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Drop Down Box

Single Selection

The DropDownBox UI component is an editor that consists of a text field and drop-down content. In this demo, the content is the TreeView and the DataGrid in the single selection mode.

The following instructions show how to synchronize the DropDownBox with any other embedded DevExtreme UI component:

  1. Specify data sources
    The DropDownBox's and embedded UI component's data sources can be the same or different. If they are different, the UI component's key field should be present in the DropDownBox's data source.

  2. Specify which data field provides the DropDownBox's values and the embedded UI component's keys
    Assign the field's name to the DropDownBox's valueExpr property and to the key property of the embedded UI component's store.

  3. Synchronize the DropDownBox's value and the embedded UI component's selection

    1. Select data items according to the DropDownBox's initial value. To do this, assign the value to the embedded UI component's selectedRowKeys/selectedItemKeys property (see the example with the DataGrid below). If the UI component does not have such properties, implement the onContentReady handler (the example with the TreeView).
    2. Implement the DropDownBox's onValueChanged handler to update the selection when the value changes.
    3. Implement the embedded UI component's onSelectionChanged handler to update the DropDownBox's value when the selection changes.
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window.onload = function() { var treeView; var syncTreeViewSelection = function(treeView, value){ if (!treeView) return; if (!value) { treeView.unselectAll(); } else { treeView.selectItem(value); } }; var makeAsyncDataSource = function(jsonFile){ return new{ loadMode: "raw", key: "ID", load: function() { return $.getJSON("../../../../data/" + jsonFile); } }); }; var getSelectedItemsKeys = function(items) { var result = []; items.forEach(function(item) { if(item.selected) { result.push(item.key); } if(item.items.length) { result = result.concat(getSelectedItemsKeys(item.items)); } }); return result; }; var treeDataSource = makeAsyncDataSource("treeProducts.json"), gridDataSource = makeAsyncDataSource("customers.json"); var treeBoxOptions = { value: ko.observable("1_1"), valueExpr: "ID", displayExpr: "name", placeholder: "Select a value...", showClearButton: true, dataSource: treeDataSource, treeView: { dataSource: treeDataSource, dataStructure: "plain", keyExpr: "ID", parentIdExpr: "categoryId", selectionMode: "single", onContentReady: function(e) { treeView = e.component; syncTreeViewSelection(treeView, treeBoxOptions.value()); }, onItemSelectionChanged: function(args){ var nodes = args.component.getNodes(), value = getSelectedItemsKeys(nodes); treeBoxOptions.value(value); }, displayExpr: "name", selectByClick: true, selectNodesRecursive: false } }; var gridBoxValue = ko.observable(3); var gridBoxOptions = { value: gridBoxValue, valueExpr: "ID", deferRendering: false, placeholder: "Select a value...", displayExpr: function(item){ return item && item.CompanyName + " <" + item.Phone + ">"; }, showClearButton: true, dataSource: gridDataSource, dataGrid: { dataSource: gridDataSource, columns: ["CompanyName", "City", "Phone"], hoverStateEnabled: true, paging: { enabled: true, pageSize: 10 }, filterRow: { visible: true }, scrolling: { mode: "infinite" }, selection: { mode: "single" }, height: "100%", selectedRowKeys: ko.computed(function(){ var editorValue = gridBoxValue(); return (editorValue && [editorValue]) || []; }), onSelectionChanged: function(selectedItems){ var hasSelection = selectedItems.selectedRowKeys.length; gridBoxValue(hasSelection ? selectedItems.selectedRowKeys[0] : null); } } }; ko.computed(function(){ syncTreeViewSelection(treeView, treeBoxOptions.value()); }); var viewModel = { treeBoxOptions: treeBoxOptions, gridBoxOptions: gridBoxOptions }; ko.applyBindings(viewModel, document.getElementById("dropdown-box-demo")); };
<!DOCTYPE html> <html xmlns=""> <head> <title>DevExtreme Demo</title> <meta http-equiv="X-UA-Compatible" content="IE=edge"/> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0"/> <script src=""></script> <script>window.jQuery || document.write(decodeURIComponent('%3Cscript src="js/jquery.min.js"%3E%3C/script%3E'))</script> <script src=""></script> <link rel="stylesheet" type="text/css" href=""/> <link rel="stylesheet" type="text/css" href=""/> <script src=""></script> <link rel="stylesheet" type="text/css" href="styles.css"/> <script src="index.js"></script> </head> <body class="dx-viewport"> <div class="demo-container"> <div id="dropdown-box-demo" class="form"> <div class="dx-fieldset"> <div class="dx-field"> <div class="dx-field-label">DropDownBox with embedded TreeView</div> <div class="dx-field-value"> <div data-bind="dxDropDownBox: treeBoxOptions"> <div data-options="dxTemplate: { name: 'content' }"> <div data-bind="dxTreeView: treeBoxOptions.treeView"></div> </div> </div> </div> </div> <div class="dx-field"> <div class="dx-field-label">DropDownBox with embedded DataGrid</div> <div class="dx-field-value"> <div data-bind="dxDropDownBox: gridBoxOptions"> <div data-options="dxTemplate: { name: 'content' }"> <div data-bind="dxDataGrid: gridBoxOptions.dataGrid"></div> </div> </div> </div> </div> </div> </div> </div> </body> </html>
.form .dx-fieldset { height: 500px; }