The trigger executed twice

Whenever I do insert an entity with its related entity, the trigger is executed twice. I don’t think there’s a problem in my code though.

CreateStockInputWindow.xaml.cs

...
                    dbContext.StockInputLogs.Add(
                        new StockInputLog()
                        {
                            UserId = Session.Instance.User!.Id,
                            Amount = inputAmount,
                            Stock = new Stock()
                            {
                                ExpirationDate = expirationDate,
                                ItemId = Item!.Id,
                                Amount = inputAmount,
                            }
                        }
                    );
...

StockInputLog.cs

namespace WarehouseApp.Models;

public class StockInputLog : BaseModel
{
    public int StockId { get; set; }

    public int UserId { get; set; }

    public int Amount { get; set; }

    public Stock? Stock { get; set; }

    public User? User { get; set; }
}

Stock.cs

using System;
using System.Collections.Generic;

namespace WarehouseApp.Models;

public class Stock : BaseModel
{
    public DateTime ExpirationDate { get; set; }

    public int ItemId { get; set; }

    public int Amount { get; set; }

    public Item? Item { get; set; }

    public List<StockInputLog>? StockInputLogs { get; set; }

    public List<StockOutputLog>? StockOutputLogs { get; set; }
}

The current workaround is to insert an entity, then call dbContext.SaveChanges(), and finally insert the related entity by selecting the previous entity’s id and do dbContext.SaveChanges()

Example.cs

        dbContext.AddRange(
            new User(username: "admin", name: "Admin", password: "Password", isAdmin: true),
            new User(username: "user", name: "User", password: "Password", isAdmin: false)
        );

        dbContext.AddRange(
            new Item(barcode: "8991038775416", name: "Lorem ipsum ", quantifier: "dus"),
            new Item(
                barcode: "8991038775417",
                name: "Dolor sit amet",
                quantifier: "kg",
                totalAmount: 0
            ),
            new Item(
                barcode: "8991038775418",
                name: "Consectetur adipiscing",
                quantifier: "m",
                totalAmount: 0
            )
        );

        dbContext.SaveChanges();

        dbContext.Add(new Stock() { ItemId = 1, ExpirationDate = DateTime.Now.AddDays(10) });

        dbContext.SaveChanges();

        dbContext.AddRange(
            new StockInputLog() { Amount = 10, UserId = 1, StockId = 1 },
            new StockInputLog() { Amount = 20, UserId = 1, StockId = 1 },
            new StockInputLog() { Amount = 15, UserId = 1, StockId = 1 }
        );

        dbContext.SaveChanges();

But it looks ugly. Can anyone help to fix this problem? Thank you in advance

[kangzoel]

My bad, the problem is in my code, not the library. I shouldn’t have initialize the stock value, and let the StockInputLog trigger handle the initial value. Thus the code should be

CreateStockInputWindow.xaml.cs

...
                    dbContext.StockInputLogs.Add(
                        new StockInputLog()
                        {
                            UserId = Session.Instance.User!.Id,
                            Amount = inputAmount,
                            Stock = new Stock()
                            {
                                ExpirationDate = expirationDate,
                                ItemId = Item!.Id,
                                // Removed: Amount = inputAmount,
                            }
                        }
                    );
...

[kangzoel]

I don’t use dependency injection. I modified my code but it has not effect. The trigger still executed twice. These are my new codes:

DatabaseContext.cs

using System.Diagnostics;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;
using WarehouseApp.Models;

namespace WarehouseApp.Database;

public class DatabaseContext : DbContext
{
    public DbSet<Item> Items => Set<Item>();
    public DbSet<Stock> Stocks => Set<Stock>();
    public DbSet<StockInputLog> StockInputLogs => Set<StockInputLog>();
    public DbSet<StockOutputLog> StockOutputLogs => Set<StockOutputLog>();
    public DbSet<User> Users => Set<User>();

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder
            .UseSqlite("Data Source=database.sqlite")
            .EnableSensitiveDataLogging()
            .LogTo((e) => Trace.WriteLine(e))
            .UseTriggers(triggerOptions =>
            {
                triggerOptions.AddTrigger<Triggers.StockInputLogTrigger>(ServiceLifetime.Scoped);
            });
    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Stock>().HasAlternateKey(s => new { s.ItemId, s.ExpirationDate });
    }
}

StockInputLogTrigger.cs

using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using EntityFrameworkCore.Triggered;
using EntityFrameworkCore.Triggered.Lifecycles;
using WarehouseApp.Models;

namespace WarehouseApp.Triggers;

internal class StockInputLogTrigger : IBeforeSaveTrigger<StockInputLog>, IBeforeSaveCompletedTrigger
{
    readonly HashSet<StockInputLog> _processedEntities = new();

    public Task BeforeSave(
        ITriggerContext<StockInputLog> context,
        CancellationToken cancellationToken
    )
    {
        if (!_processedEntities.Contains(context.Entity))
        {
            _processedEntities.Add(context.Entity);

            var stock = context.Entity.Stock;

            switch (context.ChangeType)
            {
                case ChangeType.Added:
                    stock!.Amount += context.Entity.Amount;
                    break;
                case ChangeType.Deleted:
                    stock!.Amount -= context.Entity.Amount;
                    break;
            }
        }

        return Task.CompletedTask;
    }

    public Task BeforeSaveCompleted(CancellationToken _)
    {
        _processedEntities.Clear();

        return Task.CompletedTask;
    }
}

I think I’ll use my workaround instead, for the time being, by inserting entities independently (no nesting entity), until the problem is fixed