我正在使用sqlite数据库开发一个Windows Phone应用程序。我能够显示数据库并删除我要删除的特定行。但问题是在我选择行并单击删除后行不会消失那个时候。我必须租用那个页面才能看到它被删除了。 下面是我使用click_delete事件的类的代码
public partial class History : PhoneApplicationPage
{
ObservableCollection<historyTableSQlite> DB_HistoryList = new ObservableCollection<historyTableSQlite>();
DbHelper Db_helper = new DbHelper();
//public static int Selected_HistoryId;
//int Selected_HistoryId;
public static int Selected_HistoryId {get; set;}
// string dbPath = Path.Combine(Windows.Storage.ApplicationData.Current.LocalFolder.Path, "db.sqlite");
public History()
{
InitializeComponent();
}
protected override void OnNavigatedTo(NavigationEventArgs e)
{
Db_helper.AddInfo();
ReadHistoryList_Loaded();
// Selected_HistoryId = int.Parse(NavigationContext.QueryString["SelectedHistoryID"]);
}
public void ReadHistoryList_Loaded()
{
ReadAllContactsList dbhistory = new ReadAllContactsList();
DB_HistoryList = dbhistory.GetAllHistory();//Get all DB contacts
ListData.ItemsSource = DB_HistoryList.OrderByDescending(i => i.Id).ToList();
//Latest contact ID can Display first
}
public void ListData_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
if (ListData.SelectedIndex != -1)
{
historyTableSQlite listitem = ListData.SelectedItem as historyTableSQlite;
History.Selected_HistoryId = listitem.Id;
}
}
private void Delete_Click(object sender, EventArgs e)
{
Db_helper.DeleteContact(History.Selected_HistoryId);
NavigationService.Navigate(new Uri("/History.xaml", UriKind.Relative));
}
private void DeleteAll_Click(object sender, EventArgs e)
{
DbHelper Db_helper = new DbHelper();
Db_helper.DeleteAllContact();//delete all DB contacts
DB_HistoryList.Clear();//Clear collections
ListData.ItemsSource = DB_HistoryList;
}
}
}
是具有所有主要功能的类
public class DbHelper
{
SQLiteConnection dbConn;
public async Task<bool> onCreate(string DB_PATH)
{
try
{
if (!CheckFileExists(DB_PATH).Result)
{
using (dbConn = new SQLiteConnection(DB_PATH))
{
dbConn.CreateTable<historyTableSQlite>();
}
}
return true;
}
catch
{
return false;
}
}
private async Task<bool> CheckFileExists(string fileName)
{
try
{
var store = await Windows.Storage.ApplicationData.Current.LocalFolder.GetFileAsync(fileName);
return true;
}
catch
{
return false;
}
}
//retrieve all list from the database
public ObservableCollection<historyTableSQlite> ReadHistory()
{
using (var dbConn = new SQLiteConnection(App.DB_PATH))
{
List<historyTableSQlite> myCollection = dbConn.Table<historyTableSQlite>().ToList<historyTableSQlite>();
ObservableCollection<historyTableSQlite> HistoryList = new ObservableCollection<historyTableSQlite>(myCollection);
return HistoryList;
}
}
// Insert the new info in the histrorytablesqlite table.
public void Insert(historyTableSQlite newcontact)
{
using (var dbConn = new SQLiteConnection(App.DB_PATH))
{
dbConn.RunInTransaction(() =>
{
dbConn.Insert(newcontact);
});
}
}
public void AddInfo()
{
DbHelper Db_helper = new DbHelper();
Db_helper.Insert((new historyTableSQlite
{
Date = DateTime.Now.ToShortDateString(),
Time = DateTime.Now.ToShortTimeString(),
Zone = Checkin.Zone_st,
Floor = Checkin.Floor_st,
latitude = Checkin.Latitud_do,
longtitude = Checkin.Longtitude_do
}));
}
// Delete specific contact
public void DeleteContact(int Id)
{
using (var dbConn = new SQLiteConnection(App.DB_PATH))
{
var existingvalue = dbConn.Query<historyTableSQlite>("select * from historyTableSQlite where Id =" + Id).FirstOrDefault();
if (existingvalue != null)
{
dbConn.RunInTransaction(() =>
{
dbConn.Delete(existingvalue);
});
}
}
}
//Delete all contactlist or delete Contacts table
public void DeleteAllContact()
{
using (var dbConn = new SQLiteConnection(App.DB_PATH))
{
//dbConn.RunInTransaction(() =>
// {
dbConn.DropTable<historyTableSQlite>();
dbConn.CreateTable<historyTableSQlite>();
dbConn.Dispose();
dbConn.Close();
//});
}
}
是包含所有表的类
public class historyTableSQlite : INotifyPropertyChanged
{
[SQLite.PrimaryKey, SQLite.AutoIncrement]
public int Id
{
get;
set;
}
private int idValue;
private string dateValue = string.Empty;
public string Date
{
get { return this.dateValue; }
set
{
if (value != this.dateValue)
{
this.dateValue = value;
NotifyPropertyChanged("Date");
}
}
}
private string timeValue = string.Empty;
public string Time
{
get { return this.timeValue; }
set
{
if (value != this.timeValue)
{
this.timeValue = value;
NotifyPropertyChanged("Time");
}
}
}
private string floorValue = string.Empty;
public string Floor
{
get { return this.floorValue; }
set
{
if (value != this.floorValue)
{
this.floorValue = value;
NotifyPropertyChanged("Floor");
}
}
}
public string zoneValue;
public string Zone
{
get { return this.zoneValue; }
set
{
if (value != this.zoneValue)
{
this.zoneValue = value;
NotifyPropertyChanged("Zone");
}
}
}
private double latValue;
public double latitude
{
get { return latValue; }
set
{
if (value != this.latValue)
{
this.latValue = value;
NotifyPropertyChanged("Latitude");
}
}
}
private double lonValue;
public double longtitude
{
get { return this.lonValue; }
set
{
if (value != this.lonValue)
{
this.lonValue = value;
NotifyPropertyChanged("Longitude");
}
}
}
// public string isMarkPoint { get; set; }
public historyTableSQlite()
{
}
public historyTableSQlite(string date, string time, string floor, string zone, double lat, double lng)
{
Date = date;
Time = time;
Floor = floor;
Zone = zone;
latitude = lat;
longtitude = lng;
}
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged(String info)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(info));
}
}
}
答案 0 :(得分：0)
如果您从ObservableCollection删除该项目，它将通知ListBox更新其容器。
在您的代码中
// this is correct
ObservableCollection<historyTableSQlite> DB_HistoryList = new ObservableCollection<historyTableSQlite>();
但问题是您实际上并未将ListBox与相关联。
在您的代码中，您创建了一个副本（以及您尝试执行的最糟糕的副本），并将ListBox ItemsSource设置为它。见下文（你有这个）
ListData.ItemsSource = DB_HistoryList.OrderByDescending(i => i.Id).ToList();
基本上，你的ListBox不是ObservableCollection，而是List结构。
删除和插入列表不会更新ListBox的UI。
删除此列表，找到另一种方法对ObservableCollection进行排序。
然后你基本上可以这样做
ListData.ItemsSource = DB_HistoryList; // set the listbox to the actual obs collection
DB_HistoryList.RemoveAt(i); // remove the item at index i
DB_HistoryList.RemoveItem(object); // remove the object that matches