Polecat Metadata

Polecat can automatically track metadata on your documents through several built-in interfaces.

ITracked

Implement ITracked to have correlation, causation, and user tracking automatically synced:

public class Order : ITracked
{
    public Guid Id { get; set; }
    public string Description { get; set; } = "";

    // ITracked members - auto-synced from session
    public string? CorrelationId { get; set; }
    public string? CausationId { get; set; }
    public string? LastModifiedBy { get; set; }
}

Set tracking values on the session:

await using var session = store.LightweightSession(new SessionOptions
{
    CorrelationId = "request-123",
    CausationId = "command-456",
    LastModifiedBy = "user@example.com"
});

session.Store(new Order { Description = "New order" });
await session.SaveChangesAsync();
// Order.CorrelationId will be "request-123"

ITenanted

Implement ITenanted to have the tenant ID automatically synced from the session:

public class Order : ITenanted
{
    public Guid Id { get; set; }
    public string TenantId { get; set; } = "";
}

See Multi-Tenancy for more details.

ISoftDeleted

Implement ISoftDeleted for automatic soft delete tracking:

public class Order : ISoftDeleted
{
    public Guid Id { get; set; }
    public bool Deleted { get; set; }
    public DateTimeOffset? DeletedAt { get; set; }
}

See Deleting Documents for more details.

IVersioned

Implement IVersioned for Guid-based optimistic concurrency:

public class Order : IVersioned
{
    public Guid Id { get; set; }
    public Guid Version { get; set; }
}

See Optimistic Concurrency for more details.

Mapping the version onto a member of your own

The version column can be mapped onto any member instead, and the member's type chooses the concurrency mode — Guid for Guid versioning, int or long for numeric revisions:

opts.Schema.For<Order>().Metadata(m => m.Version.MapTo(x => x.Etag));

[VersionMetadata] on the member is the same declaration. Either way the mapped member is a full concurrency declaration, not just a place to read the stored value: it is stamped on write, populated on load, and carries the expected version into the write's guard. See Optimistic Concurrency.

Built-in Metadata Columns

Every document table includes these metadata columns automatically:

Column	Description
last_modified	Updated to SYSDATETIMEOFFSET() on every save
created	Set to SYSDATETIMEOFFSET() on first insert
type	Short type discriminator
dotnet_type	Full .NET assembly-qualified type name

Metadata LINQ Extensions

Query documents by their metadata:

// Find documents modified since a given time
var recent = await session.Query<Order>()
    .Where(x => x.ModifiedSince(DateTimeOffset.UtcNow.AddHours(-1)))
    .ToListAsync();

// Find documents modified before a given time
var old = await session.Query<Order>()
    .Where(x => x.ModifiedBefore(DateTimeOffset.UtcNow.AddDays(-30)))
    .ToListAsync();