I am now developing a product, which will use Unity & Repositories when it comes to data management. I will demonstrate on a simple example. What we want to do, is to create an app with calendar control, where user (e.g. manager) will be able to store holidays for his employees.
First define our models:
We have a class Employee which looks like following:
public class Employee :ViewModelBase, IEditableObject
{
public int EmployeeID { get; set; }
public string FullName
{
get
{
return $"{this.Name} {this.Surname}";
}
}
private string _Name;
public string Name
{
get { return _Name; }
set
{
_Name = value;
OnPropertyChanged("Name");
}
}
private string _Surname;
public string Surname
{
get { return _Surname; }
set
{
_Surname = value;
OnPropertyChanged("Surname");
}
}
private DateTime _DateOfBirth;
public DateTime DateOfBirth
{
get
{
if (_DateOfBirth == DateTime.MinValue)
_DateOfBirth = DateTime.Now;
return _DateOfBirth;
}
set
{
_DateOfBirth = value;
OnPropertyChanged("DateOfBirth");
}
}
//hierachy level
private int _EmployeeLevelID;
public int EmployeeLevelID
{
get { return _EmployeeLevelID; }
set
{
_EmployeeLevelID = value;
OnPropertyChanged("EmployeeLevelID");
}
}
private ObservableCollection<Holidays> _Holidays;
public ObservableCollection<Holidays> Holidays
{
get
{
if (_Holidays == null)
_Holidays = new ObservableCollection<Shared.Holidays>();
return _Holidays;
}
set
{
_Holidays = value;
OnPropertyChanged("Holidays");
}
}
}
public class Holidays : ViewModelBase, ICloneable
{
public DateTime Start { get; set; }
public DateTime End { get; set; }
public string Reason { get; set; }//Holiday, Sick Leave, ...
public string Description { get; set; }
public string UniqueID { get; set; }
public object Clone()
{
var item = new Holidays();
item.Start = this.Start;
item.End = this.End;
item.Reason = this.Reason;
item.Description = this.Description;
return item;
}
}
Every Employee has a list of his own "Holidays" (days, when he is not working either because of holidays, or sickness, or any other reason).
Then we have another model for Appointment, which is used under our calendar control. It's quite complex, but here is just a glimpse of it:
public abstract class AppointmentBase
{
protected AppointmentBase();
public virtual ICategory Category { get; set; }
public virtual DateTime End { get; set; }
public virtual Importance Importance { get; set; }
public virtual bool IsAllDayEvent { get; set; }
public virtual IRecurrenceRule RecurrenceRule { get; set; }
public virtual ResourceCollection Resources { get; }
public virtual DateTime Start { get; set; }
public virtual string Subject { get; set; }
public virtual ITimeMarker TimeMarker { get; set; }
public virtual TimeZoneInfo TimeZone { get; set; }
public event EventHandler RecurrenceRuleChanged;
public override void CopyFrom(IAppointment other);
public bool Equals(IAppointment other);
protected virtual void OnRecurrenceRuleChanged(EventArgs args);
}
Here is how our repository could look like:
public class EmployeeRepository : Interfaces.Repository.IEmployeeRepository
{
#region Repositories
private readonly ObservableCollection<Employee> repository_Employees;
#endregion
private readonly IDataManager _EmployeeManager;
public EmployeeRepository(IDataManager EmployeeManager)
{
_EmployeeManager = EmployeeManager;
repository_Employees = _EmployeeManager.LoadEmployees();
}
public ObservableCollection<Employee> ReturnEmployees()
{
return new ObservableCollection<Employee>(repository_Employees);
}
public void SaveEmployee(Employee person)
{
if (repository_Employees.Any(n => n.EmployeeID == person.EmployeeID))
{
//person exists
var existingPerson = repository_Employees.FirstOrDefault(n => n.EmployeeID == person.EmployeeID);
existingPerson = person;
}
else
{
//person does not exist
repository_Employees.Add(person);
}
SaveEmployees();
}
public void RemoveEmployee(Employee person)
{
//check if ID has already been added to the database
if (repository_Employees.Any(n => n.EmployeeID == person.EmployeeID))
repository_Employees.Remove(repository_Employees.First(n => n.EmployeeID == person.EmployeeID));
SaveEmployees();
}
public void SaveEmployees()
{
_EmployeeManager.SaveEmployees(repository_Employees);
}
public int GetNextEmployeeID()
{
if (repository_Employees.Count == 0)
return 1;
else
return repository_Employees.Max(n => n.EmployeeID) + 1;
}
}
And finally we have a model which loads & saves our data from Repository to Database. Here is how interface would look like:
public interface IDataManager
{
ObservableCollection<Employee> LoadEmployees();
void SaveEmployees(ObservableCollection<Employee> employees);
void DeleteEmployee(Employee person);
ObservableCollection<EmployeeLevel> LoadEmployeeLevel();
void SaveEmployeeLevels(ObservableCollection<EmployeeLevel> levels);
void DeleteEmployeeLevel(EmployeeLevel level);
}
Here comes the tricky part I am not quite sure about. Remember, that we are using a Calendar control, which expects Appointment class. Due to it's complexity (Calendar control is taken from Telerik) I have decided to create a small class Holidays that is present under each employee only with the necessary information (I don't need most of those things that are already implemented under that class).
Due to that, when I load & close my ViewModel, what I need to do is to convert my values to a corresponding model before I can actually save them.
I would like to know the following:
- Is this a good way how to implement repository in my application?
- Is it a good practice to do conversion the way I have presented?
I am open to any suggestions & comments as I am still learning repository patterns.
