MainWindow.xaml

<dx:ThemedWindow x:Class="PassDataFromViewModelToReport.MainWindow"
                 xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                 xmlns:dxmvvm="http://schemas.devexpress.com/winfx/2008/xaml/mvvm"
                 xmlns:dx="http://schemas.devexpress.com/winfx/2008/xaml/core"
                 xmlns:dxp="http://schemas.devexpress.com/winfx/2008/xaml/printing"
                 xmlns:dxg="http://schemas.devexpress.com/winfx/2008/xaml/grid"
                 xmlns:models="clr-namespace:PassDataFromViewModelToReport.Models"
                 Title="MainWindow" Height="450" Width="800">
    <dx:ThemedWindow.DataContext>
        <models:MainViewModel />
    </dx:ThemedWindow.DataContext>
    
    <dxmvvm:Interaction.Behaviors>
        <dx:DialogService>
            <dx:DialogService.ViewTemplate>
                <DataTemplate>
                    <dxp:DocumentPreviewControl RequestDocumentCreation="True"
                                                DocumentSource="{Binding Report}" />
                </DataTemplate>
            </dx:DialogService.ViewTemplate>
        </dx:DialogService>
    </dxmvvm:Interaction.Behaviors>

    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition />
            <RowDefinition Height="auto" />
        </Grid.RowDefinitions>
        <dxg:GridControl ItemsSource="{Binding Employees}"
                         SelectedItem="{Binding SelectedEmployee, Mode=TwoWay}"
                         SelectionMode="Row"
                         AutoGenerateColumns="AddNew"
                         Margin="12,12,12,0">
            <dxg:GridControl.View>
                <dxg:TableView AllowEditing="False" />
            </dxg:GridControl.View>
        </dxg:GridControl>
        <Button Content="Show Preview" Command="{Binding ShowPrintPreviewCommand}" 
                Grid.Row="1" Margin="12" />
    </Grid>
</dx:ThemedWindow>