DKNet

Stage new entities found in collection navigations

Part of DKNet.EfCore.Extensions. Walk collection navigations from possible updating roots and add discovered new children in one batch.

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();
var parent = new Item { Name = "Coffee" };
db.Add(parent);
await db.SaveChangesAsync();
db.ChangeTracker.AutoDetectChangesEnabled = false;
parent.Name = "Coffee beans";
db.Entry(parent).Property(x => x.Name).IsModified = true;
parent.Children.Add(new Child());
Console.WriteLine(db.GetNewEntitiesFromNavigations(db.Entry(parent)).Count()); // 1
Console.WriteLine(await db.AddNewEntitiesFromNavigations()); // 1: the child is considered new
db.ChangeTracker.AutoDetectChangesEnabled = true;
await db.SaveChangesAsync();

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; } = "";
    public List<Child> Children { get; set; } = [];
}
public sealed class Child
{
    public int Id { get; set; }
    public int ItemId { get; set; }
}

AddNewEntitiesFromNavigations selects Modified or Detached tracked roots, reads collection navigation values, checks each child with IsNewEntity and adds the resulting batch.

GetPossibleUpdatingEntities calls DetectChanges and selects Detached/Modified entries. GetNewEntitiesFromNavigations(entry) scans one root; its parameterless form scans those possible roots. GetCollectionNavigations(Type) selects collection, non-shadow INavigation metadata.

⚠️ Gotchas & limits

This is a single-level collection walk. Reference navigations and skip navigations are not selected; Unchanged and Added roots are excluded by the automatic root selector.
EF Core detection can already stage children. The example disables automatic detection so the explicit-root overload sees a Detached child first. The batch helper calls DetectChanges, then stages the child returned by its scan. Added children also satisfy IsNewEntity, so the count can include already tracked additions.
GetNavigationValues(object, INavigation) reads a property or backing field and returns an empty sequence when no enumerable is available. The collection walker itself uses EF entry collection access.
The discovery sequence can yield the same child through multiple roots; do not interpret the returned count as a unique database insertion count.

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