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如何在Xamarin.Forms的列表視圖中檢索自定義單元格的輸入單元格的文本

[英]How to retrieve text of entry cell of custom cell in a list view in Xamarin.Forms

 原文  2016-03-25 12:36:30  3   1    listview/ xamarin/ xamarin.forms

問題描述

我是Xamarin.Forms的新手，我創建了一個包含4個標簽和1個條目的“自定義”單元格的列表。 我設法顯示標簽和條目。 但是我想使用Entry單元格中的文本。 怎么做？ 我的UI是像這樣

下面是代碼模型 

public class DSO_beat_Retailer_mapping
{
    [PrimaryKey, AutoIncrement]
    public int _id{ get; set;}
    public string DSO_CD{ get; set;}
    public string Beat_id{ get; set;}
    public string Retailer_cd{ get; set;}
    public string Retailer_nm{ get; set;}
    public string email{ get; set;}
    public string mobile{ get; set;}
    public DateTime birth_dt{ get; set;}
    public DateTime Anniversary_dt{ get; set;}
    public DateTime Lst_sync_dt{ get; set;}

}

以下是頁面 

public class RetailerListPage : ContentPage
{
    public RetailerListPage()
    {
        BackgroundColor = Color.White;
        Title = "Retailer List";

        CreateNewDB database = new CreateNewDB();
        database.saveDSOReatilMap(retailerlst);

        // Fetch data from LOCAL TABLE DSO_beat_Retailer_mapping
        List<DSO_beat_Retailer_mapping> RetailerList = database.GetDSOReatilMap("Select * from DSO_beat_Retailer_mapping ").ToList();

        ListView listview = new ListView();
        listview.RowHeight = 100;
        listview.ItemsSource = RetailerList;
        listview.ItemTemplate = new DataTemplate(typeof(CustomCell));  

        this.Content = listview;
    }

public class CustomCell : ViewCell
    {
        public CustomCell()
        {
    //Please Condider 4 labes & 1 Entry cell is created though below code have 1 label & 1 entry

            AbsoluteLayout cellView = new AbsoluteLayout();
            var retailernameLabel = new Label();
            AbsoluteLayout.SetLayoutBounds(retailernameLabel, new Rectangle(5, 12 , AbsoluteLayout.AutoSize,AbsoluteLayout.AutoSize));
            retailernameLabel.SetBinding(Label.TextProperty, new Binding("Retailer_nm"));
            retailernameLabel.FontSize = 18;
            retailernameLabel.TextColor = Color.FromHex("#434343");
            cellView.Children.Add(retailernameLabel);

    //Remaining 3 labels goes here

            var txtAmt = new Entry();
            AbsoluteLayout.SetLayoutBounds(txtAmt, new Rectangle(5, 32, 500, 60));
            txtAmt.SetBinding(Entry.TextProperty, new Binding("inputAmt"));
            txtAmt.Keyboard = Keyboard.Numeric;
            txtAmt.TextColor = Color.Black;
            cellView.Children.Add(txtAmt);

            this.View = cellView;

            View = new StackLayout()
            {
                BackgroundColor = rowcolor,
                Children = { cellView }
            };

        }
    }

}

另外，請指定上述代碼中的錯誤以及綁定數據的正確方法是什么。

代碼更改如下 

public class RetailerListPage : ContentPage
{
    public RetailerListPage()
    {
        BackgroundColor = Color.White;
        Title = "Retailer List";

        BindingContext = new RetailerListPageViewModel();

        ListView listview = new ListView();
        listview.RowHeight = 100;

        listview.ItemTemplate = new DataTemplate(typeof(CustomCell));

        listview.SetBinding(ListView.ItemsSourceProperty, "RetailerList");

        Content = listview;
    }

    public class CustomCell : ViewCell
    {
        public CustomCell()
        {
           #region Code that Customizes Cell

