How to use code-first with EntityFramework-Plus' audit feature?

ef-code-first ef-migrations entity-framework-core entity-framework-plus

Question

I'm trying to setup EntityFramework Plus' Audit Auto-Save feature, but it looks like I'm stuck at something very dumb. I'm following the "Saving automatically by overriding SaveChanges & SaveChangesAsync" path, but I'm trying to use code-first as the project I'm gonna use that for has been running like that for a while now. With that said, my DbContext looks like so:

public class CadastralDbContext : DbContext
{
    public CadastralDbContext(DbContextOptions<CadastralDbContext> options) : base(options) { }

    static CadastralDbContext()
    {
        AuditManager.DefaultConfiguration.AutoSavePreAction = (context, audit) =>
           (context as CadastralDbContext).AuditEntries.AddRange(audit.Entries);
    }

    public DbSet<AuditEntry> AuditEntries { get; set; }

    public DbSet<AuditEntryProperty> AuditEntryProperties { get; set; }

    //Ommited my DbSets

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.ApplyConfigurationsFromAssembly(typeof(CadastralDbContext).Assembly);
        /*** Ignore these for now ***/
        //modelBuilder.Entity<AuditEntry>().Ignore(x => x.Properties);
        //modelBuilder.Entity<AuditEntryProperty>().Ignore(x => x.Parent);
    }

    public override int SaveChanges()
    {
        var audit = new Audit();
        audit.PreSaveChanges(this);
        var rowAffecteds = base.SaveChanges();
        audit.PostSaveChanges();

        if (audit.Configuration.AutoSavePreAction != null)
        {
            audit.Configuration.AutoSavePreAction(this, audit);
            base.SaveChanges();
        }

        return rowAffecteds;
    }

    public async Task<int> SaveChangesAsync()
    {
        return await SaveChangesAsync(CancellationToken.None);
    }

    public override async Task<int> SaveChangesAsync(CancellationToken cancellationToken)
    {
        var audit = new Audit();
        audit.PreSaveChanges(this);
        var rowAffecteds = await base.SaveChangesAsync(cancellationToken).ConfigureAwait(false);
        audit.PostSaveChanges();

        if (audit.Configuration.AutoSavePreAction != null)
        {
            audit.Configuration.AutoSavePreAction(this, audit);
            await base.SaveChangesAsync(cancellationToken).ConfigureAwait(false);
        }

        return rowAffecteds;
    }
}

}

Basically, what the tutorial says with added DbSet<AuditEntry> and DbSet<AuditEntryProperty> which are classes from the framework itself. Inspecting metadata for these, we have:

//
// Summary:
//     An audit entry.
public class AuditEntry
{
    //
    // Summary:
    //     Gets or sets the object state entry.
    [NotMapped]
    public object Entity;
    //
    // Summary:
    //     Gets or sets the object state entry.
    [NotMapped]
    public EntityEntry Entry;
    //
    // Summary:
    //     Gets or sets the parent.
    public Audit Parent;

    public AuditEntry();

    //
    // Summary:
    //     Gets or sets the identifier of the audit entry.
    [Column(Order = 0)]
    public int AuditEntryID { get; set; }
    //
    // Summary:
    //     Gets or sets who created this object.
    [Column(Order = 5)]
    [MaxLength(255)]
    public string CreatedBy { get; set; }
    //
    // Summary:
    //     Gets or sets the the date of the changes.
    [Column(Order = 6)]
    public DateTime CreatedDate { get; set; }
    //
    // Summary:
    //     Gets or sets the name of the entity set.
    [Column(Order = 1)]
    [MaxLength(255)]
    public string EntitySetName { get; set; }
    //
    // Summary:
    //     Gets or sets the name of the entity type.
    [Column(Order = 2)]
    [MaxLength(255)]
    public string EntityTypeName { get; set; }
    //
    // Summary:
    //     Gets or sets the properties.
    public List<AuditEntryProperty> Properties { get; set; }
    //
    // Summary:
    //     Gets or sets the entry state.
    [Column(Order = 3)]
    public AuditEntryState State { get; set; }
    //
    // Summary:
    //     Gets or sets the name of the entry state.
    [Column(Order = 4)]
    [MaxLength(255)]
    public string StateName { get; set; }
}

And

//
// Summary:
//     An audit entry property.
public class AuditEntryProperty
{
    //
    // Summary:
    //     Gets or sets the new value audited.
    [NotMapped]
    public PropertyEntry PropertyEntry;
    public object NewValue;
    public object OldValue;

    public AuditEntryProperty();

