Viewer.cshtml

<script type = "text/html" id = "employeeID-custom-editor" >
<div data-bind="dxTreeList: { dataSource: data, columns: columns, showBorders: true,
         selection:{mode: 'single'}, onSelectionChanged: onTreeListSelectionChanged, 
         onInitialized: onTreeListInitialized}"> 
    </div>
</script>

<script type="text/javascript">
    // Specifies the endpoint for the tree list data.
    var data = window.location.protocol + "//" + window.location.host + "/Home/ListEmployees";
    // Specifies the columns to display in the tree list.
    var columns = [{ dataField: "name", caption: "Name" }, { dataField: "title", caption: "Title" }];

    var p_employeeID_editor;
    var parametersModel;

    function customizeParameterEditors(s, e) {
        if (e.parameter.type === 'System.DateTime') {
            e.info.editor = $.extend({}, e.info.editor);
            e.info.editor.extendedOptions =
                $.extend(e.info.editor.extendedOptions || {},
                    { type: 'date' }, { displayFormat: 'dd-MMM-yyyy' });
            var validationRule = {
                type: "range",
                min: new Date(2000, 0, 1),
                message: "We do not retain data prior to the year 2000."
            };
            e.info.validationRules = [validationRule];
        };
        if (e.parameter.name == "p_employeeID") {
            e.info.editor = { header: 'employeeID-custom-editor' };
        };
    };
    function onTreeListInitialized(e) {
        p_employeeID_editor = e.component;
    }
    function onTreeListSelectionChanged(e) {
        if (e.selectedRowsData.length > 0) {
            var selectedEmployeeID = e.selectedRowsData[0].id;
            parametersModel.p_employeeID = selectedEmployeeID;
        }
    };
    function onParametersReset(s, e) {
        p_employeeID_editor.deselectAll();
    };
    function onBeforeRender(s, e) {
        e.tabPanel.width = 500;
        parametersModel = e.parametersModel;
    };
</script>

@Html.DevExpress().WebDocumentViewer(settings =>
{
    settings.Name = "WebDocumentViewer1";
    settings.ClientSideEvents.BeforeRender = "onBeforeRender";
    settings.ClientSideEvents.CustomizeParameterEditors = "customizeParameterEditors";
    settings.ClientSideEvents.ParametersReset = "onParametersReset";
}).Bind("TestReport").GetHtml()