Pre Post Processing Script of Pattern (#1937)

* Create PrePost Pattern designer.js

Mapping of reference fields from patterns like location,manufacturer.

* Create Pre README.md

Author: ChandBasha-code

Specialized Areas/ITOM/Discovery/Pre README.md

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+# ServiceNow Discovery Pre Sensor Script: IP Router Association
+
+This script is a **ServiceNow Discovery Pre Sensor Script** designed to enrich discovery payload data before it reaches the **Identification and Reconciliation Engine (IRE)**.  
+
+It focuses on linking **Interface Cards (`cmdb_ci_interface_card`)** to their parent **IP Routers (`cmdb_ci_ip_router`)** by resolving the router name to its corresponding `sys_id` in the CMDB.
+
+
+## Overview
+
+When ServiceNow Discovery runs a pattern that identifies multiple components (e.g., routers and their interface cards), some payload items may contain **router names instead of sys_ids**.  
+The IRE requires sys_ids for accurate relationship building.  
+
+This script ensures that:
+- The `u_configuration_item` field on interface cards is replaced with the actual `sys_id` of the corresponding router.
+- The router’s `managed_by_group` field is also copied to the interface card record.
+- Payload is properly formatted and ready for IRE ingestion.
+
+##  Script Logic
+
+### Step-by-step Flow
+1. **Parse Payload:**  
+   Converts the input payload JSON string into an object for processing.
+
+2. **Iterate Items:**  
+   Loops through each payload item and filters those with `className = cmdb_ci_interface_card`.
+
+3. **Router Resolution:**  
+   For each interface card:
+   - Reads the router name from `u_configuration_item`.
+   - Searches for a matching router record in `cmdb_ci_ip_router`.
+   - If found:
+     - Replaces the router name with its `sys_id`.
+     - Copies the router’s `managed_by_group` value.
+
+4. **Return Updated Payload:**  
+   Returns the modified payload back to Discovery for further processing by the IRE.
+
+---
+
+##  Example Behavior
+
+### **Before Script Execution**
+```json
+{
+  "items": [
+    {
+      "className": "cmdb_ci_interface_card",
+      "values": {
+        "name": "Router-1/Gigabit0/1",
+        "u_configuration_item": "Router-1"
+      }
+    }
+  ]
+}
+
+### **After Script Execution**
+{
+  "items": [
+    {
+      "className": "cmdb_ci_interface_card",
+      "values": {
+        "name": "Router-1/Gigabit0/1",
+        "u_configuration_item": "1b23cdef6f3123006a12ff3b8b3ee490",
+        "managed_by_group": "287ebd7da9fe198100f92cc8d1d2154e"
+      }
+    }
+  ]
+}
+

Specialized Areas/ITOM/Discovery/PrePost Pattern designer.js

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+/*
+ * Pre sensor: You can change payload before it will be proccesed by Identification Engine.
+ * Use IEJsonUtility in order to add relevant information to the payload
+ * Input parameters in Pre sensor mode: payload, patternIds
+ */
+
+
+var rtrn = {};
+
+// parsing the json string to a json object
+var payloadObj = JSON.parse(payload);
+
+// Clearing payload string to save memory
+payload = null;
+
+// Put your business logic here
+var handlegrIpRouterdata = function() {
+
+    gs.info('PD: handlegrIpRouter');
+
+    var ipRouterName = '';
+
+    var payloadItems = payloadObj.items;
+
+    for (var i = 0; i < payloadItems.length; i++) {
+
+        if (payloadItems[i].className === 'cmdb_ci_interface_card') { //Get Child class data  
+
+            var currentItem = payloadItems[i];
+
+            ipRouterName = currentItem.values.u_configuration_item;
+
+        
+
+            if (ipRouterName && ipRouterName.length) {
+
+                var grIpRouter = new GlideRecord('cmdb_ci_ip_router');
+
+                if (grIpRouter.get('name', ipRouterName)) { 
+
+                    
+
+                    currentItem.values.u_configuration_item = grIpRouter.sys_id + '';
+					currentItem.values.managed_by_group = grIpRouter.managed_by_group + '';
+
+                }
+
+			
+
+            }
+
+        }
+
+    }
+
+};
+handlegrIpRouterdata();
+// For node logger, please use: prePostNodeLogger.info\warn\error\debug(prePostLogPrefix + '<YOUR_LOG_STATEMENT>')
+
+// You can return a message and a status, on top of the input variables that you MUST return.
+// Returning the payload as a Json String is mandatory in case of a pre sensor script, and optional in case of post sensor script.
+// If you want to terminate the payload processing due to your business logic - you can set isSuccess to false.
+rtrn = {
+	'status': {
+		'message': 'Enter your message here',
+		'isSuccess' :true
+	},
+	'patternId': patternId,
+	'payload': JSON.stringify(payloadObj)
+};