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Backend API
<div class="form">
<div class="drive-panel">
<div class="drive-header dx-treeview-item"><div class="dx-treeview-item-content"><i class="dx-icon dx-icon-activefolder"></i><span>Drive C:</span></div></div>
@(Html.DevExtreme().Sortable()
.Filter(".dx-treeview-item")
.Data("driveC")
.Group("shared")
.AllowReordering(true)
.AllowDropInsideItem(true)
.OnDragChange("onDragChange")
.OnDragEnd("onDragEnd")
.Content(
Html.DevExtreme().TreeView()
.ID("treeviewDriveC")
.ExpandNodesRecursive(false)
.DataStructure(TreeViewDataStructure.Tree)
.KeyExpr("Id")
.ItemsExpr("Items")
.ExpandedExpr("IsExpanded")
.DisplayExpr("Name")
.DataSource(d => d.Mvc().LoadAction("GetHierarchicalDataForDragAndDrop"))
.DataSourceOptions(o => o.Map("mapIcons"))
.Width(250)
.Height(380).ToString()
))
</div>
<div class="drive-panel">
<div class="drive-header dx-treeview-item"><div class="dx-treeview-item-content"><i class="dx-icon dx-icon-activefolder"></i><span>Drive D:</span></div></div>
@(Html.DevExtreme().Sortable()
.Filter(".dx-treeview-item")
.Data("driveD")
.Group("shared")
.AllowReordering(true)
.AllowDropInsideItem(true)
.OnDragChange("onDragChange")
.OnDragEnd("onDragEnd")
.Content(
Html.DevExtreme().TreeView()
.ID("treeviewDriveD")
.ExpandNodesRecursive(false)
.DataStructure(TreeViewDataStructure.Tree)
.KeyExpr("Id")
.ItemsExpr("Items")
.ExpandedExpr("IsExpanded")
.ItemTemplate(@<text>
<div>
<i class="dx-icon dx-icon-<%- IsDirectory ? 'activefolder' : 'file' %>"></i><span><%-Name%></span>
</div>
</text>)
.Width(250)
.Height(380).ToString()
)
)
</div>
</div>
<script>
function onDragChange(e) {
if(e.fromComponent === e.toComponent) {
var $nodes = e.element.find(".dx-treeview-node");
var isDragIntoChild = $nodes.eq(e.fromIndex).find($nodes.eq(e.toIndex)).length > 0;
if(isDragIntoChild) {
e.cancel = true;
}
}
}
function onDragEnd(e) {
if(e.fromComponent === e.toComponent && e.fromIndex === e.toIndex) {
return;
}
var fromTreeView = getTreeView(e.fromData);
var toTreeView = getTreeView(e.toData);
var fromNode = findNode(fromTreeView, e.fromIndex);
var toNode = findNode(toTreeView, calculateToIndex(e));
if(e.dropInsideItem && toNode !== null && !toNode.itemData.IsDirectory) {
return;
}
var fromTopVisibleNode = getTopVisibleNode(fromTreeView);
var toTopVisibleNode = getTopVisibleNode(toTreeView);
var fromItems = fromTreeView.option('items');
var toItems = toTreeView.option('items');
moveNode(fromNode, toNode, fromItems, toItems, e.dropInsideItem);
fromTreeView.option("items", fromItems);
toTreeView.option("items", toItems);
fromTreeView.scrollToItem(fromTopVisibleNode);
toTreeView.scrollToItem(toTopVisibleNode);
}
function getTreeView(driveName) {
return driveName === 'driveC'
? $('#treeviewDriveC').dxTreeView('instance')
: $('#treeviewDriveD').dxTreeView('instance');
}
function calculateToIndex(e) {
if(e.fromComponent != e.toComponent || e.dropInsideItem) {
return e.toIndex;
}
return e.fromIndex >= e.toIndex
? e.toIndex
: e.toIndex + 1;
}
function findNode(treeView, index) {
var nodeElement = treeView.element().find('.dx-treeview-node')[index];
if(nodeElement) {
return findNodeById(treeView.getNodes(), nodeElement.getAttribute('data-item-id'));
}
return null;
}
function findNodeById(nodes, id) {
for(var i = 0; i < nodes.length; i++) {
if(nodes[i].itemData.Id == id) {
return nodes[i];
}
if(nodes[i].children) {
var node = findNodeById(nodes[i].children, id);
if(node != null) {
return node;
}
}
}
return null;
}
function moveNode(fromNode, toNode, fromItems, toItems, isDropInsideItem) {
var fromNodeContainingArray = getNodeContainingArray(fromNode, fromItems);
var fromIndex = findIndex(fromNodeContainingArray, fromNode.itemData.Id);
fromNodeContainingArray.splice(fromIndex, 1);
if(isDropInsideItem) {
toNode.itemData.Items.splice(toNode.itemData.Items.length, 0, fromNode.itemData);
} else {
var toNodeContainingArray = getNodeContainingArray(toNode, toItems);
var toIndex = toNode === null
? toItems.length
: findIndex(toNodeContainingArray, toNode.itemData.Id);
toNodeContainingArray.splice(toIndex, 0, fromNode.itemData);
}
}
function getNodeContainingArray(node, rootArray) {
return node === null || node.parent === null
? rootArray
: node.parent.itemData.Items;
}
function findIndex(array, id) {
var idsArray = array.map(function(elem) { return elem.Id; });
return idsArray.indexOf(id);
}
function getTopVisibleNode(component) {
var treeViewElement = component.element().get(0);
var treeViewTopPosition = treeViewElement.getBoundingClientRect().top;
var nodes = treeViewElement.querySelectorAll(".dx-treeview-node");
for(var i = 0; i < nodes.length; i++) {
var nodeTopPosition = nodes[i].getBoundingClientRect().top;
if(nodeTopPosition >= treeViewTopPosition) {
return nodes[i];
}
}
return null;
