abp-entity-patterns

{ public string FirstName { get ; private set ; } public string LastName { get ; private set ; } public string Email { get ; private set ; } public DateTime DateOfBirth { get ; private set ; } public bool IsActive { get ; private set ; } // Required for EF Core protected Patient ( ) { } // Constructor with validation public Patient ( Guid id , string firstName , string lastName , string email , DateTime dateOfBirth ) : base ( id ) { SetName ( firstName , lastName ) ; SetEmail ( email ) ; DateOfBirth = dateOfBirth ; IsActive = true ; } // Domain methods with validation public void SetName ( string firstName , string lastName ) { FirstName = Check . NotNullOrWhiteSpace ( firstName , nameof ( firstName ) , maxLength : 100 ) ; LastName = Check . NotNullOrWhiteSpace ( lastName , nameof ( lastName ) , maxLength : 100 ) ; } public void SetEmail ( string email ) { Email = Check . NotNullOrWhiteSpace ( email , nameof ( email ) , maxLength : 256 ) ; } public void Activate ( ) => IsActive = true ; public void Deactivate ( ) => IsActive = false ; } Soft Delete public class Patient : FullAuditedAggregateRoot < Guid

, ISoftDelete { public bool IsDeleted { get ; set ; } // ABP automatically filters out soft-deleted entities } Multi-Tenancy public class Patient : FullAuditedAggregateRoot < Guid

, IMultiTenant { public Guid ? TenantId { get ; set ; } // ABP automatically filters by current tenant } Audit Fields FullAuditedAggregateRoot provides: CreationTime , CreatorId LastModificationTime , LastModifierId IsDeleted , DeletionTime , DeleterId Repository Pattern Generic Repository Usage public class PatientAppService : ApplicationService { private readonly IRepository < Patient , Guid

_patientRepository ; public PatientAppService ( IRepository < Patient , Guid

patientRepository ) { _patientRepository = patientRepository ; } public async Task < PatientDto

GetAsync ( Guid id ) { var patient = await _patientRepository . GetAsync ( id ) ; return ObjectMapper . Map < Patient , PatientDto

( patient ) ; } public async Task < PagedResultDto < PatientDto

GetListAsync ( PagedAndSortedResultRequestDto input ) { var totalCount = await _patientRepository . GetCountAsync ( ) ; var queryable = await _patientRepository . GetQueryableAsync ( ) ; var patients = await AsyncExecuter . ToListAsync ( queryable . OrderBy ( input . Sorting ?? nameof ( Patient . FirstName ) ) . PageBy ( input . SkipCount , input . MaxResultCount ) ) ; return new PagedResultDto < PatientDto

( totalCount , ObjectMapper . Map < List < Patient

, List < PatientDto

( patients ) ) ; } } Custom Repository Define interface in Domain layer: public interface IPatientRepository : IRepository < Patient , Guid

{ Task < List < Patient

GetActivePatientsByDoctorAsync ( Guid doctorId ) ; Task < Patient ?

FindByEmailAsync ( string email ) ; } Implement in EntityFrameworkCore layer: public class PatientRepository : EfCoreRepository < ClinicDbContext , Patient , Guid

, IPatientRepository { public PatientRepository ( IDbContextProvider < ClinicDbContext

dbContextProvider ) : base ( dbContextProvider ) { } public async Task < List < Patient

GetActivePatientsByDoctorAsync ( Guid doctorId ) { var dbSet = await GetDbSetAsync ( ) ; return await dbSet . Where ( p => p . PrimaryDoctorId == doctorId && p . IsActive ) . Include ( p => p . Appointments ) . ToListAsync ( ) ; } public async Task < Patient ?

