ApplicationDbContext

The ApplicationDbContext class is a crucial part of the infrastructure layer, serving as the bridge between the domain and the database. It extends DbContext and implements IUnitOfWork, providing methods for saving changes and publishing domain events.

Key Components

• Constructor: Initializes the context with DbContextOptions and an IPublisher for domain events.
• OnModelCreating: Applies configurations from the assembly.
• SaveChangesAsync: Overrides the default method to include domain event publishing and handles concurrency exceptions.
• PublishDomainEventsAsync: Publishes domain events using the _publisher.

public sealed class ApplicationDbContext : DbContext, IUnitOfWork
{
    private readonly IPublisher _publisher;
    public ApplicationDbContext(DbContextOptions options, IPublisher publisher) : base(options)
    {
        _publisher = publisher;
    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.ApplyConfigurationsFromAssembly(typeof(ApplicationDbContext).Assembly);
        base.OnModelCreating(modelBuilder);
    }

    public override async Task<int> SaveChangesAsync(CancellationToken cancellationToken = default)
    {
        try
        {
            var result = await base.SaveChangesAsync(cancellationToken);
            await PublishDomainEventsAsync();
            return result;
        }
        catch (DbUpdateConcurrencyException ex)
        {
            throw new ConcurrencyException("Concurrency exception occured.", ex);
        }
    }

    private async Task PublishDomainEventsAsync()
    {
        var domainEvents = ChangeTracker
            .Entries<Entity>()
            .Select(entry => entry.Entity)
            .SelectMany(entity =>
            {
                var domainEvents = entity.GetDomainEvents();
                entity.ClearDomainEvents();
                return domainEvents;
            })
        .ToList();

        foreach (var domainEvent in domainEvents)
        {
            await _publisher.Publish(domainEvent);
        }
    }
}