綁定了ObservableCollection的dataGrid中的計算列

Question

我正在構建WPF-MVVM應用程序。 我有一個與ObservableCollection綁定的dataGrid。

在此集合中，我有一列“數量”，一列“價格/最小起訂量”和一列“合計”，在邏輯上必須等於“數量*價格=合計”。

因此，每次我添加一行並填充“數量和價格”時，都必須計算“總計”列。

我怎樣才能做到這一點？

視圖

    <DataGrid x:Name="dataGridInvoice" Margin="5" Grid.Row="1" 
                          ItemsSource="{Binding Collection}" 
                          AutoGenerateColumns="False"
                          SelectedItem="{Binding Selected, Mode=TwoWay}" 
                          SelectionMode="Extended" SelectionUnit="FullRow" AddingNewItem="dataGridInvoice_AddingNewItem">
                    <DataGrid.Columns>
                        <DataGridTextColumn Header="SuppNb" Binding="{Binding suppInvNumber, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Width="*"/>
                        <DataGridTextColumn Header="Shop" Binding="{Binding shop, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Width="*"/>
                        <DataGridTextColumn Header="Date" Binding="{Binding date, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Width="*"/>
                        <DataGridTextColumn Header="Supplier" Binding="{Binding supplier, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Width="*"/>
                        <DataGridComboBoxColumn Header="Ref Supplier"
                                                    ItemsSource="{Binding Products, Mode=OneWay, Source={StaticResource supplier}}"
                                                    DisplayMemberPath="refsup" 
                                                    SelectedValueBinding="{Binding refSupp}" 
                                                    SelectedValuePath="refsup"
                                                    Width="*"/>
                        <DataGridTextColumn Header="Description" Binding="{Binding description, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Width="*"/>
                        <DataGridComboBoxColumn Header="Unit"
                                                    ItemsSource="{Binding Collection, Mode=OneWay, Source={StaticResource unit}}"
                                                    DisplayMemberPath="unit1" 
                                                    SelectedValueBinding="{Binding unit}" 
                                                    SelectedValuePath="idunit"
                                                    Width="*"/>
                        <DataGridTextColumn Header="Quantity" Binding="{Binding quantity, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Width="*"/>
                        <DataGridTextColumn Header="Prix/MOQ" Binding="{Binding unitPrice, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Width="*"/>
                        <DataGridTextColumn Header="Total Price" Binding="{Binding totalPrice, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Width="*"/>
                    </DataGrid.Columns>
</DataGrid>

視圖模型

public class InvoiceViewModel : ViewModelBase
{
    public Context ctx = new Context();
    public InvoiceViewModel()
    {
        Get(false);
    }

    private ObservableCollection<Invoice> collection;
    public ObservableCollection<Invoice> Collection
    {
        get
        {
            return collection;
        }
        set
        {
            collection = value;
            OnPropertyChanged("Collection");
        }
    }

    private Invoice _selected;
    public Invoice Selected
    {
        get
        {
            return _selected;
        }
        set
        {
            _selected = value;
            OnPropertyChanged("Selected");
        }
    }

    private void Get(bool loadDataFirst)
    {
        if(loadDataFirst)
            ctx.Invoices.Load();
        Collection = ctx.Invoices.Local;
    }

    private void Save()
    {
        ctx.SaveChanges();
    }

    private void Delete()
    {
        var id = Selected;
        var invoice = (from i in ctx.Invoices
                       where i.idInvoice == id.idInvoice
                       select i).SingleOrDefault();
        Collection.Remove(invoice);
    }

    private Invoice _currentItem;
    public Invoice CurrentItem
    {
        get
        {
            return _currentItem;
        }
        set
        {
            _currentItem = value;
            OnPropertyChanged("CurrentItem");
        }
    }

    #region "Command"

    private ICommand saveCommand;
    private ICommand removeCommand;

    public ICommand SaveCommand
    {
        get
        {
            return saveCommand ?? (saveCommand = new RelayCommand(p => this.Save(), p => this.CanSave()));
        }
    }
    private bool CanSave()
    {
        return true;
    }
    #endregion
}

模型

public partial class Invoice
    {
        public int idInvoice { get; set; }
        public string invNumber { get; set; }
        public string suppInvNumber { get; set; }
        public Nullable<int> supplier { get; set; }
        public Nullable<int> shop { get; set; }
        public Nullable<System.DateTime> date { get; set; }
        public string refSupp { get; set; }
        public string description { get; set; }
        public string unit { get; set; }
        public Nullable<decimal> quantity { get; set; }
        public Nullable<decimal> unitPrice { get; set; }
        public Nullable<decimal> totalPrice { get; set; }

        public virtual foodSupplier foodSupplier { get; set; }
        public virtual shop shop1 { get; set; }
    }

Answer 1

坎蒂努，

我看到兩種方式：

1. 更改發票類，使其引發事件

   公共部分類發票：ViewModelBase {// .... private可空數量；

    public Nullable<decimal> Quantity { get { return quantity; } set { quantity = value; base.OnPropertyChanged(); if (quantity.HasValue && unitPrice.HasValue) TotalPrice = quantity * unitPrice; } } private Nullable<decimal> unitPrice; public Nullable<decimal> UnitPrice { get { return unitPrice; } set { unitPrice = value; base.OnPropertyChanged(); if (quantity.HasValue && unitPrice.HasValue) TotalPrice = quantity * unitPrice; } } private Nullable<decimal> totalPrice; public Nullable<decimal> TotalPrice { get { return totalPrice; } set { totalPrice = value; base.OnPropertyChanged(); } } 

   }

2. 在您的GUI中放入一些代碼以檢測版本結束並生產產品。 我認為這不是計算價格的責任，但是從技術上講，這是可能的。

    private void DataGridInvoiceRowEditEnding(object sender, DataGridRowEditEndingEventArgs e) { if (e.EditAction == DataGridEditAction.Commit) { Invoice invoice = e.Row.DataContext as Invoice; // update Invoice object if needed if (invoice != null) { // .... } } } private void DataGridInvoiceCellEditEnding(object sender, DataGridCellEditEndingEventArgs e) { // ... } 

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