[英]TwoWay Binding on Windows Phone 8.1 app, using MVVM
我正在使用MVVM開發銷售管理系統,但是我在保存視圖中輸入的數據方面存在問題。 我假設TwoWay Binding意味着在視圖上輸入的所有值都應傳遞給ViewModel,反之亦然,我是對的嗎?
查看 :
<TextBox x:Name="NameText"
Grid.ColumnSpan="2"
Grid.Row="2"
Header="Nombre:"
Style="{StaticResource RegisterTextBoxStyle}"
Text="{Binding Product.Name, Mode=TwoWay}"/>
<ComboBox x:Name="UnitCombo"
Grid.Row="3"
Grid.ColumnSpan="2"
Header="Unidad:"
PlaceholderText="Elige la medida"
Style="{StaticResource RegisterComboBoxStyle}"
ItemsSource="{Binding Path=UnitsSource, Mode=OneWay}"
SelectedValue="{Binding SelectedUnit, Mode=TwoWay}"/>
<TextBox x:Name="CostText"
Grid.Column="0"
Grid.Row="4"
Header="Costo:"
Style="{StaticResource RegisterTextBoxStyle}"
Text="{Binding Product.Cost, Mode=TwoWay}"/>
<TextBox x:Name="PriceText"
Grid.Column="1"
Grid.Row="4"
Header="Precio:"
Style="{StaticResource RegisterTextBoxStyle}"
Text="{Binding Product.Price, Mode=TwoWay}"/>
<ToggleSwitch x:Name="ActiveToggle"
Grid.Column="1"
Grid.Row="5"
Style="{StaticResource RegisterToggleSwithStyle}"
IsOn="{Binding Product.Active, Mode=TwoWay}"/>
View使用SaveProduct命令保存在視圖上輸入的所有值,並從以下位置調用:
<AppBarButton Icon="Accept" Label="Añadir" Command="{Binding Path=SaveCommand}"/>
我在codebehind上建立了DataContext :
public AddProduct()
{
InitializeComponent();
DataContext = new ProductListViewModel();
}
ProductListViewModel :
namespace BillingShop.ViewModel
{
public class ProductListViewModel : ViewModelBase, INavigable
{
public ObservableCollection<ProductViewModel> Items { get; private set; }
private DelegateCommand _saveProduct;
public bool IsUpdating { get; set; }
public ProductViewModel Product { get; set; }
public Visibility UpdatingVisibility => (IsUpdating || Items == null || Items.Count == 0) ? Visibility.Visible : Visibility.Collapsed;
public ProductListViewModel()
{
if (IsInDesignMode)
{
return;
}
_saveProduct = new DelegateCommand(SaveCommand_Executed);
}
#region Product Members
private string _unit;
public string SelectedUnit
{
get { return _unit; }
set
{
_unit = value;
OnPropertyChanged();
}
}
#endregion
public IEnumerable<RegisteredUnits> UnitsSource => Enum.GetValues(typeof(RegisteredUnits)).Cast<RegisteredUnits>();
public ICommand SaveCommand => _saveProduct;
private void SaveCommand_Executed()
{
var product = new Product
{
Name = Product.Name,
Unit = Product.Unit,
Cost = Convert.ToDouble(Product.Cost),
Price = Convert.ToDouble(Product.Price),
Active = Convert.ToBoolean(Product.Active)
};
ProductManager.SaveProduct(product);
}
public void PopulateProductViewModel(ProductViewModel entry)
{
Product = entry;
OnPropertyChanged("Product");
}
public Product GetProduct()
{
return Product?.GetProduct();
}
}
}
ProductViewModel :
public class ProductViewModel : ViewModelBase
{
public int Id { get; set; }
public string Name { get; set; }
public string Unit { get; set; }
public double Cost { get; set; }
public double Price { get; set; }
public bool Active { get; set; }
public List<SalesDetails> SalesDetail { get; set; }
public ProductViewModel()
{
}
public ProductViewModel(Product item)
{
Update(item);
}
public void Update (Product item)
{
Id = item.ID;
Name = item.Name;
Unit = item.Unit;
Cost = item.Cost;
Price = item.Price;
Active = item.Active;
SalesDetail = item.SalesDetail;
}
public Product GetProduct()
{
return new Product
{
ID = Id,
Name = Name,
Unit = Unit,
Cost = Cost,
Price = Price,
Active = Active,
SalesDetail = SalesDetail
};
}
}
執行SaveProduct時 , Product類顯示為null,我的視圖值如何? 我的代碼出了什么問題?
感謝所有幫助我的人,我在這里放置我的存儲庫鏈接,也許有人想深入了解我的代碼: https : //github.com/adoibarra/BillingShop
編輯 :這是我的產品類 :
public class Product : IBusinessEntity
{
/// <summary>
/// Represents a Product.
/// </summary>
public Product()
{
}
/// <summary>
/// Get or sets the product identifier.
/// </summary>
[PrimaryKey, AutoIncrement]
public int ID { get; set; }
/// <summary>
/// Get or sets the product name.
/// </summary>
[MaxLength(40)]
public string Name { get; set; }
/// <summary>
/// Get or sets if the product can be measured in units or kilograms.
/// </summary>
public string Unit { get; set; }
/// <summary>
/// Get or sets the product cost.
/// </summary>
public double Cost { get; set; }
/// <summary>
/// Get or sets the product price.
/// </summary>
public double Price { get; set; }
/// <summary>
/// Get or sets the product state.
/// </summary>
public bool Active { get; set; }
/// <summary>
/// One-To-Many relationship with SalesDetails.
/// </summary>
[OneToMany(CascadeOperations = CascadeOperation.All)]
public List<SalesDetails> SalesDetail { get; set; }
}
解決方案是在ProductListViewModel構造函數中初始化Product屬性:
public class ProductListViewModel
{
public ProductListViewModel ()
{
Product = new ProductViewModel();
}
.
.
.
}
感謝Weimar Yamit Moreno Perez的幫助,以及Archana的干預。
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