我在数据库表中添加了一个新列。当我添加这个新列时，第一次机会异常开始出现。当我调试它时，它说明了代码行
MLongListSelector.ItemsSource = c.ToDoList.ToList（）;
是导致问题的下一个执行语句。那我做错了什么？
using (DatabaseContext c = new DatabaseContext(DatabaseContext.ConnectionString))
{
c.CreateIfNotExists();
c.LogDebug = true;
//output todolist data from database
MLongListSelector.ItemsSource = c.ToDoList.ToList();
}
该行的堆栈跟踪：
ex.StackTrace " at System.Data.SqlServerCe.SqlCeCommand.ProcessResults(Int32 hr)\r\n at System.Data.SqlServerCe.SqlCeCommand.CompileQueryPlan()\r\n at System.Data.SqlServerCe.SqlCeCommand.ExecuteCommand(CommandBehavior behavior, String method, ResultSetOptions options)\r\n at System.Data.SqlServerCe.SqlCeCommand.ExecuteDbDataReader(CommandBehavior behavior)\r\n at System.Data.Linq.SqlClient.SqlProvider.Execute(Expression query, QueryInfo queryInfo, IObjectReaderFactory factory, Object[] parentArgs, Object[] userArgs, ICompiledSubQuery[] subQueries, Object lastResult, Boolean isCompiledQuery)\r\n at System.Data.Linq.SqlClient.SqlProvider.ExecuteAll(Expression query, QueryInfo[] queryInfos, IObjectReaderFactory factory, Object[] userArguments, ICompiledSubQuery[] subQueries, Boolean isCompiledQuery)\r\n at System.Data.Linq.SqlClient.SqlProvider.System.Data.Linq.Provider.IProvider.Execute(Expression query)\r\n at System.Data.Linq.Table`1.GetEnumerator()\r\n at System.Data.Linq.Table`1.System.Collections.Generic.IEnumerable<TEntity>.GetEnumerator()\r\n at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)\r\n at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)\r\n at PhoneApp.MainPage.OnNavigatedTo(NavigationEventArgs e)"
e.message：
ex.Message "The column name is not valid. [ Node name (if any) = t0,Column name = Col ]" string
获取并设置：
public partial class ToDoList : INotifyPropertyChanging, INotifyPropertyChanged
{
private static PropertyChangingEventArgs emptyChangingEventArgs = new PropertyChangingEventArgs(String.Empty);
private int _Id;
private string _Title;
private string _Description;
private string _Col;
#region Extensibility Method Definitions
partial void OnLoaded();
partial void OnValidate(System.Data.Linq.ChangeAction action);
partial void OnCreated();
partial void OnIdChanging(int value);
partial void OnIdChanged();
partial void OnTitleChanging(string value);
partial void OnTitleChanged();
partial void OnDescriptionChanging(string value);
partial void OnDescriptionChanged();
partial void OnColChanging(string value);
partial void OnColChanged();
#endregion
public ToDoList()
{
OnCreated();
}
[global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_Id", AutoSync=AutoSync.OnInsert, DbType="Int NOT NULL IDENTITY", IsPrimaryKey=true, IsDbGenerated=true)]
public int Id
{
get
{
return this._Id;
}
set
{
if ((this._Id != value))
{
this.OnIdChanging(value);
this.SendPropertyChanging();
this._Id = value;
this.SendPropertyChanged("Id");
this.OnIdChanged();
}
}
}
[global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_Title", DbType="NVarChar(100) NOT NULL", CanBeNull=false)]
public string Title
{
get
{
return this._Title;
}
set
{
if ((this._Title != value))
{
this.OnTitleChanging(value);
this.SendPropertyChanging();
this._Title = value;
this.SendPropertyChanged("Title");
this.OnTitleChanged();
}
}
}
[global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_Description", DbType="NVarChar(100)")]
public string Description
{
get
{
return this._Description;
}
set
{
if ((this._Description != value))
{
this.OnDescriptionChanging(value);
this.SendPropertyChanging();
this._Description = value;
this.SendPropertyChanged("Description");
this.OnDescriptionChanged();
}
}
}
[global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_Col", DbType="NVarChar(25)")]
public string Col
{
get
{
return this._Col;
}
set
{
if ((this._Col != value))
{
this.OnColChanging(value);
this.SendPropertyChanging();
this._Col = value;
this.SendPropertyChanged("Col");
this.OnColChanged();
}
}
}
public event PropertyChangingEventHandler PropertyChanging;
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void SendPropertyChanging()
{
if ((this.PropertyChanging != null))
{
this.PropertyChanging(this, emptyChangingEventArgs);
}
}
