DbContext Interceptor Change

src/E13.Common.Data.Db/BaseDbContext.cs

@@ -16,14 +16,19 @@
 
 namespace E13.Common.Data.Db
 {
-    public abstract class BaseDbContext : DbContext
+    public abstract class BaseDbContext : DbContext, IAuditContext
     {
         /// <summary>
         /// The user name used when the user name is null
         /// </summary>
         public const string UnknownUser = "*Unknown";
 
         protected ILogger Logger { get;}
+
+        public string? AuditUser { get; set; }
+
+        public string? Source { get; set; }
+
         protected BaseDbContext(DbContextOptions options, ILogger logger)
             : base(options)
         {
@@ -42,26 +47,6 @@ protected override void OnModelCreating(ModelBuilder modelBuilder)
             base.OnModelCreating(modelBuilder);
         }
 
-        public int SaveChanges(string user, string? source = null)
-        {
-            if(source == null)
-            {
-                var caller = new StackFrame(1).GetMethod() 
-                    ?? throw new Exception("Unable to determine the calling method source from new StackFrame(1).GetMethod()");
-
-                source = $"{caller.DeclaringType?.FullName}.{caller.Name}";
-            }
-
-            TagEntries(source, user);
-            var result = base.SaveChanges();
-
-            // saving after a reload effectively clears the change tracker affecting no records
-            Reload();
-            base.SaveChanges();
-
-            return result;
-        }
-
         /// <summary>
         /// This is used by E13.Common.Data.Db.Tests in order to allow TestDbContext.TestSeed() to seed
         /// data without going through the TagEntries.
@@ -81,70 +66,17 @@ internal int SaveChanges_NoTagEntries()
 
         public override int SaveChanges()
         {
-            var caller = new StackFrame(1).GetMethod()!; // This is safe because the method is called from somewhere
+            // 1 – Get caller outside EF
+            var caller = new StackFrame(1).GetMethod();
+            var source = $"{caller?.DeclaringType?.FullName}.{caller?.Name}";
 
-            return SaveChanges(UnknownUser, $"{caller.DeclaringType}.{caller.Name}");
-        }
+            // 2 – Stash it in the scoped audit context (injected)
+            Source = source ?? "Unknown";
+            AuditUser = AuditUser ?? UnknownUser;
 
-        public void Reload() => ChangeTracker.Entries()
-            .Where(e => e.Entity != null).ToList()
-            .ForEach(e => e.State = EntityState.Detached);
-
-        private void TagEntries(string source, string user)
-        {
-            var entries = ChangeTracker.Entries().Where(e =>
-                e.Entity is IEntity &&
-                (e.State == EntityState.Added || e.State == EntityState.Modified || e.State == EntityState.Deleted)
-            );
-
-            Logger.LogInformation($"ChangeTracker Contains {entries.Count()}/{ChangeTracker.Entries().Count()} in an Added or Modified state.");
-
-            foreach (var entry in entries)
-            {
-                Logger.LogDebug($"Entity: {entry.Entity.GetType().Name}, State: {entry.State}");
-                var utcNow = DateTime.UtcNow;
-
-                if (entry.State == EntityState.Added && entry.Entity is ICreatable)
-                {
-                    SetProperty(entry.Entity, "Created", utcNow);
-                    SetProperty(entry.Entity, "CreatedBy", user);
-                    SetProperty(entry.Entity, "CreatedSource", source);
-                }
-
-                if (entry.Entity is IModifiable)
-                {
-                    SetProperty(entry.Entity, "Modified", utcNow);
-                    SetProperty(entry.Entity, "ModifiedBy", user);
-                    SetProperty(entry.Entity, "ModifiedSource", source);
-                }
-
-                if (entry.Entity is IDeletable deletable)
-                {
-                    if (entry.State == EntityState.Deleted)
-                    {
-                        entry.State = EntityState.Modified;
-                        SetProperty(entry.Entity, "Deleted", utcNow);
-                        SetProperty(entry.Entity, "DeletedBy", user);
-                        SetProperty(entry.Entity, "DeletedSource", source);
-                    }
-                    else if (deletable.Deleted != null || deletable.DeletedBy != null || deletable.DeletedSource != null)
-                    {
-                        entry.State = EntityState.Modified;
-                        SetProperty(entry.Entity, "Deleted", null);
-                        SetProperty(entry.Entity, "DeletedBy", null);
-                        SetProperty(entry.Entity, "DeletedSource", null);
-                    }
-                }
-            }
+            // 3 – Proceed. Interceptors now have Source & User.
+            return base.SaveChanges();
         }
 
