barkman/barkmanAPI/inventoryModel.cs

using Microsoft.EntityFrameworkCore;
using System;
using System.Collections.Generic;

public class InventoryContext : DbContext
{
    public int Id {get; set;} 
    public string Name { get; set; }
    public string Brand { get; set; }
    public string? SerialNumber { get; set; }
    public string?  Status { get; set; }
    public float? RentalPrice { get; set; }
    public float? ReplacementCost { get; set; }
    public string? Notes { get; set; }
    
    public string DbPath { get; }

    public InventoryContext()
    {
        var folder = Environment.SpecialFolder.LocalApplicationData;
        var path = Environment.GetFolderPath(folder);
        DbPath = System.IO.Path.Join(path, "blogging.db");
    }

    // The following configures EF to create a Sqlite database file in the
    // special "local" folder for your platform.
    protected override void OnConfiguring(DbContextOptionsBuilder options)
        => options.UseSqlite($"Data Source={DbPath}");
    
}

public class InventoryDb
{

    public static List<InventoryItem> GetInventory() 
    {
        return  _inventory;
    } 

    public static InventoryItem ? GetInventory(int id) 
    {
        return  _inventory.SingleOrDefault(item => item.Id == id);
    } 

    public static InventoryItem CreateInventoryItem(InventoryItem item) 
    {
         _inventory.Add(item);
        return item;
    }

    public static InventoryItem UpdateItem(InventoryItem update) 
    {
         _inventory =  _inventory.Select(item =>
        {
            if (item.Id == update.Id)
            {
                item.Name = update.Name;
            }
            return item;
        }).ToList();
        return update;
    }

    public static void RemoveItem(int id)
    {
         _inventory =  _inventory.FindAll(item => item.Id != id).ToList();
    }
}