodeExecution;
+			if (forceInputNodeExecution !== undefined) {
+				if (typeof forceInputNodeExecution === 'string') {
+					forceInputNodeExecution = !!this.expression.getSimpleParameterValue(
+						node,
+						forceInputNodeExecution,
+						mode,
+						additionalData.timezone,
+						{ $version: node.typeVersion },
+					);
+				}
+
+				if (!forceInputNodeExecution) {
+					// If the nodes do not get force executed data of some inputs may be missing
+					// for that reason do we use the data of the first one that contains any
+					for (const mainData of inputData.main) {
+						if (mainData?.length) {
+							connectionInputData = mainData;
+							break;
+						}
+					}
+				}
+			}
+
 			if (connectionInputData.length === 0) {
 				// No data for node so return
 				return { data: undefined };