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:
-
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. -
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. -
Synchronize the DropDownBox's value and the embedded component's selection
- 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).
- Implement the DropDownBox's onValueChanged handler to update the selection when the value changes.
- Implement the embedded component's onSelectionChanged handler to update the DropDownBox's value when the selection changes.
Feel free to share demo-related thoughts here.
If you have technical questions, please create a support ticket in the DevExpress Support Center.
If you have technical questions, please create a support ticket in the DevExpress Support Center.
Thank you!
We appreciate your feedback.
We appreciate your feedback.
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/20.2.6/css/dx.common.css"/>
<link rel="stylesheet" type="text/css" href="https://cdn3.devexpress.com/jslib/20.2.6/css/dx.light.css"/>
<script src="https://cdn3.devexpress.com/jslib/20.2.6/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;
}