Undelete Request Handler

The UndeleteRequestHandler is the base class that handles Undelete service requests. It restores a record that was previously soft deleted.

Sergen only generates an Undelete handler for rows that support soft delete, i.e. rows implementing IIsActiveDeletedRow or IIsDeletedRow. For a row without an IsActive/IsDeleted field (which is hard-deleted), there is nothing to undelete, so no handler is generated.

Generated Handler

For a row that supports soft delete, Sergen generates:

using MyRow = MyProject.Administration.UserRow;

namespace MyProject.Administration;

public interface IUserUndeleteHandler : IUndeleteHandler<MyRow> { }

public class UserUndeleteHandler(IRequestContext context)
    : UndeleteRequestHandler<MyRow>(context), IUserUndeleteHandler
{
}

The class derives from the generic UndeleteRequestHandler<TRow> and IUndeleteRequestHandler.

The Service Endpoint

The endpoint exposes a single Undelete action:

[Route("Services/Administration/User/[action]")]
[ConnectionKey(typeof(MyRow)), ServiceAuthorize(typeof(MyRow))]
public class UserEndpoint : ServiceEndpoint
{
    [HttpPost, AuthorizeDelete(typeof(MyRow))]
    public UndeleteResponse Undelete(IUnitOfWork uow, UndeleteRequest request,
        [FromServices] IUserUndeleteHandler handler)
    {
        return handler.Undelete(uow, request);
    }
}

The Request and Response

The request is an UndeleteRequest:

public class UndeleteRequest : ServiceRequest
{
    public object EntityId { get; set; }
}

It only contains the ID of the record to restore. The response is an UndeleteResponse:

public class UndeleteResponse : ServiceResponse
{
    public bool WasNotDeleted { get; set; }
}

WasNotDeleted is true if the record was not actually soft-deleted (e.g. it was already restored, or its IsActive was not -1).

What Undelete Does

Depending on the row type:

For IIsActiveDeletedRow rows, the handler issues UPDATE ... SET IsActive = 1 where IsActive = -1, restoring the record to active.
For IIsDeletedRow rows, it sets IsDeleted = false.

If the row type doesn't implement one of these interfaces, the handler raises an error, because there is no way to undelete a hard-deleted record.

Lifecycle Methods

The main overridable methods are:

OnBeforeUndelete() — called before the undelete is executed.
OnAfterUndelete() — called after the undelete succeeds.
OnReturn() — called just before the response is returned.

OnBeforeUndelete/OnAfterUndelete also invoke any registered IUndeleteBehavior.OnBeforeUndelete / OnAfterUndelete.