MVVM中的ReportViewer

Question

我正在使用Visual 2015构建一个应用程序。该应用程序需要在本地显示一些报告。

有以下两种解决办法：

• MS ReportViewer在WPF中的应用
• 演练:在WPF应用程序中使用ReportViewer

虽然第一个是MVVM，但它将UI与视图模型混合在一起。第二种是纯代码隐藏。

下面是第一个例子所暗示的：

WindowsFormsHost windowsFormsHost = new WindowsFormsHost();
reportViewer = new ReportViewer();
windowsFormsHost.Child = reportViewer;
this.Viewer = windowsFormsHost

注意，ReportViewer是一个UI控件。第二种解决方案使用代码隐藏文件：

private void ReportViewer_Load(object sender, EventArgs e)
{
   //...
}

是否有方法将本地SSRS报告嵌入WPF应用程序并遵循良好的MVVM实践？谢谢。

更新：不需要狂热！如果需要代码隐藏，我不介意。

Answer 1

我们使用视图从ComboBox中选择报表，并使用按钮运行报表。在视图模型中，报表的ComboBox绑定到报表名称和ID的ObservableCollection。然后，我们使用MVVM轻型工具包的Messaging类发送/接收“消息”。注意，基本视图模型MyAppViewModelBase继承了Light的ViewModelBase，后者定义了RaisePropertyChanged()。

还请注意，我们可以传递所选报表的VM，而不是视图的VM；这将更有效，但需要对此代码进行修改。然后，我们将为所有报表VM使用一个基类，并在代码隐藏中使用模式匹配开关来选择要运行的报表。

以下是视图模型的相关代码：

using GalaSoft.MvvmLight.Messaging;

public class ReportsViewModel : MyAppViewModelBase
{
    public ReportsViewModel()
    {
        // Register a listener that receives the enum of the 
        // report that's ready. The message it receives has 
        // name "SsrsReportReady" with handler SsrsReportReady.
        Messenger.Default.Register<Constants.Report>(this, "SsrsReportReady", SsrsReportReady);

        // Other logic...
    }

    // Bound to a button to run the selected report
    public ICommand RunReportRelayCommand =>
                new RelayCommand(RunReport);

    // Backing field for the selected report.
    private ReportViewModel _selectedReportVm;

    public ReportViewModel SelectedReportVm
    {
        get { return _selectedReportVm; }
        set
        {
            if (Equals(value, _selectedReportVm)) return;
            _selectedReportVm = value;

            // Built-in method from Light Toolkit to 
            // handle INotifyPropertyChanged
            RaisePropertyChanged();  
        }
    }

    private void RunReport()
    {
        // Send a message called "RunSSRSReport" with this VM attached as its data.
        Messenger.Default.Send(this, "RunSSRSReport");
    }

    // Handler for report-ready
    private void SsrsReportReady(Constants.Report obj)
    {
        ShowReport = true;
        IsRunReportButtonEnabled = true;
        RunReportButtonContent = Constants.BtnGenerateReport;

        // View uses Material Design's Expander control.
        // We expand/collapse sections of the view.
        ExpandReport = true;
        ExpandParameters = false;
    }
}

在视图的代码背后：

using GalaSoft.MvvmLight.Messaging;

public partial class ReportsView : UserControl
{
    public ReportsView()
    {
        InitializeComponent();

        // Register a listener for the "RunSSRSReport" 
        // message, called from our viewmodel. Its 
        // handler is RunSsrsReport and its data type 
        // is ReportsViewModel.
        Messenger.Default.Register<ReportsViewModel>(this, "RunSSRSReport", RunSsrsReport);

        DataContext = new ReportsViewModel();
    }

    // Handler to run the selected report. 
    private void RunSsrsReport(ReportsViewModel obj)
    {
        // Basic validation
        if (obj.SelectedReportVm == null || obj.SelectedReportVm.Id.Equals(-1)) 
        {
            return;
        }

        // Ugly switch to run the correct report.
        // It can be re-written with pattern matching.
        switch (obj.SelectedReportVm.Id)
        {
            case (int)Constants.Report.ReportA:
                RunReportA(obj);
                break;
            case (int)Constants.Report.ReportB:
                RunReportB(obj);
                break;
            // other reports....
        }
    }   

    // Run the report using dataset and tableadapter.
    // Modify to use your code for running the report.
    private void RunReportA(ReportsViewModel reportsViewModel)
    {
        var dataSet = new ReportADataSet();
        dataSet.BeginInit();

        // We reference the ReportViewer control in XAML.
        ReportViewer.ProcessingMode = ProcessingMode.Local;
        ReportViewer.LocalReport.ShowDetailedSubreportMessages = true;
        ReportViewer.LocalReport.DataSources.Clear();
        var dataSource = new ReportDataSource
        {
            Name = "ReportA_DS",
            Value = dataSet.uspReportA  // Uses a stored proc
        };
        ReportViewer.LocalReport.DataSources.Add(dataSource);
        ReportViewer.LocalReport.ReportEmbeddedResource =
            "MyApp.Reports.ReportA.rdlc";
        dataSet.EndInit();
        new reportATableAdapter { ClearBeforeFill = true }
            .Fill(dataSet.uspReportA);

        // Send message back to viewmodel that the report is ready.
        Messenger.Default.Send(Constants.Report.ReportA, "SsrsReportReady");
    }
}

report视图有一个名称为WindowsFormsHost的ReportViewer，在上面的代码隐藏中引用：

<WindowsFormsHost Width="Auto" Height="500">                   
    <rv:ReportViewer x:Name="ReportViewer" />
</WindowsFormsHost>