RazorPages - Efficiency of a database context in a PageModel

Question

Hi all! I'm wondering how a database context object from SQL -> EF generation would work if I place it as a variable in a RazorPages PageModel. So:

1. I have my own PageModel class which I inherit from the base RazorPages PageModel:

    public class BasePageModel : PageModel

1. I add my DbContext (that is generated from SQL using the Scaffold tool) as a variable in the class:

    public class BasePageModel : PageModel
    {
        protected DatabaseContext theDB = new();

1. Then every page in my website can use this DbContext.

Is this efficient? Will the same object be used in every page with persistence? Or is this the same as just adding the variable to every RazorPage? Or is it less efficient? Or is there a better way? Thanks for your help.

Regards Geoff

Answer 1

a new Razor model instance is created on each request. so defining a variable in a base class is the same as defining it in every inheritor class.

as suggested, it more common to inject a db context via services.

Answer 2

Best to use a DbContext per page.

Program.cs

public class Program
{
    public static void Main(string[] args)
    {
        var builder = WebApplication.CreateBuilder(args);
    builder.Services.AddRazorPages();


builder.Services.AddDbContextPool<Context>(options =>
    options.UseSqlServer(
        Configurations.GetConfigurationRoot()
            .GetConnectionString("DefaultConnection")));

var app = builder.Build();

Example usage for a page

public class CustomersModel : PageModel
{
    private readonly Context _context;
    private readonly ILogger<IndexModel> _logger;
    public CustomersModel(ILogger<IndexModel> logger, Data.Context context)
    {
        _context = context;
        _logger = logger;
    }

    public IList<Customers> Customers { get;set; } = default!;

    public async Task OnGetAsync()
    {
        if (_context.Customers != null)
        {
            Customers = await _context.Customers
                .Include(c => c.Contact)
                .Include(c => c.ContactTypeIdentifierNavigation)
                .Include(c => c.CountryIdentifierNavigation).ToListAsync();
        }
    }
}