How to refresh Entity Framework Core DbContext of ASP.NET Core project when connection string in web.config is changed?

I have an ASP.NET Core 8 project with Entity Framework Core. The connection string is taken from web.config in the root folder. While debugging in Visual Studio 2022, I enabled Hot Reload. I have figured out way to refresh DbContext when hot reload is triggered.

I use this code:

[assembly: System.Reflection.Metadata.MetadataUpdateHandler(typeof(HotReloadManager))]
namespace xxx
{
    internal static class HotReloadManager
    {
        public static void ClearCache(Type[]? types)
        {
            // Clear any caches if needed
        }

        public static void UpdateApplication(Type[]? types)
        { 
            using var context = new xxxDbContext();
            context.Database.EnsureCreated();
        }
    }
}

It works fine while hot reloading. DbContext is refreshed. Then the next thing is when I edit connection string in web.config, I find that this will not trigger hot reload. How can I achieve that?

New thought: If I want to use new connection string when DbContext is created, there is no necessary to involve hot reload.The only thing I need to do is to make sure OnConfiguring uses lates value from web.config file every time DbContext is created.

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            // make sure this connectionString value is always from fresh web.conifg file, not from ConfigurationManager cache
            string? connectionString = xxx;
            optionsBuilder.UseSqlServer(connectionString, providerOptions =>
            {
                providerOptions.CommandTimeout(300);
            });
        }

The methods have already been discussed in comments, which is to use OpenMappedExeConfiguration. But if website is with appSettings.json, then IOptionsSnapshot can help.

Solution

Have you tried using IOptions? Specifically IOptionsMonitor or IOptionsSnapshot. See below for additional info:

IOptionsMonitor has an OnChange method that will be called when the underlying configuration source changes. Or you can use IOptionsSnapshot which might be better if DbContext is a scoped/transient service.

This way you can also omit the HotReloadManager part.