绑定的形式组合框到数据表的DataContext [英] Binding forms ComboBox to DataTable DataContext
问题描述
我通常能够解决我的问题，约五分钟搜索，但是这一次采取了几天没有结果，所以我会尽力提出这个问题。
我的DataContext设置为一个DataTable中的一个表（将preFER LINQ到SQL，但我坚持瓦特/的Sybase缺少现代的实体框架很好的支持。）我有一个组合框源来自其他DataTable中要更新表格上的数据表中的列，但我似乎无法获得绑定的SelectedValue正常工作。
我在输出窗口，我不能确定如何解决获得绑定错误，但它指出了问题的原因：
System.Windows.Data错误：40：BindingEx pression路径错误：'颜色'属性不是'对象'''数据表（散列code = 1796783）'中。 BindingEx pression：路径=颜色; DataItem的=数据表（散列code = 1796783）;目标元素是'组合框'（名称='cboColor'）;目标属性的SelectedValue（类型'对象'）
我创建了一个示例应用程序，再现问题，并提供在此背后的XAML和code
在此先感谢您的帮助
＆LT;窗口x：类=WPFTestBed.ComboTest
的xmlns =http://schemas.microsoft.com/winfx/2006/xaml/$p$psentation
的xmlns：X =http://schemas.microsoft.com/winfx/2006/xaml
标题=ComboTest高度=300宽度=300
加载=的OnLoad＆GT;
＆LT;电网＆GT;
＆LT; Grid.ColumnDefinitions＆GT;
＆LT; ColumnDefinition WIDTH =126 */＆GT;
＆LT; ColumnDefinition WIDTH =152 */＆GT;
＆LT; /Grid.ColumnDefinitions>
＆LT;数据网格的AutoGenerateColumns =FALSE高度=243保证金=8,6,0,0NAME =dgListVerticalAlignment =热门CanUserAddRows =假的ItemsSource ={结合}的SelectionChanged =dgList_SelectionChanged ＆GT;
＆LT; DataGrid.Columns＆GT;
＆LT; DataGridTextColumn标题=名称的IsReadOnly =真绑定={绑定路径=名}WIDTH =*/＆GT;
＆LT; DataGridTextColumn标题=颜色的IsReadOnly =真绑定={绑定路径=颜色}WIDTH =自动/＆GT;
＆LT; /DataGrid.Columns>
＆LT; /数据网格＆GT;
＆LT;电网Grid.Column =1高度=207的HorizontalAlignment =左保证金=6,6,0,0NAME =grdSelectionVerticalAlignment =热门WIDTH =140的DataContext ={结合}＆GT;
＆LT; TextBlock的高度=23的HorizontalAlignment =左保证金=6,6,0,0NAME =textBlock1文本={绑定路径=名}VerticalAlignment =热门/＆GT;
＆LT; TextBlock的高度=23的HorizontalAlignment =左保证金=6,27,0,0NAME =textBlock2文本={绑定路径=颜色}VerticalAlignment =热门/＆GT;
＆LT;组合框高度=23的HorizontalAlignment =左保证金=6,56,0,0NAME =cboColorVerticalAlignment =热门WIDTH =120
的ItemsSource ={结合}的DisplayMemberPath =colorNameSelectedValuePath =colorName的SelectedValue ={绑定路径=颜色}/＆GT;
＆LT; /网格＆GT;
＆LT;按钮内容=_保存Grid.Column =1高度=23的HorizontalAlignment =右保证金=0,0,6,12NAME =btnSaveVerticalAlignment =底部WIDTH =75 点击=btnSave_Click/＆GT;
＆LT; /网格＆GT;
$ C $后面ç
使用系统;
使用System.Collections.Generic;
使用System.Linq的;
使用System.Text;
使用System.Windows;
使用System.Windows.Controls的;
使用System.Windows.Data;
使用System.Windows.Documents;
使用System.Windows.Input;
使用System.Windows.Media;
