StockItemsHandler.cls

/**
 * A Utility class to process Stock Item records from the Stock Item Handler
 */
public with sharing class StockItemHandler {
    
    /**
     * Class constructor.
     */
    public StockItemHandler() {
        
    }
    
    public static void checkDuplicateName(List<Stock_Item__c> newStockItem) {
        
        // Need to store existing list of items in a set.
        Set<String> listOfItems = new Set<String>();
        for(Stock_Item__c listOfStock : [Select ID, Item_Name__c 
                                         From Stock_Item__c]){
               listOfItems.add(listOfStock.Item_Name__c);
                                         }
        
        // check if new item name already exists - if so, produce an error
        for(Stock_Item__c listOfStock: newStockItem){
            if(listOfItems.contains(listOfStock.Item_Name__c)){
                listOfStock.Item_Name__c.adderror('This item already exists.');
            }
        }

    }
    
    public static void deleteStockItems(List <Stock_Item__c> SID)         
    {        
        //create a list of new cases
        list <Case> newCases = new List<Case>();
        for(Stock_Item__c StockItemsDelete: SID)
        {
            // Before stock item is deleted - check if Stock on hand is not equal to 0
            // and add a new case alert someone to check the stock.
            If(StockItemsDelete.Stock_on_Hand__c != 0)
            {
                Case c = new Case ();
                c.comments = StockItemsDelete.id +' '+ StockItemsDelete.Item_Name__c +' '+ StockItemsDelete.Stock_on_Hand__c;
                c.status = 'New';
                c.Origin = 'Not Zeroed Stock Item'; 
                c.Subject = 'Please review '+ StockItemsDelete.Item_Name__c +' Inventory Level';
                newCases.add(c);
            }
        }
        insert newCases; 
    }
    
    
    public static list<Stock_Item__c> getLowStockItems() { 
                // Create list of stock items where Item Stock Is Low equals true.
                List<Stock_Item__c> STIS = [Select ID, Item_Name__c, Item_Stock_is_Low__c, Minimum_Stock_Level__c, Stock_on_Hand__c
                                            From Stock_Item__c 
                                            WHERE Item_Stock_Is_Low__c = true];
                
                System.debug('Low stock items' + STIS);
                // Return list of items that are low stock
                return STIS;
        
    }
    
    
    //Create methods here to handle the before insert, before delete and utility processes described in the requirements
    //They should accept lists of Stock_Item__c records from the trigger

    
}