FindByEmailAsync ( string email ) { var dbSet = await GetDbSetAsync ( ) ; return await dbSet . FirstOrDefaultAsync ( p => p . Email == email ) ; } } Domain Services Use domain services when business logic involves multiple entities or external domain concepts. public class AppointmentManager : DomainService { private readonly IRepository < Appointment , Guid

_appointmentRepository ; private readonly IRepository < DoctorSchedule , Guid

_scheduleRepository ; public AppointmentManager ( IRepository < Appointment , Guid

appointmentRepository , IRepository < DoctorSchedule , Guid

scheduleRepository ) { _appointmentRepository = appointmentRepository ; _scheduleRepository = scheduleRepository ; } public async Task < Appointment

CreateAsync ( Guid patientId , Guid doctorId , DateTime appointmentDate , string description ) { // Business rule: Check if doctor is available await CheckDoctorAvailabilityAsync ( doctorId , appointmentDate ) ; // Business rule: Check for conflicts await CheckAppointmentConflictsAsync ( doctorId , appointmentDate ) ; var appointment = new Appointment ( GuidGenerator . Create ( ) , patientId , doctorId , appointmentDate , description ) ; return await _appointmentRepository . InsertAsync ( appointment ) ; } private async Task CheckDoctorAvailabilityAsync ( Guid doctorId , DateTime appointmentDate ) { var schedule = await _scheduleRepository . FirstOrDefaultAsync ( s => s . DoctorId == doctorId && s . DayOfWeek == appointmentDate . DayOfWeek ) ; if ( schedule == null ) throw new BusinessException ( "Doctor not available on this day" ) ; var timeOfDay = appointmentDate . TimeOfDay ; if ( timeOfDay < schedule . StartTime || timeOfDay

schedule . EndTime ) throw new BusinessException ( "Doctor not available at this time" ) ; } private async Task CheckAppointmentConflictsAsync ( Guid doctorId , DateTime appointmentDate ) { var hasConflict = await _appointmentRepository . AnyAsync ( a => a . DoctorId == doctorId && a . AppointmentDate == appointmentDate && a . Status != AppointmentStatus . Cancelled ) ; if ( hasConflict ) throw new BusinessException ( "Doctor already has an appointment at this time" ) ; } } Data Seeding IDataSeedContributor Pattern public class ClinicDataSeedContributor : IDataSeedContributor , ITransientDependency { private readonly IRepository < Doctor , Guid

_doctorRepository ; private readonly IGuidGenerator _guidGenerator ; public ClinicDataSeedContributor ( IRepository < Doctor , Guid

doctorRepository , IGuidGenerator guidGenerator ) { _doctorRepository = doctorRepository ; _guidGenerator = guidGenerator ; } public async Task SeedAsync ( DataSeedContext context ) { // Idempotent check if ( await _doctorRepository . GetCountAsync ( )

0 ) return ; var doctors = new List < Doctor

{ new Doctor ( _guidGenerator . Create ( ) , "Dr. Smith" , "Cardiology" , "smith@clinic.com" ) , new Doctor ( _guidGenerator . Create ( ) , "Dr. Jones" , "Pediatrics" , "jones@clinic.com" ) , } ; foreach ( var doctor in doctors ) { await _doctorRepository . InsertAsync ( doctor ) ; } } } Test Data Seeding public class ClinicTestDataSeedContributor : IDataSeedContributor , ITransientDependency { public static readonly Guid TestPatientId = Guid . Parse ( "2e701e62-0953-4dd3-910b-dc6cc93ccb0d" ) ; public static readonly Guid TestDoctorId = Guid . Parse ( "3a801f73-1064-5ee4-a21c-ed7dd4ddc1e" ) ; public async Task SeedAsync ( DataSeedContext context ) { await _patientRepository . InsertAsync ( new Patient ( TestPatientId , "Test" , "Patient" , "test@example.com" , DateTime . Now . AddYears ( - 30 ) ) ) ; await _doctorRepository . InsertAsync ( new Doctor ( TestDoctorId , "Test Doctor" , "General" , "doctor@example.com" ) ) ; } } Best Practices Encapsulate state - Use private setters and domain methods Validate in constructor - Ensure entity is always valid Use value objects - For complex properties (Address, Money) Domain logic in entity - Simple rules belong in the entity Domain service - For cross-entity logic Custom repository - Only when you need custom queries Idempotent seeding - Always check before inserting