從組合框中選擇專案時過濾資料時出現問題WPFMVVM-有解無憂

我在兩個不同的 tabitems 中有兩個資料網格。第一個 tabitem 中的資料網格顯示了一些關于應用程式加載的特定資料，如果資料發生變化，應該會更新，非常簡單。第二個 tabitem 的 datagrid 在應用程式加載時應該是空的，但是當從組合框中選擇/鍵入一個專案時，它應該根據該組合框所選專案過濾資料并顯示在第二個 tabitem 的 datagrid 上的過濾資料上（維護 MVVM 模式）。

這是我嘗試過的：

XAML

<TabControl>
    <TabItem Header="Pending Bills">
        <DataGrid ItemsSource="{Binding FilteredBills}" AutoGenerateColumns="False" CanUserAddRows="False">
            <DataGrid.Columns>
                <DataGridTextColumn
                        Header="Vendor"
                        Binding="{Binding Path=Party, Mode=OneWay}"
                        Width="275"
                        IsReadOnly="True" />
                <DataGridTextColumn
                        Header="Bill No."
                        Binding="{Binding Path=BillNo, Mode=OneWay}"
                        Width="275"
                        IsReadOnly="True" />
                ......
            </DataGrid.Columns>
        </DataGrid>
    </TabItem>
    <TabItem Header="Filtered Bills">
    ........
            <DataGrid Grid.Row="0" ItemsSource="{Binding AllBills}" AutoGenerateColumns="False" CanUserAddRows="False">
                <DataGrid.Columns>
                    <DataGridTextColumn
                        Header="Vendor"
                        Binding="{Binding Path=Party, Mode=OneWay}"
                        Width="275"
                        IsReadOnly="True" />
                    <DataGridTextColumn
                        Header="Bill No."
                        Binding="{Binding Path=BillNo, Mode=OneWay}"
                        Width="275"
                        IsReadOnly="True" />
                    ......
                </DataGrid.Columns>
            </DataGrid>
            <StackPanel Orientation="Horizontal">
                <ComboBox x:Name="cmbBox" ItemsSource="{Binding ComboItems}" SelectedItem="{Binding SelectedCBItem}"/>
            </StackPanel>
        </Grid>
    </TabItem>
</TabControl>

一個基礎視圖模型，以啟用PropertyChangedEventHandler

public class ViewModelBase : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    protected void OnPropertyChanged(string propertyName)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}

基本型號：

public class Bills : ViewModelBase
{
    private int _id;
    public int Id
    {
        get
        {
            return _id;
        }
        set
        {
            _id = value;
            OnPropertyChanged("Id");
        }
    }

    private string _party;
    public string Party
    {
        get
        {
            return _party;
        }
        set
        {
            _party = value;
            OnPropertyChanged("Party");
        }
    }

    private string _billNo;
    public string BillNo
    {
        get
        {
            return _billNo;
        }
        set
        {
            _billNo = value;
            OnPropertyChanged("BillNo");
        }
    }

    .......

}

billsviewmodel 和一個名為 Model 的輔助資料訪問類：

public class BillsViewModel : ViewModelBase
    {

        public BillsViewModel()
        {
            cvsAll.Source = m.AllBills;
            cvsFiltered.Source = m.FilteredBills;
        }

        Model m = new Model();

        CollectionViewSource cvsAll = new CollectionViewSource();
        public ICollectionView AllBills
        {
            get { return cvsAll.View; }
        }


        public List<string> ComboItems
        {
            get { return m.UniqueValues(); }
        }

