Prevent invalid used ID's

Server-Side Components/Business Rules/Prevent Null User ID/ReadME.md

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+
+#  Prevent Invalid User ID
+
+## Overview
+This **ServiceNow Business Rule** prevents inserting or updating a record when:
+- `user_name` is missing or invalid.
+- Both `first_name` and `last_name` are missing or invalid.
+
+## Functionality Breakdown
+
+### 1. `isInvalid(value)`
+- Detects invalid values in user fields.
+- Returns `true` if:
+  - Value is `null`, `undefined`, or empty (`""`)
+  - Value (after trimming spaces and lowering case) equals `"null"`
+
+Example:
+```javascript
+isInvalid(null);        // true
+isInvalid("");          // true
+isInvalid("NULL");      // true
+isInvalid("john");      // false
+```
+
+### 2. `current.setAbortAction(true)`
+- Stops the record from being inserted or updated.
+- Used inside **Before Business Rules**.
+- Prevents saving invalid data to the database.
+
+### 3. `gs.addErrorMessage("...")`
+- Displays a user-friendly error message at the top of the form.
+- Helps users understand *why* the save was blocked.
+
+
+##  Notes
+- Case-insensitive — handles "null", "NULL", "Null", etc.  
+- Works best in **Before Business Rules** to stop invalid data before saving.  
+- Adding `gs.addErrorMessage()` helps users understand the validation reason.
+

Server-Side Components/Business Rules/Prevent Null User ID/script.js

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+(function executeRule(current, previous) {
+    // Utility function to validate if a field is null, empty, or contains "null"/"NULL"
+    function isInvalid(value) {
+        return !value || value.toString().trim().toLowerCase() === "null";
+    }
+
+    // Abort action if the user_name field is invalid
+    if (isInvalid(current.user_name)) {
+        gs.addErrorMessage("User name is invalid");
+        current.setAbortAction(true);
+    }
+
+    // Abort action if both first_name and last_name are invalid
+    if (isInvalid(current.first_name) && isInvalid(current.last_name)) {
+        gs.addErrorMessage("Either first name or last name must be provided");
+        current.setAbortAction(true);
+    }
+
+})(current, previous);