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[英]Calculated column in a dataGrid bound with a ObservableCollection
[英]DataGrid is not bound to the ObservableCollection
我的视图中有一个按钮,可以在ViewModel中执行此方法:
public void GetAudits(Guid? userId, DateTime? from, DateTime? to, string form)
{
StringBuilder sCondition = new StringBuilder("WHERE 0=0");
if (userId != null && userId != Guid.Empty)
sCondition.Append(string.Format(" AND UserId = '{0}' ", userId));
if (!string.IsNullOrEmpty(form))
sCondition.Append(string.Format(" AND FormName = '{0}' ", form));
string query = string.Format("SELECT * FROM Common.TbHistoryLog {0}", sCondition);
Audits = new ObservableCollection<HistoryLog>(oContext.Database.SqlQuery<HistoryLog>(query).ToList());
}
Audits
属性:
public ObservableCollection<HistoryLog> Audits
{
get
{
return audits;
}
set
{
audits = value;
}
}
ObservableCollection<HistoryLog> audits;
这是按钮的处理程序:
private void BtnSearch(object sender, RoutedEventArgs e)
{
var userId = ((TbUsers)cmbUsers.SelectedItem)?.UserId;
var from = dtFromDate.Value;
var to = dtToDate.Value;
var form = ((BlCommon.TbObjects)cmbForms.SelectedItem)?.ObjectRealName;
using (ClsUserTransactions oUserTrans = new ClsUserTransactions())
{
oUserTrans.GetAudits(userId, from, to, form);
}
}
但是当我单击按钮时,dataGrid不会使用Audits集合进行更新:
<DataGrid Name="gvHistory" Grid.Column="0" Grid.Row="9" Margin="2" Visibility="Visible" ItemsSource="{Binding Audits}" Grid.ColumnSpan="8" IsReadOnly="True" Grid.RowSpan="2" AutoGenerateColumns="True" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" CanUserAddRows="False"/>
当我调试时,我注意到没有碰到吸气块
您为什么不简单地清除并重新填充相同的ObservableCollection
public void GetAudits(Guid? userId, DateTime? from, DateTime? to, string form)
{
StringBuilder sCondition = new StringBuilder("WHERE 0=0");
if (userId != null && userId != Guid.Empty)
sCondition.Append(string.Format(" AND UserId = '{0}' ", userId));
if (!string.IsNullOrEmpty(form))
sCondition.Append(string.Format(" AND FormName = '{0}' ", form));
string query = string.Format("SELECT * FROM Common.TbHistoryLog {0}", sCondition);
if (Audits != null)
{
Audits.Clear();
var newItems = oContext.Database.SqlQuery<HistoryLog>(query).ToList();
if (newItems != null)
foreach (var newItem in newItems)
Audits.Add(newItem);
}
}
其次,这将创建一个新的ClsUserTransactions
实例 :
ClsUserTransactions oUserTrans = new ClsUserTransactions())
您需要向DataGrid
绑定的对象添加项目,并且在填充其Audits集合之后,您当然不应该立即处置该实例...:
private void BtnSearch(object sender, RoutedEventArgs e)
{
var userId = ((TbUsers)cmbUsers.SelectedItem)?.UserId;
var from = dtFromDate.Value;
var to = dtToDate.Value;
var form = ((BlCommon.TbObjects)cmbForms.SelectedItem)?.ObjectRealName;
ClsUserTransactions oUserTrans = gvHistory.DataContext as ClsUserTransactions;
oUserTrans.GetAudits(userId, from, to, form);
}
您的ViewModel应该实现INotifyPropertyChanged接口,然后在Audits setter上通知属性更改:
public class ViewModel : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged(string name)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(name));
}
}
...
-
public ObservableCollection<HistoryLog> Audits
{
get
{
return audits;
}
set
{
audits = value;
OnPropertyChanged("Audits");
}
}
ObservableCollection<HistoryLog> audits;
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