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Drop Down Box

Single Selection

The DropDownBox 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 component:

  1. Specify data sources
    The DropDownBox's and embedded component's data sources can be the same or different. If they are different, the embedded 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 component's keys
    Assign the field's name to the DropDownBox's valueExpr property and to the key property of the embedded component's store.

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

    1. Select data items according to the DropDownBox's initial value. To do this, assign the value to the embedded component's selectedRowKeys/selectedItemKeys property (see the example with the DataGrid below). If the embedded 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 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 DevExpress.data.CustomStore({ 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"), isTreeBoxOpened = ko.observable(false); var treeBoxOptions = { value: ko.observable("1_1"), valueExpr: "ID", opened: isTreeBoxOpened, 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); }, onItemClick: function(){ isTreeBoxOpened(false); }, displayExpr: "name", selectByClick: true, selectNodesRecursive: false } }; var gridBoxValue = ko.observable(3), isGridBoxOpened = ko.observable(false); var gridBoxOptions = { value: gridBoxValue, opened: isGridBoxOpened, 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: "virtual" }, 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); isGridBoxOpened(false); } } }; 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="http://www.w3.org/1999/xhtml"> <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="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script> <script>window.jQuery || document.write(decodeURIComponent('%3Cscript src="js/jquery.min.js"%3E%3C/script%3E'))</script> <script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.4.2/knockout-min.js"></script> <link rel="stylesheet" type="text/css" href="https://cdn3.devexpress.com/jslib/21.1.4/css/dx.common.css"/> <link rel="stylesheet" type="text/css" href="https://cdn3.devexpress.com/jslib/21.1.4/css/dx.light.css"/> <script src="https://cdn3.devexpress.com/jslib/21.1.4/js/dx.all.js"></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; }
[{ "ID": 1, "CompanyName": "Premier Buy", "Address": "7601 Penn Avenue South", "City": "Richfield", "State": "Minnesota", "Zipcode": 55423, "Phone": "(612) 291-1000", "Fax": "(612) 291-2001", "Website": "http://www.nowebsitepremierbuy.com" }, { "ID": 2, "CompanyName": "ElectrixMax", "Address": "263 Shuman Blvd", "City": "Naperville", "State": "Illinois", "Zipcode": 60563, "Phone": "(630) 438-7800", "Fax": "(630) 438-7801", "Website": "http://www.nowebsiteelectrixmax.com" }, { "ID": 3, "CompanyName": "Video Emporium", "Address": "1201 Elm Street", "City": "Dallas", "State": "Texas", "Zipcode": 75270, "Phone": "(214) 854-3000", "Fax": "(214) 854-3001", "Website": "http://www.nowebsitevideoemporium.com" }, { "ID": 4, "CompanyName": "Screen Shop", "Address": "1000 Lowes Blvd", "City": "Mooresville", "State": "North Carolina", "Zipcode": 28117, "Phone": "(800) 445-6937", "Fax": "(800) 445-6938", "Website": "http://www.nowebsitescreenshop.com" }, { "ID": 5, "CompanyName": "Braeburn", "Address": "1 Infinite Loop", "City": "Cupertino", "State": "California", "Zipcode": 95014, "Phone": "(408) 996-1010", "Fax": "(408) 996-1012", "Website": "http://www.nowebsitebraeburn.com" }, { "ID": 6, "CompanyName": "PriceCo", "Address": "30 Hunter Lane", "City": "Camp Hill", "State": "Pennsylvania", "Zipcode": 17011, "Phone": "(717) 761-2633", "Fax": "(717) 761-2334", "Website": "http://www.nowebsitepriceco.com" }, { "ID": 7, "CompanyName": "Ultimate Gadget", "Address": "1557 Watson Blvd", "City": "Warner Robbins", "State": "Georgia", "Zipcode": 31093, "Phone": "(995) 623-6785", "Fax": "(995) 623-6786", "Website": "http://www.nowebsiteultimategadget.com" }, { "ID": 8, "CompanyName": "EZ Stop", "Address": "618 Michillinda Ave.", "City": "Arcadia", "State": "California", "Zipcode": 91007, "Phone": "(626) 265-8632", "Fax": "(626) 265-8633", "Website": "http://www.nowebsiteezstop.com" }, { "ID": 9, "CompanyName": "Clicker", "Address": "1100 W. Artesia Blvd.", "City": "Compton", "State": "California", "Zipcode": 90220, "Phone": "(310) 884-9000", "Fax": "(310) 884-9001", "Website": "http://www.nowebsiteclicker.com" }, { "ID": 10, "CompanyName": "Store of America", "Address": "2401 Utah Ave. South", "City": "Seattle", "State": "Washington", "Zipcode": 98134, "Phone": "(206) 447-1575", "Fax": "(206) 447-1576", "Website": "http://www.nowebsiteamerica.com" }, { "ID": 11, "CompanyName": "Zone Toys", "Address": "1945 S Cienega Boulevard", "City": "Los Angeles", "State": "California", "Zipcode": 90034, "Phone": "(310) 237-5642", "Fax": "(310) 237-5643", "Website": "http://www.nowebsitezonetoys.com" }, { "ID": 12, "CompanyName": "ACME", "Address": "2525 E El Segundo Blvd", "City": "El Segundo", "State": "California", "Zipcode": 90245, "Phone": "(310) 536-0611", "Fax": "(310) 536-0612", "Website": "http://www.nowebsiteacme.com" }]
[ { "ID": 1, "name": "Stores", "expanded": true }, { "ID": "1_1", "categoryId": 1, "name": "Super Mart of the West", "expanded": true }, { "ID": "1_1_1", "categoryId": "1_1", "name": "Video Players" }, { "ID": "1_1_1_1", "categoryId": "1_1_1", "name": "HD Video Player", "price": 220 }, { "ID": "1_1_1_2", "categoryId": "1_1_1", "name": "SuperHD Video Player", "price": 270 }, { "ID": "1_1_2", "categoryId": "1_1", "name": "Televisions", "expanded": true }, { "ID": "1_1_2_1", "categoryId": "1_1_2", "name": "SuperLCD 42", "price": 1200 }, { "ID": "1_1_2_2", "categoryId": "1_1_2", "name": "SuperLED 42", "price": 1450 }, { "ID": "1_1_2_3", "categoryId": "1_1_2", "name": "SuperLED 50", "price": 1600 }, { "ID": "1_1_2_4", "categoryId": "1_1_2", "name": "SuperLCD 55", "price": 1750 }, { "ID": "1_1_2_5", "categoryId": "1_1_2", "name": "SuperLCD 70", "price": 4000 }, { "ID": "1_1_3", "categoryId": "1_1", "name": "Monitors" }, { "ID": "1_1_3_1", "categoryId": "1_1_3", "name": "19\"" }, { "ID": "1_1_3_1_1", "categoryId": "1_1_3_1", "name": "DesktopLCD 19", "price": 160 }, { "ID": "1_1_4", "categoryId": "1_1", "name": "Projectors" }, { "ID": "1_1_4_1", "categoryId": "1_1_4", "name": "Projector Plus", "price": 550 }, { "ID": "1_1_4_2", "categoryId": "1_1_4", "name": "Projector PlusHD", "price": 750 } ]