        CollectionViewSource cvsFiltered = new CollectionViewSource();
        public ICollectionView FilteredBills
        {
            get { return cvsFiltered.View; }
        }


        private string _selectedCBItem;
        public string SelectedCBItem
        {
            get { return _selectedCBItem; }
            set
            {
                _selectedCBItem = value;
                cvsFiltered.Source = m.GetBills_Pen(value);
                OnPropertyChanged("SelectedCBItem");
            }
        }
    }

    public class Model
    {
        private List<Bills> _allBills;

        public List<Bills> AllBills
        {
            get
            {
                if (_allBills == null) LoadAllBillsFromDatabase();
                
                return _allBills;
            }
        }

        private List<Bills> _filteredBills;

        public List<Bills> FilteredBills
        {
            get
            {
                if (_filteredBills == null) LoadUnpaidBillsFromDatabase();

                return _filteredBills;
            }
        }

        public void LoadAllBillsFromDatabase()
        {
            SQLiteConnection m_dbConnection = new SQLiteConnection(@"Data Source=Bills.db;");
            SQLiteCommand sqlCom = new SQLiteCommand(@"Select * From billdata", m_dbConnection);
            SQLiteDataAdapter sda = new SQLiteDataAdapter(sqlCom);
            DataTable dt = new DataTable();
            sda.Fill(dt);
            _allBills = new List<Bills>();
            
            foreach (DataRow row in dt.Rows)
            {
                _allBills.Add(new Bills()
                {
                    Id = Convert.ToInt32(row["Id"]),
                    Party = (string)row["Party"],
                    BillNo = (string)row["BillNo"],
                    .......
                });
                
            }
            m_dbConnection.Close();
        }

        public void LoadUnpaidBillsFromDatabase()
        {
            SQLiteConnection m_dbConnection = new SQLiteConnection(@"Data Source=Bills.db;");
            SQLiteCommand sqlCom = new SQLiteCommand(@"Select * From billdata where PaidOn != ''", m_dbConnection);
            SQLiteDataAdapter sda = new SQLiteDataAdapter(sqlCom);
            DataTable dt = new DataTable();
            sda.Fill(dt);
            _filteredBills = new List<Bills>();

            foreach (DataRow row in dt.Rows)
            {
                _filteredBills.Add(new Bills()
                {
                    Id = Convert.ToInt32(row["Id"]),
                    Party = (string)row["Party"],
                    BillNo = (string)row["BillNo"],
                    .......
                });

            }
            m_dbConnection.Close();
        }

        public List<string> UniqueValues()
        {
            return _allBills.Select((s) => s.Party).Distinct().OrderBy((s) => s).ToList();
        }
         

        public List<Bills> GetBills_Pen(string filterValue)
        { 
            return _allBills.FindAll(s => s.Party == filterValue).ToList();
        }
    }

有2個問題：

第二個 tabitem 上的資料網格正在顯示應用程式加載的所有資料
當我在組合框中選擇或鍵入有效專案時，第二個 tabitem 上的資料網格未顯示過濾后的資料。

我沒有ICollectionView以正確的方式實施或者我在這里做錯了什么，最重要的是我該如何解決這個問題？

uj5u.com熱心網友回復：

這應該有效。我還向 ViewModelBase 添加了一個函式以使代碼更短

public class ViewModelBase
{
    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        var handler = PropertyChanged;
        if (handler != null)
            handler(this, new PropertyChangedEventArgs(propertyName));
    }
    protected virtual void SetValue<T>(ref T field, T value, [CallerMemberName] string propertyName = null)
    {
        field = value;
        OnPropertyChanged(propertyName);
    }
}

public class BillsViewModel : ViewModelBase
{
    private List<BillViewModel> _allBills;

    public BillsViewModel()
    {
        _allBills = m.AllBills;
        AllBills = new ListCollectionView(_allBills);
        ComboItems = _allBills.Select(b => b.Party).Distinct().OrderBy(b => b).ToList();
        FilteredBills = new ListCollectionView(_allBills)
        {
            Filter = o => ((BillViewModel)o).Party == SelectedCBItem
        };
    }

