WPF: MVVM and editing hierarchical data

Question

I'm still trying to wrap my head around MVVM. Let's say I have a model that looks something like this:

public class Company { public IList<Division> Divisions { get;set;} } public class Division { public string Name { get;set;} public IList<Department> Departments { get;set} } public class Department { public string UnitNumber { get;set;} public string DepartmentName { get;set;} public IList<Employee> Employees { get;set;} } public class Employee { public string FirstName { get;set;} public string LastName { get;set;} public string JobTitle { get;set;} } 

Now let me say that I want to display the hierarchy of companies in a hierarchical grid, I create the CompanyViewModel class below:

 public class CompanyViewModel : INotifyPropertyChanged { private Company _company; public Company Company { get { return _company;} set { _company = value; NotifyPropertyChanged("Company");} } } 

Now, in my view (WPF), I set the data context in the ViewModel, and the selected dataset would snap to the Company path. Everything is wonderful so far ... I get a nice extension / smoothing interface in Divions, departments, employees ...

Besides:

• What if the grid is editable ... Department names must be changed (and checked by ViewModel, same for Employee names ..

• What if I want to add new employees, departments, etc., all this should be reflected in the grid without overwriting (what is the WPF data anchor point right?)

Potential solution:

You have a separate ViewModel class for each domain class ...

This, apparently, means a lot from displaying DTO → ViewModel, duplication (because they are almost the same objects and yet not quite.) Given that I'm probably already mapped to some kind of ORM → DTO on object the service side, sending it through the wiring (WCF) to the client, matching each DTO hierarchy into its own ViewModel is a difficult and expensive process (not to mention the work associated with this).

Bleeding such as INotifyPropertyChanged, ObservableCollection, etc. in my DTO seem to be hacked.

Does anyone have a better solution? I'm crazy?; -)

Answer 1

"Bleeding such as INotifyPropertyChanged, ObservableCollection, etc. in my DTOs seem to be a hack."

I feel your pain, but this is the approach I have taken on several projects.

Bottom line: in order to bind WPF data to “work”, as advertised objects / collections that you bind, you need to support INotifyPropertyChanged and ObservableCollection.

Personally, I think that creating a DTO that supports this is a lot less work than constantly moving the data back and forth to a viewmodel or other intermediate object, which is essentially a richer version of the DTO object.

Answer 2

If you don't like entering code for INotifyPropertyChanged, and you also use automatic properties, why not take a look at MoXAML Power Toys , which allows you to convert automatic properties to recognizable?