AO.RowLogging 1.0.0

Override your DbContext SaveChanges behavior to track changes to select entity types in your applications.

This is inspired by SQL Server change tracking, adapted for PostgreSQL and EF Core. There's no Postgres-specific features used however, so it should work with any relational database provider for EF Core.

In a nutshell

• Implement IRowLogDbContext on your DbContext. This gives you two tables RowLog and RowLogMarker.
• For each table that needs change tracking, implement IRowLoggable on the corresponding entity type. This lets you define specific properties to track.
• Override your DbContext SaveChangesAsync method so that does three things, using methods from DbContextExtensions:
  • PrepareRowLogs scans the DbContext.ChangeTracker for IRowLoggable entities. This captures before/after states of modified rows in tracked entities in memory.
  • call the base.SaveChangesAsync method. This saves the data you were going to save originally.
  • call SaveRowLogs followed by another base.SaveChangesAsync call. This stores the before/after states of modified rows in the RowLog table.

Next steps

• Implement a consumer service that inherits from RowLogConsumer to do something with the row log data. This is where you can implement any custom logic that needs to happen when certain changes are detected, such as updating caches and report rollups, triggering notifications or pushing to other message queues. The base class handles the boilerplate of querying for changes and advancing the tracking marker.
• Use RowLoggerCleanup with Coravel to clean up old change tracking data. This is the closest you get to SQL Server's automatic cleanup of change tracking data.

EF Core Notes

Be sure to add your own configuration for the RowLog and RowLogMarker entities in your DbContext OnModelCreating method. This is required to set up the relationships and indexes properly. This is not part of the base package since you may want to customize the schema or add additional properties.

<details> <summary>But here's what I use...</summary>

public class RowLogConfiguration : IEntityTypeConfiguration<RowLog>
{
  public void Configure(EntityTypeBuilder<RowLog> builder)
  {
    builder.ToTable("RowLogs", "logs");
    builder.Property(x => x.TableName).IsRequired().HasMaxLength(100);
    builder.HasIndex(e => new { e.TableName, e.RowId });
  }
}

public class RowLogMarkerConfiguration : IEntityTypeConfiguration<RowLogMarker>
{
  public void Configure(EntityTypeBuilder<RowLogMarker> builder)
  {
    builder.ToTable("RowLogMarkers", "logs");
    builder.Property(x => x.Name).IsRequired().HasMaxLength(100);
    builder.HasIndex(e => e.Name).IsUnique();
  }
}

</details>

Comparison: SQL Server Change Tracking vs Row Logger