    Model m = new Model();

    public ICollectionView AllBills { get; private set; }
    public ICollectionView FilteredBills { get; private set; }

    public List<string> ComboItems { get; private set; }

    private string _selectedCBItem;
    public string SelectedCBItem
    {
        get { return _selectedCBItem; }
        set
        {
            SetValue(ref _selectedCBItem, value);
            FilteredBills.Refresh();
        }
    }
}

uj5u.com熱心網友回復：

第二個 tabitem 上的資料網格正在顯示應用程式加載的所有資料

那是因為您將AllBills視圖模型的屬性的源設定為AllBills包含（？）所有專案的模型的屬性。如果您希望它為空，則不要將其設定為Source包含任何專案的串列：

public BillsViewModel()
{
    cvsFiltered.Source = m.FilteredBills;
}

當我在組合框中選擇或鍵入有效專案時，第二個 tabitem 上的資料網格未顯示過濾后的資料

如果我正確理解您的問題，那么您應該在屬性的設定器中設定Sourceof ：cvsAllSelectedCBItem

private string _selectedCBItem;
public string SelectedCBItem
{
    get { return _selectedCBItem; }
    set
    {
        _selectedCBItem = value;
        cvsAll.Source = m.GetBills_Pen(value); // <--
        OnPropertyChanged("SelectedCBItem");
    }
}

uj5u.com熱心網友回復：

使用@Firo 顯示的方法，我已經成功地在我的應用程式中實施（所以我將他的答案標記為已接受），這就是我最終得到的結果（以防它幫助任何可能有類似問題的人）

public class Model
{
    private List<Bills> _sBills;

    public List<Bills> SBills
    {
        get
        {
            if (_sBills == null) LoadAllBillsFromDatabase();
            
            return _sBills;
        }
    }

    

    public List<Bills> FilteredBills { get; private set; }

    public void LoadAllBillsFromDatabase()
    {
        SQLiteConnection m_dbConnection = new SQLiteConnection(@"Data Source=Bills.db;");
        SQLiteCommand sqlCom = new SQLiteCommand(@"Select * From billdata", m_dbConnection);
        SQLiteDataAdapter sda = new SQLiteDataAdapter(sqlCom);
        DataTable dt = new DataTable();
        sda.Fill(dt);
        _sBills = new List<Bills>();
        
        foreach (DataRow row in dt.Rows)
        {
            _sBills.Add(new Bills()
                        {
                            Id = Convert.ToInt32(row["Id"]),
                            Party = (string)row["Party"],
                            BillNo = (string)row["BillNo"],
                            BillDt = (string)(row["BillDt"]),
                            Amt = (string)row["Amt"],
                            DueDt = (string)(row["DueDt"]),
                            PaidOn = (string)(row["PaidOn"])
                        });
            
        }
        m_dbConnection.Close();
    }

}

public class BillsViewModel : ViewModelBase
{
    
    CollectionViewSource cvsAll = new CollectionViewSource();
    
    private List<Bills> _allBills;

    public BillsViewModel()
    {
        cvsAll.Source = m.FilteredBills;

        _allBills = m.SBills;
        AllBills = new ListCollectionView(_allBills)
        {
            Filter = o => ((Bills)o).PaidOn==""
        };
        ComboItems = _allBills.Select(b => b.Party).Distinct().OrderBy(b => b).ToList();
        FilteredBills = new ListCollectionView(_allBills)
        {
            Filter = o => ((Bills)o).Party == SelectedCBItem && ((Bills)o).PaidOn==""
        };
    }

    Model m = new Model();

    public ICollectionView AllBills { get; private set; }
    public ICollectionView FilteredBills { get; private set; }

    public List<string> ComboItems { get; private set; }

    private string _selectedCBItem;
    public string SelectedCBItem
    {
        get { return _selectedCBItem; }
        set
        {

            SetValue(ref _selectedCBItem, value);
            FilteredBills.Refresh();
            
        }
    }
}

第一個 tabitem 的 datagrid 中的AllBillsitemsource 是，第二個 tabitem 的 datagrid 中的 itemsource 是FilteredBills

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標籤：C＃ wpf 虚拟机数据网格

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