    //
    // Summary:
    //     Gets or sets the name of the property internally.
    [NotMapped]
    public string InternalPropertyName { get; set; }
    //
    // Summary:
    //     Gets or sets a value indicating whether OldValue and NewValue is set.
    [NotMapped]
    public bool IsValueSet { get; set; }
    //
    // Summary:
    //     Gets or sets the name of the relation audited.
    [Column(Order = 2)]
    [MaxLength(255)]
    public string RelationName { get; set; }
    //
    // Summary:
    //     Gets or sets the name of the property audited.
    [Column(Order = 3)]
    [MaxLength(255)]
    public string PropertyName { get; set; }
    //
    // Summary:
    //     Gets or sets the parent.
    public AuditEntry Parent { get; set; }
    //
    // Summary:
    //     Gets or sets the identifier of the audit entry property.
    [Column(Order = 0)]
    public int AuditEntryPropertyID { get; set; }
    //
    // Summary:
    //     Gets or sets the new value audited formatted.
    [Column("NewValue", Order = 5)]
    public string NewValueFormatted { get; set; }
    //
    // Summary:
    //     Gets or sets the identifier of the audit entry.
    [Column(Order = 1)]
    public int AuditEntryID { get; set; }
    //
    // Summary:
    //     Gets or sets the old value audited formatted.
    [Column("OldValue", Order = 4)]
    public string OldValueFormatted { get; set; }
}

It looks good enough save for two properties: public List<AuditEntryProperty> Properties { get; set; } and public AuditEntry Parent { get; set; }. As they're not marked as virtual, adding a migration will fail. I tried an workaround just to see if I could get it to generate the tables and I was indeed successful (those lines commented earlier):

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        //...
        modelBuilder.Entity<AuditEntry>().Ignore(x => x.Properties);
        modelBuilder.Entity<AuditEntryProperty>().Ignore(x => x.Parent);
    }

That seems to disable the PrimaryKey-ForeignKey relationship both tables have, which are setup inside the framework itself, as there's no indication that I should do it manually. I even tried to run the script just to see what would come of it, and results were catastrophic:

CREATE INDEX [IX_AuditEntryID] ON [dbo].[AuditEntryProperties]([AuditEntryID])

GO

ALTER TABLE [dbo].[AuditEntryProperties] 
ADD CONSTRAINT [FK_dbo.AuditEntryProperties_dbo.AuditEntries_AuditEntryID] 
FOREIGN KEY ([AuditEntryID])
REFERENCES [dbo].[AuditEntries] ([AuditEntryID])
ON DELETE CASCADE

GO

That got me the following SQL error upon insertion: String or binary data would be truncated. So I just rolled back to the previous state, where the framework has a "50% output", as it saves records to the AuditEntry table (which holds data such as the table) whenever a user requests an insert, update or delete operations but nothing will be persisted in the AuditEntryProperties (new value, old value, column) and I can't think of anything else other than those properties being ignored to be the cause of all of this.

I thought I may override both AuditEntry and AuditEntryProperties, but that sounds like a big, stupid workaround. I'm no DB expert, what am I missing here?

Edit: Forgot to add the migration code:

        migrationBuilder.CreateTable(
            name: "AuditEntries",
            columns: table => new
            {
                AuditEntryID = table.Column<int>(nullable: false)
                    .Annotation("SqlServer:Identity", "1, 1"),
                CreatedBy = table.Column<string>(maxLength: 255, nullable: true),
                CreatedDate = table.Column<DateTime>(nullable: false),
                EntitySetName = table.Column<string>(maxLength: 255, nullable: true),
                EntityTypeName = table.Column<string>(maxLength: 255, nullable: true),
                State = table.Column<int>(nullable: false),
                StateName = table.Column<string>(maxLength: 255, nullable: true)
            },
            constraints: table =>
            {
                table.PrimaryKey("PK_AuditEntries", x => x.AuditEntryID);
            });

        migrationBuilder.CreateTable(
            name: "AuditEntryProperties",
            columns: table => new
            {
                AuditEntryPropertyID = table.Column<int>(nullable: false)
                    .Annotation("SqlServer:Identity", "1, 1"),
                AuditEntryID = table.Column<int>(nullable: false),
                PropertyName = table.Column<string>(maxLength: 255, nullable: true),
                RelationName = table.Column<string>(maxLength: 255, nullable: true),
                NewValue = table.Column<string>(nullable: true),
                OldValue = table.Column<string>(nullable: true)
            },
            constraints: table =>
            {
                table.PrimaryKey("PK_AuditEntryProperties", x => x.AuditEntryPropertyID);
            });

Edit 2 Tried to add the FK with Fluent API:

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.ApplyConfigurationsFromAssembly(typeof(CadastralDbContext).Assembly);
        modelBuilder.Entity<AuditEntryProperty>().HasOne<AuditEntry>(prop => prop.Parent).WithMany(a => a.Properties).HasForeignKey(prop => prop.AuditEntryID);
    }

Migration still cannot be performed as those properties are not virtual.

1
0
11/5/2019 6:44:40 PM

Accepted Answer

We created an issue on the EF Plus Issues Tracker

You will find here a project that you could try, I suggest you continue the discussion on our Issue Tracker since Stack Overflow is not a platform for this kind of issue.

1
11/6/2019 3:42:21 PM


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