-        private void SetProperty(object entity, string propertyName, object? value)
-        {
-            var property = entity.GetType().GetProperty(propertyName, BindingFlags.Public | BindingFlags.Instance);
-            if (property != null && property.CanWrite)
-            {
-                property.SetValue(entity, value);
-            }
-        }
     }
 }

src/E13.Common.Data.Db/IAuditContext.cs

@@ -0,0 +1,14 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace E13.Common.Data.Db
+{
+    public interface IAuditContext
+    {
+        string? AuditUser { get; }
+        string? Source { get; }
+    }
+}

src/E13.Common.Data.Db/Interceptors/CreatableInterceptor.cs

@@ -0,0 +1,30 @@
+using E13.Common.Domain;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Diagnostics;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace E13.Common.Data.Db.Interceptors
+{
+    public sealed class CreatableInterceptor : SaveChangesInterceptor
+    {
+        public override InterceptionResult<int> SavingChanges(
+            DbContextEventData data,
+            InterceptionResult<int> result)
+        {
+            var auditContext = data.Context as IAuditContext ?? throw new Exception("Audit context is not set.");
+
+            foreach (var entry in data.Context!.ChangeTracker.Entries<ICreatable>()
+                         .Where(e => e.State == EntityState.Added))
+            {
+                entry.Entity.Created = DateTime.UtcNow;
+                entry.Entity.CreatedBy = auditContext.AuditUser;
+                entry.Entity.CreatedSource = auditContext.Source;
+            }
+            return base.SavingChanges(data, result);
+        }
+    }
+}

src/E13.Common.Data.Db/Interceptors/ModifiableInterceptor.cs

@@ -0,0 +1,30 @@
+using E13.Common.Domain;
+using Microsoft.EntityFrameworkCore.Diagnostics;
+using Microsoft.EntityFrameworkCore;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace E13.Common.Data.Db.Interceptors
+{
+    public sealed class ModifiableInterceptor : SaveChangesInterceptor
+    {
+        public override InterceptionResult<int> SavingChanges(
+            DbContextEventData data,
+            InterceptionResult<int> result)
+        {
+            var auditContext = data.Context as IAuditContext ?? throw new Exception("Audit context is not set.");
+
+            foreach (var entry in data.Context!.ChangeTracker.Entries<IModifiable>()
+                         .Where(e => e.State is EntityState.Added or EntityState.Modified))
+            {
+                entry.Entity.Modified = DateTime.UtcNow;
+                entry.Entity.ModifiedBy = auditContext.AuditUser;
+                entry.Entity.ModifiedSource = auditContext.Source;
+            }
+            return base.SavingChanges(data, result);
+        }
+    }
+}

