To display a warning message on an Incident record/form in ServiceNow if it has a child incident

Using a Client Script

1. Create a Client Script:
   • Navigate to System Definition > Client Scripts.
   • Click on New to create a new Client Script.
   • Set the Table to incident and Type to onLoad.
2. Add Script Code:
   • Use the following script to check if the incident has any child incidents and display a warning message:

(function() {
    // Create a GlideRecord object for the Incident table
    var gr = new GlideRecord('incident');
    // Query for child incidents where the parent is the current record
    gr.addQuery('parent', current.sys_id);
    gr.query();
     // Check if any child incidents are found
    if (gr.hasNext()) {
        // Show a warning message
        g_form.addInfoMessage('This incident has one or more child incidents.');
    }
})();

Explanation:

• GlideRecord('incident'): Creates a GlideRecord object to query the Incident table.
• addQuery('parent', current.sys_id): Filters records where the parent field matches the current incident's sys_id.
• hasNext(): Checks if there are any child incidents.
• g_form.addInfoMessage(): Displays an informational message on the form.

Additional Considerations:

• Ensure that the 'parent' field in your Incident table is correctly configured to link child incidents.
• Adjust message type: If you want a more prominent warning, you could use g_form.addErrorMessage() instead of addInfoMessage(), but be cautious with error messages as they might imply more critical issues.