DKNet

Retry a save after a concurrency conflict

Part of DKNet.EfCore.Extensions. Wrap an async save in a bounded retry loop using IEfCoreExceptionHandler.

Use the console-project setup in the Quick Start, then replace Program.cs with this example.

using Microsoft.EntityFrameworkCore;
using DKNet.EfCore.Extensions.Extensions;

using var connection = new Microsoft.Data.Sqlite.SqliteConnection("Data Source=:memory:");
connection.Open();
var o = new DbContextOptionsBuilder<DemoDb>();
o.UseSqlite(connection);
await using var db = new DemoDb(o.Options);
await db.Database.EnsureCreatedAsync();
db.Add(new Item { Name = "Coffee" });
Console.WriteLine(await db.SaveChangesWithConcurrencyHandlingAsync()); // 1

public sealed class DemoDb(DbContextOptions<DemoDb> options) : DbContext(options)
{
    public DbSet<Item> Items => Set<Item>();
}
public sealed class Item
{
    public int Id { get; set; }
    public string Name { get; set; } = "";
}

The default EfCoreExceptionHandler rethrows conflicts with no entries. Otherwise it reloads database values into OriginalValues while preserving CurrentValues, then requests another save. It uses the structured Entries collection, not message matching.

⚙️ Configuration reference

Option	Type	Default	Effect
handler	IEfCoreExceptionHandler?	new default handler	Handles concurrency exceptions only.
MaxRetryCount	int	3 on interface	Retry limit after initial save.
cancellationToken	CancellationToken	default	Forwarded to save and handler.
Default handler logger	ILogger<EfCoreExceptionHandler>?	null	Log conflict warning when supplied.

EfConcurrencyResolution contains RethrowException, IgnoreChanges and RetrySaveChanges. Pass a custom handler explicitly for direct calls.

⚠️ Gotchas & limits

• The default maximum is 3 retries after the first attempt. Exhaustion returns 0; it does not throw the last concurrency exception.
• IgnoreChanges also returns 0 but does not itself detach entries or clear pending changes. Your handler owns any state adjustment.
• AddEfCoreExceptionHandler<TDbContext,THandler>() registers a keyed transient service. This direct save helper uses the handler argument or constructs its default; it does not resolve that registration automatically.
• A missing database row leaves its entry unchanged during reload, so repeated conflict can exhaust retries. Other exception types propagate.

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