使用System.Windows.Media.Imaging;
使用System.Windows.Shapes;
使用System.Data这;
命名空间WPFTestBed
{
///＆LT;总结＆gt;
///为ComboTest.xaml交互逻辑
///＆LT; /总结＆gt;
公共部分类ComboTest：窗口
{
公共ComboTest（）
{
的InitializeComponent（）;
}
私人数据表的GetList（）
{
数据表DT =新的DataTable（）;
DataRow的列;
dt.Columns.Add（新的DataColumn（名字））;
dt.Columns.Add（新的DataColumn（颜色））;
行= dt.NewRow（）;行[名称] =安倍;行[颜色] =红; dt.Rows.Add（行）;
行= dt.NewRow（）;行[名称] =鲍勃;行[颜色] =黄色; dt.Rows.Add（行）;
行= dt.NewRow（）;行[名称] =夹头;行[颜色] =蓝; dt.Rows.Add（行）;
行= dt.NewRow（）;行[名称] =道;行[颜色] =红; dt.Rows.Add（行）;
行= dt.NewRow（）;行[名称] =埃迪;行[颜色] =黄色; dt.Rows.Add（行）;
行= dt.NewRow（）;行[名称] =弗雷德;行[颜色] =蓝; dt.Rows.Add（行）;
返回DT;
}
私人数据表getColors（）
{
数据表DT =新的DataTable（）;
DataRow的列;
dt.Columns.Add（新的DataColumn（colorName））;
行= dt.NewRow（）;行[colorName] =红; dt.Rows.Add（行）;
行= dt.NewRow（）;行[colorName] =黄色; dt.Rows.Add（行）;
行= dt.NewRow（）;行[colorName] =蓝; dt.Rows.Add（行）;
返回DT;
}
私人无效的OnLoad（对象发件人，RoutedEventArgs E）
{
dgList.DataContext =的GetList（）;
cboColor.DataContext = getColors（）;
}
私人无效dgList_SelectionChanged（对象发件人，SelectionChangedEventArgs E）
{
//获取所选择的项目
DataRowView的selectedRow =（DataRowView的）dgList.SelectedCells [0] .Item;
//对于说明性的目的 - 在现实生活用于在DataContext的数据表将来自数据库
数据表DT =新的DataTable（）;
dt.Columns.Add（新的DataColumn（名字））;
dt.Columns.Add（新的DataColumn（颜色））;
DataRow的行= dt.NewRow（）; 。行[名称] = selectedRow [名称]的ToString（）;行[颜色] = selectedRow [颜色]; dt.Rows.Add（行）;
//设置数据上下文的形式
grdSelection.DataContext = DT;
}
私人无效btnSave_Click（对象发件人，RoutedEventArgs E）
{
数据表DT =（数据表）grdSelection.DataContext;
// DT没有被更新的组合框结合预期
}
}
}
现在的问题是，当你绑定列表中的颜色，数据上下文被搞砸了：
cboColor.DataContext = getColors（）;
需要保持绑定到数据表的组合框的数据上下文。在这个例子中的应用程序，你可以做直接设置项目源独自离开其数据方面：
cboColor.ItemsSource = getColors（）AsDataView（）;
I'm usually able to solve my problems with about five minutes of searching but this one has taken several days with no results, so I'll try posing the question.
I have a Form whose DataContext is set to a datatable (would prefer LINQ to SQL but I am stuck w/ Sybase which lacks good support for modern entity frameworks.) I have a combo box sourced by another datatable that should update a column on the forms data table but I can't seem to get the binding for SelectedValue to work correctly.
