C# WPF MVVMLight从文本框中的数据网格中获取所选项目。

Question

我遇到了一个大问题，要从 Datagrid selected row 用户选择一行，视图就会从特定的文本框中获取该行的值。然后用户可以在文本框内进行修改并更新数据库。在Youtube和Google上看了几个小时的教程后，我仍然不知道如何才能达到这个目的（从文本框中选择的行中获取值）。请帮助我

以下是View和ViewModel的代码。

UserControl:

<!--Database datagrid-->
        <materialDesign:Card Margin="5">
            <DataGrid x:Name="MachineDataGrid" AutoGenerateColumns="False" MaxHeight="750" VerticalScrollBarVisibility="Auto" HorizontalScrollBarVisibility="Auto" ItemsSource="{Binding DataContext}">

                <DataGrid.Columns>
                    <materialDesign:DataGridTextColumn Header="{x:Static language:Lang.DgMachineID}" Binding="{Binding MachineID, Mode=TwoWay}"/>
                    <materialDesign:DataGridTextColumn Header="{x:Static language:Lang.DgCustomerId}" Binding="{Binding CustomerID}"/>
                    <materialDesign:DataGridTextColumn Header="{x:Static language:Lang.DgCustomerName}" Binding="{Binding CustomerName}"/>
                    <materialDesign:DataGridTextColumn Header="{x:Static language:Lang.DgCity}" Binding="{Binding City}"/>
                    <materialDesign:DataGridTextColumn Header="{x:Static language:Lang.DgCountry}" Binding="{Binding Country}"/>
                    <materialDesign:DataGridTextColumn Header="{x:Static language:Lang.DgSpindleC1}" Binding="{Binding SpindleC1}"/>
                    <materialDesign:DataGridTextColumn Header="{x:Static language:Lang.DgSpindleC2}" Binding="{Binding SpindleC2}"/>
                    <materialDesign:DataGridTextColumn Header="{x:Static language:Lang.DgHoningHead}" Binding="{Binding HoningHead}"/>
                    <materialDesign:DataGridTextColumn Header="{x:Static language:Lang.DgNCVersion}" Binding="{Binding NCVersion}"/>
                    <materialDesign:DataGridTextColumn Header="{x:Static language:Lang.DgHMIVersion}" Binding="{Binding HMIVersion}"/>
                    <materialDesign:DataGridTextColumn Header="{x:Static language:Lang.DgHRIVersion}" Binding="{Binding HRIVersion}"/>
                    <materialDesign:DataGridTextColumn Header="{x:Static language:Lang.DgAHSVersion}" Binding="{Binding AHSVersion}"/>
                </DataGrid.Columns>
            </DataGrid>
        </materialDesign:Card>

ViewModel:

 //Operation button for save, update, delete and print
    public ICommand SaveCommand { get; private set; }
    public ICommand UpdateCommand { get; private set; }
    public ICommand DeleteCommand { get; private set; }
    public ICommand PrintCommand { get; private set; }
    public ICommand ShowAdvCommand { get; private set; }


    public ObservableCollection<Machine> DataContext { get; set; }
    public Machine MachineSelectedItem { get; set; }
    public object MachineDataGrid { get; private set; }

    //Datagrid string

    //PRWContext for general use
    private PRWContext context = new PRWContext();

    public MachineViewModel()
    {
        //Commands for save, update, delete and print
        SaveCommand = new RelayCommand(() => ExecuteSaveCommand());
        UpdateCommand = new RelayCommand(() => ExecuteUpdateCommand());
        DeleteCommand = new RelayCommand(() => ExecuteDeleteCommand());
        PrintCommand = new RelayCommand(() => ExecutePrintCommand());


        ////Load the data from PRW Database to datagrid
        LoadData();
    }

    private void ExecuteSaveCommand()
    {
        Machine machine = new Machine
        {
            //Machine data
            MachineID = MachineID,
            CustomerID = CustomerID,
            CustomerName = CustomerName,
            City = City,
            Country = Country,

            //Serial data
            SpindleC1 = SpindleC1,
            SpindleC2 = SpindleC2,
            HoningHead = HoningHead,

            //Softwareversion data
            NCVersion = NCVersion,
            HMIVersion = HMIVersion,
            HRIVersion = HRIVersion,
            AHSVersion = AHSVersion
        };

        context.Machines.Add(machine);
        context.SaveChanges();

        ClearText();
    }

    private void ExecuteUpdateCommand()
    {
        Machine machine = context.Machines.FirstOrDefault(w => w.MachineID == MachineID);

        machine.CustomerID = CustomerID;
        machine.CustomerName = CustomerName;

        context.SaveChanges();
        ClearText();
    }

    private void ExecuteDeleteCommand()
    {
        throw new NotImplementedException();
    }

    private void ExecutePrintCommand()
    {
        throw new NotImplementedException();
    }

    //Load data from database to grid
    private void LoadData()
    {
        context.Machines.Load();
        this.DataContext = context.Machines.Local;
    }

    //Clear textboxes
    private void ClearText()
    {
        MachineID = string.Empty;
        CustomerID = string.Empty;
        CustomerName = string.Empty;
        City = string.Empty;
        Country = string.Empty;
        SpindleC1 = string.Empty;
        SpindleC2 = string.Empty;
        HoningHead = string.Empty;
        NCVersion = string.Empty;
        HMIVersion = string.Empty;
        HRIVersion = string.Empty;
        AHSVersion = string.Empty;
    }

我试着用 eventrigger for selectionchanged 命令和其他问题中看到的几种不同的方法来做，但我很不走运 :(

Answer 1

我认为你缺少了一点，你必须做什么才能得到这些值。选定项目.

正如你所做的，你需要绑定（在你的XAML代码中）你的 数据网格 对你的 项目来源. 但是，你也可以使用属性 选择项目

所以，你最终会有这样的东西。(我只是包括了重要的部分)

<DataGrid ItemsSource="{Binding DataContext}"  SelectedItem="{Binding Path=MachineSelectedItem }"/>

你可以得到进一步的解释 在此答案上 但我已经把它应该希望做的伎俩;)

Answer 2

一些小时前，我发现了我的代码的问题;)我不得不插入以下代码在我的ViewModel。

 private Machine machineSelectedItem;
    public Machine MachineSelectedItem
    {
        get { return machineSelectedItem; }
        set { machineSelectedItem = value; OnPropertyChanged(); }
    }

Command for SelectionChanged:

public ICommand SelectionChangedCommand { get; set; }` SelectionChangedCommand = new RelayCommand(() => ExecuteSelectionChangedCommand());` private void ExecuteSelectionChangedCommand()
    {
        **MachineID = machineSelectedItem.MachineID ? .ToString() ?? "";
        CustomerID = machineSelectedItem.CustomerID ? .ToString() ?? "";**
    }

并在视图中插入以下代码。

<DataGrid x:Name="MachineDataGrid" AutoGenerateColumns="False" MaxHeight="750" VerticalScrollBarVisibility="Auto" HorizontalScrollBarVisibility="Auto" ItemsSource="{Binding DataContext, Mode=TwoWay}" SelectedItem="{Binding Path=MachineSelectedItem, Mode=TwoWay}">
                <ie:Interaction.Triggers>
                    <ie:EventTrigger EventName="SelectionChanged">
                        <ie:InvokeCommandAction Command="{Binding SelectionChangedCommand}"  CommandParameter="{Binding ElementName=MachineDataGrid, Path=SelectedItem}"/>
                    </ie:EventTrigger>
                </ie:Interaction.Triggers>

这就完成了我所需要的工作。也许它是一个丑陋的解决方案，但我不关心的时刻。