我正在使用基於小型SQLLite的數據庫構建應用程序。這在Windows Phone上運行良好。現在我試圖讓它與Xamarin Forms(Portable)一起工作。數據庫的建立和填充工作正在進行。現在我試圖在ListView中顯示錶格的元素,但是我在ListView中獲取我的Table Notes的項目時遇到問題。 我的表格註釋設置並充滿了兩個項目:Xamarin中的ListView表單綁定到數據庫錯誤
public class Notes
{
//The Id property is marked as the Primary Key
[SQLite.PrimaryKey, SQLite.AutoIncrement]
public int Id { get; set; }
public string Note { get; set; }
public DateTimeOffset NoteDate { get; set; }
public TimeSpan NoteStart { get; set; }
public Notes()
{
}
public Notes(string remark, DateTimeOffset notedate, TimeSpan noteStart)
{
Note = remark;
NoteDate = notedate;
NoteStart = noteStart;
}
}
db.Insert(new Notes("Test", DateTimeOffset.Now.AddDays(0), TimeSpan.Parse("7:45")));
db.Insert(new Notes("Test", DateTimeOffset.Now.AddDays(1), TimeSpan.Parse("7:45")));
我打電話的項目有:
public IEnumerable<Notes> GetItems()
{
{
return (from i in db.Table<Notes>() select i).ToList();
}
}
我有一個基於Contentpage一個XAML:
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="Todo.Views.DatePage">
<ListView x:Name="Listnotes">
<ListView.ItemTemplate>
<DataTemplate>
<Label Text="{Binding Note}" />
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</ContentPage>
的ListView的綁定在C#中執行:
NoteHelper nh = new NoteHelper();
private IEnumerable<Notes> notelist = new List<Notes>();
notelist = nh.GetItems((DateTimeOffset.Now));
Listnotes.ItemsSource = notelist;
當我在Windows Phone上構建解決方案時,我收到以下錯誤消息。我究竟做錯了什麼?
System.NullReferenceException:未將對象引用設置爲對象的實例。
at Xamarin.Forms.Platform.WinRT.CellControl.SetCell(Object newContext)
at Xamarin.Forms.Platform.WinRT.CellControl.MeasureOverride(Size availableSize)
at Windows.UI.Xaml.UIElement.Measure(Size availableSize)
at Xamarin.Forms.Platform.WinRT.VisualElementRenderer`2.MeasureOverride(Size availableSize)
at Windows.UI.Xaml.UIElement.Measure(Size availableSize)
at Xamarin.Forms.Platform.WinRT.VisualElementR
或者,如果你需要的是一個標籤,嘗試做了更好的性能如下: ' DataTemplate>' –
hvaughan3
感謝您的貢獻ViewCell的工作非常完美 –
@KeesDapperens沒問題,快樂的編碼 – SushiHangover