            AbsoluteLayout cellView = new AbsoluteLayout();
            var retailernameLabel = new Label();
            AbsoluteLayout.SetLayoutBounds(retailernameLabel, new Rectangle(5, 12, AbsoluteLayout.AutoSize, AbsoluteLayout.AutoSize));
            retailernameLabel.SetBinding(Label.TextProperty, new Binding("Retailer_nm"));
            retailernameLabel.FontSize = 18;
            retailernameLabel.TextColor = Color.FromHex("#434343");
            cellView.Children.Add(retailernameLabel);

            var txtAmt = new Entry();
            AbsoluteLayout.SetLayoutBounds(txtAmt, new Rectangle(5, 32, 500, 60));
            txtAmt.SetBinding(Entry.TextProperty, new Binding("InputAmt"));
            txtAmt.Keyboard = Keyboard.Numeric;
            txtAmt.TextColor = Color.Black;
            cellView.Children.Add(txtAmt);

            this.View = cellView;

            View = new StackLayout()
            {
              Children = { cellView }
            };
            #endregion
        }
    }

}

為模型中的inputAmt添加了一個新屬性，如下所示 

public class DSO_beat_Retailer_mapping: INotifyPropertyChanged
{
    public string _inputAmt;  //NEWLY ADDED
    public int _id;
    public string _DSO_CD;
    public string _Beat_id;
    public string _Retailer_cd;
    public string _Retailer_nm;
    public string _email;
    public string _mobile;
    public DateTime _birth_dt;
    public DateTime _Anniversary_dt;
    public DateTime _Lst_sync_dt;
    public string InputAmt
    {
        get
        {
            return _inputAmt;
        }

        set
        {
            _inputAmt = value;
            OnPropertyChanged("inputAmt");
        }
    }

    public int Id
    {
        get
        {
            return _id;
        }

        set
        {
            _id = value;
            OnPropertyChanged("ID");
        }
    }

    public string DSO_CD
    {
        get
        {
            return _DSO_CD;
        }

        set
        {
            _DSO_CD = value;
            OnPropertyChanged("DSO_CD");
        }
    }

    public string Beat_id
    {
        get
        {
            return _Beat_id;
        }

        set
        {
            _Beat_id = value;
            OnPropertyChanged("Beat_id");
        }
    }

    public string Retailer_cd
    {
        get
        {
            return _Retailer_cd;
        }

        set
        {
            _Retailer_cd = value;
            OnPropertyChanged("Retailer_cd");
        }
    }

    public string Retailer_nm
    {
        get
        {
            return _Retailer_nm;
        }

        set
        {
            _Retailer_nm = value;
            OnPropertyChanged("Retailer_nm");
        }
    }

    public string email
    {
        get
        {
            return _email;
        }

        set
        {
            _email = value;
            OnPropertyChanged("email");
        }
    }

    public string mobile
    {
        get
        {
            return _mobile;
        }

        set
        {
            _mobile = value;
            OnPropertyChanged("mobile");
        }
    }

    public DateTime birth_dt
    {
        get
        {
            return _birth_dt;
        }

        set
        {
            _birth_dt = value;
            OnPropertyChanged("birth_dt");
        }
    }

    public DateTime Anniversary_dt
    {
        get
        {
            return _Anniversary_dt;
        }

        set
        {
            _Anniversary_dt = value;
            OnPropertyChanged("Anniversary_dt");
        }
    }

    public DateTime Lst_sync_dt
    {
        get
        {
            return _Lst_sync_dt;
        }

        set
        {
            _Lst_sync_dt = value;
            OnPropertyChanged("Lst_sync_dt");
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
    public void OnPropertyChanged(string propertyName)
    {
        if (this.PropertyChanged != null)
        {
            PropertyChangedEventArgs e = new PropertyChangedEventArgs(propertyName);
            this.PropertyChanged(this, e);
        }
    }
}

