无法通过命令将值从视图传递到viewmodel
Posted
tags:
篇首语：本文由小常识网(cha138.com)小编为大家整理，主要介绍了无法通过命令将值从视图传递到viewmodel相关的知识，希望对你有一定的参考价值。
我正在为我的应用程序实现MVVM模式。我正在实现我的Views，ViewModel，Model和Commands and Converters。现在，我无法通过命令绑定将我的textboxes值从我的datatemplate传递给我的ViewModel。我可以单击按钮来尝试更新过程，但它无法传递文本框值。我的命令类有什么需要改变的吗？
这是我的XAML：
<DataGrid AutoGenerateColumns="False" Grid.Row="2" Grid.ColumnSpan="4" Grid.RowSpan="3" x:Name="productionLineConfigDataGrid" Margin="70,0.2,70,0" ItemsSource="{Binding listAllProductionLineConfigs}">
<DataTemplate>
<StackPanel>
<StackPanel Orientation="Horizontal">
<TextBlock FontSize="12" Text="ID: " VerticalAlignment="Center" />
<TextBlock x:Name="txtBlockLineId" FontSize="16" Foreground="MidnightBlue" Text="{Binding ProductionLineId, Mode=TwoWay}" VerticalAlignment="Center" />
</StackPanel>
<StackPanel>
<Button x:Name="btnUpdate" Content="Update" VerticalAlignment="Center" HorizontalAlignment="Right" Click="btnUpdate_Click" Command="{Binding DataContext.updateProductionLineConfigCommand, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:production_line_config_home}}}" CommandParameter="{Binding ProductionLineConfig}"/>
</StackPanel>
</StackPanel>
</DataTemplate>
</DataGrid>
以下是我的ViewModel中的方法：
public ProductionLineConfig ProductionLineConfig
{
get { return productionlineconfig; }
set
{
productionlineconfig = value;
OnPropertyChanged("ProductionLineConfig");
}
}
这是我得到的错误消息：
System.Windows.Data错误：40：BindingExpression路径错误：'对象'''ProductionLineConfig'（HashCode = 47309994）'上找不到'ProductionLineConfig'属性。 BindingExpression：路径= ProductionLineConfig; DataItem ='ProductionLineConfig'（HashCode = 47309994）; target元素是'Button'（Name =''）; target属性是'CommandParameter'（类型'Object'）
我已将图像包含在我的应用程序here中
答案
根据您的代码源，我做了一个示例实现，以实现您的要求。
示例VM：
using System;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Runtime.CompilerServices;
using System.Windows;
namespace WpfApp5.ViewModels
{
public class ProductionLineConfigViewModel : INotifyPropertyChanged
{
public CustomCommand<ProductionLineConfig> UpdateCommand { get; }
public ProductionLineConfigViewModel()
{
PopulateProductionLineConfigs();
UpdateCommand = new CustomCommand<ProductionLineConfig>(UpdateConfig, (u) => true);
}
private ObservableCollection<ProductionLineConfig> _listAllProductionLineConfigs;
public ObservableCollection<ProductionLineConfig> listAllProductionLineConfigs
{
get { return _listAllProductionLineConfigs; }
set
{
_listAllProductionLineConfigs = value;
OnPropertyChanged();
}
}
// Call this from constructor.