src/E13.Common.Data.Db/Interceptors/SoftDeleteInterceptor.cs

@@ -0,0 +1,44 @@
+using E13.Common.Domain;
+using Microsoft.EntityFrameworkCore.Diagnostics;
+using Microsoft.EntityFrameworkCore;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace E13.Common.Data.Db.Interceptors
+{
+    public sealed class SoftDeleteInterceptor : SaveChangesInterceptor
+    {
+        public override InterceptionResult<int> SavingChanges(
+            DbContextEventData data,
+            InterceptionResult<int> result)
+        {
+            var auditContext = data.Context as IAuditContext ?? throw new Exception("Audit context is not set.");
+
+            foreach (var entry in data.Context!.ChangeTracker.Entries<IDeletable>())
+            {
+                if (entry.State == EntityState.Deleted)
+                {
+                    entry.State = EntityState.Modified;
+                    entry.Entity.Deleted = DateTime.UtcNow;
+                    entry.Entity.DeletedBy = auditContext.AuditUser;
+                    entry.Entity.DeletedSource = auditContext.Source;
+                }
+                else if (entry.State == EntityState.Modified &&
+                         (entry.Entity.Deleted != null ||
+                          entry.Entity.DeletedBy != null ||
+                          entry.Entity.DeletedSource != null))
+                {
+                    // “undelete” scenario
+                    entry.Entity.Deleted = null;
+                    entry.Entity.DeletedBy = null;
+                    entry.Entity.DeletedSource = null;
+                }
+            }
+            return base.SavingChanges(data, result);
+        }
+    }
+
+}

test/E13.Common.Data.Db.Tests/BaseDbContext_ICreatableTests.cs

@@ -1,3 +1,4 @@
+using E13.Common.Data.Db.Interceptors;
 using E13.Common.Data.Db.Tests.Sample;
 using FluentAssertions;
 using Microsoft.EntityFrameworkCore;
@@ -16,10 +17,17 @@ public class BaseDbContext_ICreatableTests
         public void Setup()
         {
             var services = new ServiceCollection();
-            services.AddDbContext<TestDbContext>(o =>
+            services.AddScoped<CreatableInterceptor>();
+            services.AddScoped<ModifiableInterceptor>();
+            services.AddScoped<SoftDeleteInterceptor>();
+            services.AddDbContext<IAuditContext, TestDbContext>((sp, o) =>
             {
                 o.UseInMemoryDatabase($"{Guid.NewGuid()}");
                 o.EnableSensitiveDataLogging();
+                o.AddInterceptors(
+                    sp.GetRequiredService<CreatableInterceptor>(),
+                    sp.GetRequiredService<ModifiableInterceptor>(),
+                    sp.GetRequiredService<SoftDeleteInterceptor>());
             });
 
             Context = services.BuildServiceProvider().GetService<TestDbContext>();
@@ -72,9 +80,10 @@ public void SaveChanges_NamedUser_CreatedByNamedUser()
             if (Context == null)
                 throw new Exception("TestDbContext did not Setup() successfully");
 
+            Context.AuditUser = nameof(SaveChanges_NamedUser_CreatedByNamedUser);
             var id = Guid.NewGuid();
             Context.Creatables.Add(new TestCreatable { Id = id });
-            Context.SaveChanges(nameof(SaveChanges_NamedUser_CreatedByNamedUser));
+            Context.SaveChanges();
 
             var arranged = Context.Creatables.First(e => e.Id == id);
 

test/E13.Common.Data.Db.Tests/BaseDbContext_IDeletableTests.cs

@@ -1,3 +1,4 @@
+using E13.Common.Data.Db.Interceptors;
 using E13.Common.Data.Db.Tests.Sample;
 using FluentAssertions;
 using Microsoft.EntityFrameworkCore;
@@ -16,7 +17,12 @@ public class BaseDbContext_IDeletableTests
         public void Setup()
         {
             var services = new ServiceCollection();
-            services.AddDbContext<TestDbContext>(o => o.UseInMemoryDatabase($"{Guid.NewGuid()}"));
+            services.AddDbContext<TestDbContext>(o => {
+                o.UseInMemoryDatabase($"{Guid.NewGuid()}");
+                o.AddInterceptors(new CreatableInterceptor());
+                o.AddInterceptors(new ModifiableInterceptor());
+                o.AddInterceptors(new SoftDeleteInterceptor());
+            });
 
