Single Selection
Documentation
The DropDownBox widget is an editor that consists of a text field and drop-down content. The content can be anything. In this demo, it is the TreeView widget and the DataGrid widget. This demo also illustrates how to implement single selection and how to synchronize the DropDownBox with the nested widgets.
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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");
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="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/3.4.1/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/19.1.5/css/dx.common.css"/>
<link rel="stylesheet" type="text/css" href="https://cdn3.devexpress.com/jslib/19.1.5/css/dx.light.css"/>
<script src="https://cdn3.devexpress.com/jslib/19.1.5/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;
}