private void PopulateProductionLineConfigs()
{
listAllProductionLineConfigs = new ObservableCollection<ProductionLineConfig>
{
new ProductionLineConfig
{
ProductionLineId = 1,
ProductionLineCode = "001",
ProductionLineCreatedDate = DateTime.Today.Date,
ProductionLineName = "safdsf",
ProductionLineStatus = true
},
new ProductionLineConfig
{
ProductionLineId = 1,
ProductionLineCode = "002",
ProductionLineCreatedDate = DateTime.Today.Date,
ProductionLineName = "sadfadfsdf",
ProductionLineStatus = true
}
};
}
private void UpdateConfig(ProductionLineConfig config)
{
MessageBox.Show("Line Name update: " + config.ProductionLineName);
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
public class ProductionLineConfig
{
public int ProductionLineId { get; set; }
public string ProductionLineCode { get; set; }
public string ProductionLineName { get; set; }
public bool ProductionLineStatus { get; set; }
public DateTime ProductionLineCreatedDate { get; set; }
}
}
示例XAML：
<Window x:Name="Root" x:Class="WpfApp5.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:viewModels="clr-namespace:WpfApp5.ViewModels"
mc:Ignorable="d"
Title="MainWindow" Height="450" Width="800">
<Window.DataContext>
<viewModels:ProductionLineConfigViewModel/>
</Window.DataContext>
<Grid Background="#FF006E8C">
<Grid.ColumnDefinitions>
<ColumnDefinition/>
<ColumnDefinition/>
<ColumnDefinition/>
<ColumnDefinition/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition/>
<RowDefinition/>
<RowDefinition/>
<RowDefinition/>
<RowDefinition/>
<RowDefinition/>
</Grid.RowDefinitions>
<Label Grid.ColumnSpan="4" Content="KAD ShopFloor System" HorizontalAlignment="Center" Margin="10" FontWeight="Bold" FontSize="30" FontFamily="Segoe UI" Foreground="White"/>
<Separator Grid.ColumnSpan="4" Grid.RowSpan="3" Background="White" Margin="0,-35,-0.4,39.2"/>
<DataGrid AutoGenerateColumns="False" Grid.Row="2" Grid.ColumnSpan="4" Grid.RowSpan="3" x:Name="productionLineConfigDataGrid" Margin="70,0.2,70,0"
ItemsSource="{Binding DataContext.listAllProductionLineConfigs, ElementName=Root}">
<DataGrid.Columns>
<DataGridTextColumn Header="ID" Binding="{Binding ProductionLineId, Mode=TwoWay}"/>
<DataGridTextColumn Header="Production Line Code" Binding="{Binding ProductionLineCode, Mode=TwoWay}"/>
<DataGridTextColumn Header="Production Line Name" Binding="{Binding ProductionLineName, Mode=TwoWay}"/>
<DataGridTextColumn Header="Status" Binding="{Binding ProductionLineStatus, Mode=TwoWay}"/>
<DataGridTextColumn Header="Created Date" Binding="{Binding ProductionLineCreatedDate, Mode=TwoWay}"/>
</DataGrid.Columns>
<DataGrid.RowDetailsTemplate>
<DataTemplate>
<Border BorderThickness="0" Background="BlanchedAlmond" Padding="10">
<StackPanel Orientation="Vertical" x:Name="stck">
<StackPanel Orientation="Horizontal">
<TextBlock FontSize="12" Text="ID: " VerticalAlignment="Center" />
<TextBlock x:Name="txtBlockLineId" FontSize="16" Foreground="MidnightBlue" Text="{Binding ProductionLineId, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" VerticalAlignment="Center" />
</StackPanel>
<StackPanel Orientation="Horizontal">
<TextBlock FontSize="12" Text="Line Code: " VerticalAlignment="Center" />
<TextBlock x:Name="txtBlockLineCode" FontSize="16" Foreground="MidnightBlue" Text="{Binding ProductionLineCode, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" VerticalAlignment="Center" />
</StackPanel>
<StackPanel Orientation="Horizontal">
<TextBlock FontSize="12" Text="Line Name: " VerticalAlignment="Center" />
<TextBox x:Name="txtLineName" FontSize="16" Foreground="MidnightBlue" Text="{Binding ProductionLineName, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" VerticalAlignment="Center" />
</StackPanel>
<!--<StackPanel Orientation="Horizontal">
<TextBlock FontSize="12" Text="Status: " VerticalAlignment="Center" />
<ComboBox ItemsSource="{Binding RelativeSource={RelativeSource FindAncestor,AncestorType={x:Type DataGrid}},
Path=DataContext.Statusstring}" SelectedValue="{Binding ProductionLineStatus, Converter={StaticResource statusToBooleanConverter}, Mode=TwoWay}" x:Name="cbProductionLineStatus" FlowDirection="LeftToRight" FontSize="16" Foreground="MidnightBlue"
HorizontalAlignment="Stretch" VerticalAlignment="Center"/>
</StackPanel>-->
<StackPanel>
<Button x:Name="btnUpdate" Content="Update" VerticalAlignment="Center" HorizontalAlignment="Right"
Command="{Binding DataContext.UpdateCommand, ElementName=Root}"
CommandParameter="{Binding}" />
</StackPanel>
</StackPanel>
以上是关于无法通过命令将值从视图传递到viewmodel的主要内容，如果未能解决你的问题，请参考以下文章
如何将值从 javascript 函数传递到 django 视图