I get a binding error in my Output window which I am unsure how to resolve but it points to the cause of the problem:
System.Windows.Data Error: 40 : BindingExpression path error: 'color' property not found on 'object' ''DataTable' (HashCode=1796783)'. BindingExpression:Path=color; DataItem='DataTable' (HashCode=1796783); target element is 'ComboBox' (Name='cboColor'); target property is 'SelectedValue' (type 'Object')
I've created a sample app that recreates the problem and provide the Xaml and code behind here
Thanks in advance for your help
<Window x:Class="WPFTestBed.ComboTest"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="ComboTest" Height="300" Width="300"
Loaded="OnLoad">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="126*" />
<ColumnDefinition Width="152*" />
</Grid.ColumnDefinitions>
<DataGrid AutoGenerateColumns="False" Height="243" Margin="8,6,0,0" Name="dgList" VerticalAlignment="Top" CanUserAddRows="False" ItemsSource="{Binding}" SelectionChanged="dgList_SelectionChanged">
<DataGrid.Columns>
<DataGridTextColumn Header="Name" IsReadOnly="True" Binding="{Binding Path=name}" Width="*"/>
<DataGridTextColumn Header="Color" IsReadOnly="True" Binding="{Binding Path=color}" Width="Auto"/>
</DataGrid.Columns>
</DataGrid>
<Grid Grid.Column="1" Height="207" HorizontalAlignment="Left" Margin="6,6,0,0" Name="grdSelection" VerticalAlignment="Top" Width="140" DataContext="{Binding}">
<TextBlock Height="23" HorizontalAlignment="Left" Margin="6,6,0,0" Name="textBlock1" Text="{Binding Path=name}" VerticalAlignment="Top" />
<TextBlock Height="23" HorizontalAlignment="Left" Margin="6,27,0,0" Name="textBlock2" Text="{Binding Path=color}" VerticalAlignment="Top" />
<ComboBox Height="23" HorizontalAlignment="Left" Margin="6,56,0,0" Name="cboColor" VerticalAlignment="Top" Width="120"
ItemsSource="{Binding}" DisplayMemberPath="colorName" SelectedValuePath="colorName" SelectedValue="{Binding Path=color}" />
</Grid>
<Button Content="_Save" Grid.Column="1" Height="23" HorizontalAlignment="Right" Margin="0,0,6,12" Name="btnSave" VerticalAlignment="Bottom" Width="75" Click="btnSave_Click" />
</Grid>
Code behind
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;
using System.Data;
namespace WPFTestBed
{
/// <summary>
/// Interaction logic for ComboTest.xaml
/// </summary>
public partial class ComboTest : Window
{
public ComboTest()
{
InitializeComponent();
}
private DataTable getList()
{
DataTable dt = new DataTable();
DataRow row;
dt.Columns.Add(new DataColumn("name"));
dt.Columns.Add(new DataColumn("color"));
row = dt.NewRow(); row["name"] = "abe"; row["color"] = "Red"; dt.Rows.Add(row);
row = dt.NewRow(); row["name"] = "bob"; row["color"] = "Yellow"; dt.Rows.Add(row);
row = dt.NewRow(); row["name"] = "chuck"; row["color"] = "Blue"; dt.Rows.Add(row);
row = dt.NewRow(); row["name"] = "doug"; row["color"] = "Red"; dt.Rows.Add(row);
row = dt.NewRow(); row["name"] = "eddie"; row["color"] = "Yellow"; dt.Rows.Add(row);
row = dt.NewRow(); row["name"] = "fred"; row["color"] = "Blue"; dt.Rows.Add(row);
return dt;
}
private DataTable getColors()
{
DataTable dt = new DataTable();
DataRow row;
dt.Columns.Add(new DataColumn("colorName"));
row = dt.NewRow(); row["colorName"] = "Red"; dt.Rows.Add(row);
row = dt.NewRow(); row["colorName"] = "Yellow"; dt.Rows.Add(row);
row = dt.NewRow(); row["colorName"] = "Blue"; dt.Rows.Add(row);
return dt;
}
private void OnLoad(object sender, RoutedEventArgs e)
{
dgList.DataContext = getList();
cboColor.DataContext = getColors();
}
private void dgList_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
// Get the selected Item
DataRowView selectedRow = (DataRowView)dgList.SelectedCells[0].Item;
//For Illustrative purposes - in "real life" the data table used for the DataContext would come from the database
DataTable dt = new DataTable();
dt.Columns.Add(new DataColumn("name"));
dt.Columns.Add(new DataColumn("color"));
DataRow row = dt.NewRow(); row["name"] = selectedRow["name"].ToString(); row["color"] = selectedRow["color"]; dt.Rows.Add(row);
// Set the data context for the form
grdSelection.DataContext = dt;
}
private void btnSave_Click(object sender, RoutedEventArgs e)
{
DataTable dt = (DataTable)grdSelection.DataContext;
// dt is not updated by combobox binding as expected
}
}
}
The problem is that when you bind the list to the colors, the data context gets screwed up:
cboColor.DataContext = getColors();
Need to keep the ComboBox's data context bound to the DataTable. In the example app, you could do by setting the items source directly and leaving its data context alone:
cboColor.ItemsSource = getColors().AsDataView();
这篇关于绑定的形式组合框到数据表的DataContext的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