而且ViewModel如下 

 public class RetailerListPageViewModel : INotifyPropertyChanged
{
    private List<DSO_beat_Retailer_mapping> retailerList;

    public RetailerListPageViewModel()
    {
        #region Here data inserted for test purpose 
        //DSO_beat_Retailer_mapping retailerlst = new DSO_beat_Retailer_mapping
        //{
        //    InputAmt = "200",
        //    _id = 1,
        //    DSO_CD = "123",
        //    Beat_id = "111",
        //    Retailer_nm = "XYZ RETAILER",
        //    email = "ZYZ@ABCD.com",
        //    mobile = "1234567890",
        //    birth_dt = DateTime.Now,
        //    Anniversary_dt = DateTime.Now,
        //    Lst_sync_dt = DateTime.Now
        //};

        //DSO_beat_Retailer_mapping retailerlst1 = new DSO_beat_Retailer_mapping
        //{
        //    InputAmt = "200",
        //    _id = 1,
        //    DSO_CD = "123",
        //    Beat_id = "111",
        //    Retailer_cd = "R123",
        //    Retailer_nm = "XYZ RETAILER",
        //    email = "ZYZ@ABCD.com",
        //    mobile = "1234567890",
        //    birth_dt = DateTime.Now,
        //    Anniversary_dt = DateTime.Now,
        //    Lst_sync_dt = DateTime.Now
        //};
        #endregion

        CreateNewDB database = new CreateNewDB();
        //database.saveDSOReatilMap(retailerList);  
        //database.saveDSOReatilMap(retailerlst1);

       RetailerList = database.GetDSOReatilMap("Select * from DSO_beat_Retailer_mapping ").ToList();
    }

        public List<DSO_beat_Retailer_mapping> RetailerList
    {
        get { return retailerList; }

        set
        {
            retailerList = value;
            OnPropertyChanged("RetailerList");
        }
    }

    public Command btnSave
    {
        get
        {
            return new Command(() => {
                // Code to save List 

            });
        }
    }


    public event PropertyChangedEventHandler PropertyChanged;

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

以下CreateNewDB是訪問數據庫的類 

public class CreateNewDB
{
    static object locker = new object ();
    SQLiteConnection database;

    public CreateNewDB ()
    {

        database = DependencyService.Get<ISQLite> ().GetConnection ();

        database.DropTable<DSO_beat_Retailer_mapping> ();
        database.CreateTable<DSO_beat_Retailer_mapping> ();
    }


    //DSO_beat_Retailer_mapping
    public IEnumerable<DSO_beat_Retailer_mapping> GetDSOReatilMap(string query)
    {
        lock (locker) {
            return database.Query<DSO_beat_Retailer_mapping> (query);
        }
    }

    public string saveDSOReatilMap(DSO_beat_Retailer_mapping item)
    {
        lock (locker) {
            database.Insert(item);
            return item.Retailer_cd;
        }
    }
//UPDATE DB  
public string UpdateDSOReatilMap(DSO_beat_Retailer_mapping item)
    {
        lock (locker)
        {
            database.Update(item);
            return item.Retailer_cd;
        }
    }
    public int DeleteDSOReatilMap(string empcd)
    {
        lock (locker) {
            return database.Delete<DSO_beat_Retailer_mapping> (empcd);
        }
    }


}

我的問題是：

  1. 仍然無法填充列表
  2. 我需要在RetailerListPage上添加NEXT BUTTON（如附件圖像所示），以便可以在下一頁上使用詳細信息。
  3. 無法獲取數據庫中的UPDATED詳細信息，即（金額）

請指導。

1 個解決方案

解決方案1
 2  2016-03-25 14:02:03

Xamarin.Forms廣泛使用的模式是MVVM模式（代表Model View ViewModel）。 它用於將特定的UI代碼與業務邏輯代碼分開。 按照該模式，您可以創建ViewModel類，該類為View准備數據並允許將View與Model連接（因此得名）。 重要的部分是INotifyPropertyChanged接口，它允許將ViewModel實際綁定到View。 ViewModel應該實現此接口，以通知視圖有關ViewModel中發生的更改。 然后，當ViewModel中發生某些事情時，它應該引發OnPropertyChanged方法，該方法實際上將通知發送給視圖。 其他重要的部分是視圖必須知道向哪個ViewModel訂閱通知。 為此，我們使用BindingContext屬性。 請參考以下代碼，我認為應該清楚。

