MVVM_ContactForm_WP_ViewModels

ContactPageViewModel.cs

public class ContactPageViewModel : INotifyPropertyChanged
{
    private readonly IContactRepository _contactRepository;

    private readonly IValidator _requiredFieldValidator;

    private ObservableCollection<Category> _categories;

    private string _email;

    private string _inquiry;

    private bool _isValid;

    private string _name;

    private Category _selectedCategory;

    public ContactPageViewModel()
    {
        this._requiredFieldValidator = new RequiredFieldValidator();
        this._contactRepository = new ContactRepository();
        this.SubmitCommand = new RelayCommand(this.OnSubmit);
    }

    public event PropertyChangedEventHandler PropertyChanged;

    public ObservableCollection<Category> Categories
    {
        get
        {
            return this._categories;
        }

        set
        {
            this._categories = value;
            this.OnPropertyChanged();
        }
    }

    public string Email
    {
        get
        {
            return this._email;
        }

        set
        {
            this._email = value;
            this.OnPropertyChanged();
        }
    }

    public string Inquiry
    {
        get
        {
            return this._inquiry;
        }

        set
        {
            this._inquiry = value;
            this.OnPropertyChanged();
        }
    }

    public bool IsValid
    {
        get
        {
            return this._isValid;
        }

        set
        {
            this._isValid = value;
            this.OnPropertyChanged();
        }
    }

    public string Name
    {
        get
        {
            return this._name;
        }

        set
        {
            this._name = value;
            this.OnPropertyChanged();
        }
    }

    public Category SelectedCategory
    {
        get
        {
            return this._selectedCategory;
        }

        set
        {
            this._selectedCategory = value;
            this.OnPropertyChanged();
        }
    }

    public ICommand SubmitCommand { get; set; }

    public void InitializeViewModel()
    {
        this.Name = string.Empty;
        this.Email = string.Empty;
        this.Categories = new ObservableCollection<Category>(
            this._contactRepository.PopulateDummyDataInCategories());
        this._requiredFieldValidator.RegisterPropertyChangeForValidation(this);
    }

    protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        var eventHandler = this.PropertyChanged;
        if (eventHandler != null)
        {
            eventHandler(this, new PropertyChangedEventArgs(propertyName));
        }
    }

    private void OnSubmit()
    {
        this._contactRepository.Submit(this.Name, this.Email, this.SelectedCategory.Id, this.Inquiry);
    }
}