protected virtual void SendPropertyChanged(String propertyName)
{
if ((this.PropertyChanged != null))
{
this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}
答案 0 :(得分：1)
我刚试过你的解决方案而且我不明白它为什么不起作用。你有ToDoList标有“表属性”吗？即
[Table]
public partial class ToDoList : INotifyPropertyChanging, INotifyPropertyChanged
此外，您可能值得删除数据库并重新创建它。按照下面的代码示例尝试从那里开始。如果这不起作用，那么随意附上一个复制问题的简单项目。
<强>的Xaml
<Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
<ListBox x:Name="lstToDos">
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Title}"></TextBlock>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Grid>
代码
public partial class MainPage : PhoneApplicationPage
{
// Constructor
public MainPage()
{
InitializeComponent();
}
protected override void OnNavigatedTo(NavigationEventArgs e)
{
using (DatabaseContext c = new DatabaseContext(DatabaseContext.ConnectionString))
{
c.CreateIfNotExists();
//Add new records for debug sake:
var dateNow = DateTime.UtcNow.TimeOfDay.ToString();
var newToDo = new ToDoList { Col = "Col" + dateNow, Description = "Some description" + dateNow, Title = "Some title" + dateNow };
c.ToDoLists.InsertOnSubmit(newToDo);
c.SubmitChanges();
lstToDos.ItemsSource = c.ToDoLists.ToList();
}
}
}
数据上下文文件
public class DatabaseContext : DataContext
{
public DatabaseContext(string connectionString)
: base(connectionString)
{
}
public Table<ToDoList> ToDoLists
{
get
{
return this.GetTable<ToDoList>();
}
}
public void CreateIfNotExists()
{
if (!this.DatabaseExists())
{
this.CreateDatabase();
}
}
public const string ConnectionString = @"isostore:/MyDatabases.sdf";
}
ToDO实体
[Table]
public partial class ToDoList : INotifyPropertyChanging, INotifyPropertyChanged
{
private static PropertyChangingEventArgs emptyChangingEventArgs = new PropertyChangingEventArgs(String.Empty);
private int _Id;
private string _Title;
private string _Description;
private string _Col;
#region Extensibility Method Definitions
partial void OnLoaded();
partial void OnValidate(System.Data.Linq.ChangeAction action);
partial void OnCreated();
partial void OnIdChanging(int value);
partial void OnIdChanged();
partial void OnTitleChanging(string value);
partial void OnTitleChanged();
partial void OnDescriptionChanging(string value);
partial void OnDescriptionChanged();
partial void OnColChanging(string value);
partial void OnColChanged();
#endregion
public ToDoList()
{
OnCreated();
}
[global::System.Data.Linq.Mapping.ColumnAttribute(Storage = "_Id", AutoSync = AutoSync.OnInsert, DbType = "Int NOT NULL IDENTITY", IsPrimaryKey = true, IsDbGenerated = true)]
public int Id
{
get
{
return this._Id;
}
set
{
if ((this._Id != value))
{
this.OnIdChanging(value);
this.SendPropertyChanging();
this._Id = value;
this.SendPropertyChanged("Id");
this.OnIdChanged();
}
}
}
[global::System.Data.Linq.Mapping.ColumnAttribute(Storage = "_Title", DbType = "NVarChar(100) NOT NULL", CanBeNull = false)]
public string Title
{
get
{
return this._Title;
}
set
{
if ((this._Title != value))
{
this.OnTitleChanging(value);
this.SendPropertyChanging();
this._Title = value;
this.SendPropertyChanged("Title");
this.OnTitleChanged();
}
}
}
[global::System.Data.Linq.Mapping.ColumnAttribute(Storage = "_Description", DbType = "NVarChar(100)")]
public string Description
{
get
{
return this._Description;
}
set
{
if ((this._Description != value))
{
this.OnDescriptionChanging(value);
this.SendPropertyChanging();
this._Description = value;
this.SendPropertyChanged("Description");
this.OnDescriptionChanged();
}
}
}
[global::System.Data.Linq.Mapping.ColumnAttribute(Storage = "_Col", DbType = "NVarChar(25)")]
public string Col
{
get
{
return this._Col;
}
set
{
if ((this._Col != value))
{
this.OnColChanging(value);
this.SendPropertyChanging();
this._Col = value;
this.SendPropertyChanged("Col");
this.OnColChanged();
}
}
}
public event PropertyChangingEventHandler PropertyChanging;
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void SendPropertyChanging()
{
if ((this.PropertyChanging != null))
{
this.PropertyChanging(this, emptyChangingEventArgs);
}
}
protected virtual void SendPropertyChanged(String propertyName)
{
if ((this.PropertyChanged != null))
{
this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}