在你的情況，我們可以創建RetailerListPageViewModel為RetailerListPage ： 

public class RetailerListPageViewModel : INotifyPropertyChanged
{
    private List<DSO_beat_Retailer_mapping> retailerList;

    public RetailerListPageViewModel()
    {
        CreateNewDB database = new CreateNewDB();
        database.saveDSOReatilMap(retailerlst);

        // Fetch data from LOCAL TABLE DSO_beat_Retailer_mapping
        RetailerList = database
                               .GetDSOReatilMap("Select * from DSO_beat_Retailer_mapping ")
                               .ToList();
    }


    public List<DSO_beat_Retailer_mapping> RetailerList
    {
        get { return retailerList; }
        set 
        { 
            retailerList = value; 
            OnPropertyChanged("RetailerList");
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
    public void OnPropertyChanged(string propertyName)
    {
        if (this.PropertyChanged != null)
        {
            PropertyChangedEventArgs e = new PropertyChangedEventArgs(propertyName);
            this.PropertyChanged(this, e);
        }
    }
}

現在，我們可以修改RetailerListPage以使用我們創建的ViewModel（通過使用BindingContext屬性）： 

public class RetailerListPage : ContentPage
{
    public RetailerListPage()
    {
       BackgroundColor = Color.White;
       Title = "Retailer List";

       BindingContext = new RetailerListPageViewModel();

       ListView listview = new ListView();
       listview.RowHeight = 100;
       listview.ItemTemplate = new DataTemplate(typeof(CustomCell));

       listview.SetBinding(ListView.ItemsSourceProperty, "RetailerList");  

       this.Content = listview;
    }
}

當您將ListView綁定到某些數據集合時，每個CustomCell都會作為BindingContext獲得，並從該集合中分配一個項目。 您可以認為它現在成為CustomCell的ViewModel。 這實際上是解釋為什么顯示標簽的代碼起作用的原因。 因此，您嘗試將Entry.Text綁定到inputAmt屬性，但是DSO_beat_Retailer_mapping類中不存在名為inputAmt屬性。 因此，您需要使用該屬性和要顯示的其他屬性來創建ViewModel： 

public class BeatRetailerItemViewModel : INotifyPropertyChanged
{
    private string _inputAmt;  
    private string retailerNm;

    public string inputAmt
    {
        get { return _inputAmt; }
        set 
        { 
            _inputAmt= value; 
            OnPropertyChanged("inputAmt");
        }
    }

    public string Retailer_nm 
    { 
        get { return retailerNm; }
        set 
        { 
            retailerNm = value; 
            OnPropertyChanged("Retailer_nm");
        }
    }

    //and other properties that you need to display
    //and INotifyPropertyChanged implementation
}

好的，但是我們還沒有走出困境。 現在我們必須適當地修改RetailerListPageViewModel以使用新的ViewModel（我省略了INotifyPropertyChanged代碼，因為您可以在上面的示例中看到它）： 

public class RetailerListPageViewModel : INotifyPropertyChanged
{
    private List<BeatRetailerItemViewModel> retailerList;

    public RetailerListPageViewModel()
    {
        CreateNewDB database = new CreateNewDB();
        database.saveDSOReatilMap(retailerlst);

        // Fetch data from LOCAL TABLE DSO_beat_Retailer_mapping
        RetailerList = database
                               .GetDSOReatilMap("Select * from DSO_beat_Retailer_mapping ")
                               .Select(x => new BeatRetailerItemViewModel { Retailer_nm = x.Retailer_nm })
                               .ToList();
    }

    public List<BeatRetailerItemViewModel> RetailerList
    {
        get { return retailerList; }
        set 
        { 
            retailerList = value; 
            OnPropertyChanged("RetailerList");
        }
    }

    //INotifyPropertyChanged implementation
}

我希望你在那里看到模式:)

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