             Context = services.BuildServiceProvider().GetService<TestDbContext>();
             if (Context == null)
@@ -62,12 +68,13 @@ public void SaveChangesForUser_Deleting_SetsDeletedBy()
             if (Context == null)
                 throw new Exception("TestDbContext did not Setup() successfully");
 
+            Context.AuditUser = nameof(SaveChangesForUser_Deleting_SetsDeletedBy);
             Context.Deletable.IgnoreQueryFilters().Count().Should().Be(1);
             Context.Deletable.IgnoreQueryFilters().Count(e => e.DeletedBy == null).Should().Be(1);
             var arranged = Context.Deletable.IgnoreQueryFilters().First(f => f.Deleted == null);
 
             Context.Deletable.Remove(arranged);
-            Context.SaveChanges(nameof(SaveChangesForUser_Deleting_SetsDeletedBy));
+            Context.SaveChanges();
 
             Context.Deletable.IgnoreQueryFilters().Count().Should().Be(1);
             Context.Deletable.IgnoreQueryFilters().Count(e => e.DeletedBy == null).Should().Be(0);

test/E13.Common.Data.Db.Tests/BaseDbContext_IModifiableTests.cs

@@ -1,3 +1,4 @@
+using E13.Common.Data.Db.Interceptors;
 using E13.Common.Data.Db.Tests.Sample;
 using FluentAssertions;
 using Microsoft.EntityFrameworkCore;
@@ -16,7 +17,12 @@ public class BaseDbContext_IModifiableTests
         public void Setup()
         {
             var services = new ServiceCollection();
-            services.AddDbContext<TestDbContext>(o => o.UseInMemoryDatabase($"{Guid.NewGuid()}"));
+            services.AddDbContext<TestDbContext>(o => {
+                o.UseInMemoryDatabase($"{Guid.NewGuid()}");
+                o.AddInterceptors(new CreatableInterceptor());
+                o.AddInterceptors(new ModifiableInterceptor());
+                o.AddInterceptors(new SoftDeleteInterceptor());
+            });
 
             Context = services.BuildServiceProvider().GetService<TestDbContext>();
 
@@ -99,12 +105,14 @@ public void SaveChanges_NamedUser_UpdatesModifiedBy()
             if (Context == null)
                 throw new Exception("TestDbContext did not Setup() successfully");
 
+
+            Context.AuditUser = nameof(SaveChanges_NamedUser_UpdatesModifiedBy);
             var arranged = Context.Modifiables.First();
             arranged.Text.Should().BeEmpty();
 
             //act
             arranged.Text = $"{Guid.NewGuid()}";
-            Context.SaveChanges(nameof(SaveChanges_NamedUser_UpdatesModifiedBy));
+            Context.SaveChanges();
 
             var assert = Context.Modifiables.First();
             assert.ModifiedBy.Should().Be(nameof(SaveChanges_NamedUser_UpdatesModifiedBy));
@@ -116,11 +124,11 @@ public void SaveChanges_NamedUser_ModifiedUpdates()
             if (Context == null)
                 throw new Exception("TestDbContext did not Setup() successfully");
 
+            Context.AuditUser = nameof(SaveChanges_NamedUser_ModifiedUpdates);
             var arranged = Context.Modifiables.First();
 
             //act
             arranged.Text = $"{Guid.NewGuid()}";
-            Context.SaveChanges(nameof(SaveChanges_NamedUser_ModifiedUpdates));
 
             var actual = Context.Modifiables.First();
             actual.Modified.Should().NotBeNull();

test/E13.Common.Data.Db.Tests/Sample/TestCreatable.cs

@@ -12,8 +12,8 @@ public class TestCreatable : ICreatable
         public Guid Id { get; set; }
         public string Text { get; set; } = string.Empty;
 
-        public string? CreatedBy { get; set; } = "CreatedBy";
-        public string? CreatedSource { get; set; } = "CreatedSource";
+        public string? CreatedBy { get; set; }
+        public string? CreatedSource { get; set; }
         public DateTime? Created { get; set; }
     }
 }