}
function mapIcons(item) {
if (item.Icon) {
item.icon = item.Icon;
}
if (item.Items) {
for (var i = 0; i < item.Items.length; i++) {
mapIcons(item.Items[i]);
}
}
return item;
}
</script>
using DevExtreme.AspNet.Data;
using DevExtreme.AspNet.Mvc;
using DevExtreme.NETCore.Demos.Models;
using DevExtreme.NETCore.Demos.Models.SampleData;
using Microsoft.AspNetCore.Mvc;
using Newtonsoft.Json;
using System.Collections.Generic;
using System.Linq;
namespace DevExtreme.NETCore.Demos.Controllers {
public class TreeViewController : Controller {
public ActionResult DragAndDropHierarchicalDataStructure() {
return View();
}
public object GetHierarchicalDataForDragAndDrop(DataSourceLoadOptions loadOptions) {
return Content(JsonConvert.SerializeObject(DataSourceLoader.Load(TreeViewHierarchicalDataForDragAndDrop.FileSystemItems, loadOptions)), "application/json");
}
}
}
using System.Collections.Generic;
namespace DevExtreme.NETCore.Demos.Models.TreeView {
public class FileSystemItem {
public string Id { get; set; }
public string ParentId { get; set; }
public string Name { get; set; }
public string Icon { get; set; }
public bool IsDirectory { get; set; }
public bool IsExpanded { get; set; }
public IEnumerable<FileSystemItem> Items { get; set; }
}
}
using System.Collections.Generic;
using DevExtreme.NETCore.Demos.Models.TreeView;
namespace DevExtreme.NETCore.Demos.Models.SampleData {
public static class TreeViewHierarchicalDataForDragAndDrop {
public static readonly IEnumerable<FileSystemItem> FileSystemItems = new[] {
new FileSystemItem {
Id = "1",
Name = "Documents",
Icon = "activefolder",
IsDirectory = true,
IsExpanded = true,
Items = new[] {
new FileSystemItem {
Id = "2",
Name = "Projects",
Icon = "activefolder",
IsDirectory = true,
IsExpanded = true,
Items = new[] {
new FileSystemItem {
Id = "3",
Name = "About.rtf",
Icon = "file",
IsDirectory = false
},
new FileSystemItem {
Id = "4",
Name = "Passwords.rtf",
Icon = "file",
IsDirectory = false
}
}
},
new FileSystemItem {
Id = "5",
Name = "About.xml",
Icon = "file",
IsDirectory = false
},
new FileSystemItem {
Id = "6",
Name = "Managers.rtf",
Icon = "file",
IsDirectory = false
},
new FileSystemItem {
Id = "7",
Name = "ToDo.txt",
Icon = "file",
IsDirectory = false
}
},
},
new FileSystemItem {
Id = "8",
Name = "Images",
Icon = "activefolder",
IsDirectory = true,
IsExpanded = true,
Items = new[] {
new FileSystemItem {
Id = "9",
Name = "logo.png",
Icon = "file",
IsDirectory = false
},
new FileSystemItem {
Id = "10",
Name = "banner.gif",
Icon = "file",
IsDirectory = false
}
}
},
new FileSystemItem {
Id = "11",
Name = "System",
Icon = "activefolder",
IsDirectory = true,
IsExpanded = true,
Items = new[] {
new FileSystemItem {
Id = "12",
Name = "Employees.txt",
Icon = "file",
IsDirectory = false
},
new FileSystemItem {
Id = "13",
Name = "PasswordList.txt",
Icon = "file",
IsDirectory = false
}
}
},
new FileSystemItem {
Id = "14",
Name = "Description.rtf",
Icon = "file",
IsDirectory = false
},
new FileSystemItem {
Id = "15",
Name = "Description.txt",
Icon = "file",
IsDirectory = false
}
};
}
}
.form {
display: flex;
}
.form>div {
display: inline-block;
vertical-align: top;
}
.dx-treeview-item {
box-sizing: border-box;
}
.drive-header {
min-height: auto;
padding: 0px;
cursor: default;
margin-bottom: 10px;
}
.drive-panel {
padding: 20px 30px;
font-size: 115%;
font-weight: bold;
border-right: 1px solid rgba(165, 165, 165, 0.4);
height: 100%;
}
.drive-panel:last-of-type {
border-right: none;
}
Use Sortable to implement the necessary drag and drop functionality within your web app. The following steps outline configuration requirements for our TreeView:
-
Allow users to reorder nodes
Wrap the TreeView in a Sortable and enable the Sortable's allowReordering property. -
Allow users to change node hierarchy
Enable the allowDropInsideItem property so that users can drop one node onto another. This adds it as the target node's child. If this property is disabled, users can only drop nodes between other nodes. -
Allow users to drag only tree view nodes
To specify tree view nodes as drag targets, set the filter property to a class selector. Since all tree view nodes use thedx-treeview-nodeclass, you can use this class selector as needed. -
Prevent a node from being moved into its child node
When a user moves a parent node into its own child node, it breaks the hierarchy. To prevent this outcome, implement the onDragChange function and traverse up the node tree. If the target is a child of the dragged node,cancelthe ability to drop the node. -
Reorder nodes in code
Implement the onDragEnd function. In this function, you must gather information about nodes being moved. With this information, you can reorder the nodes in the data source (see themoveNodefunction), and reassign the data source to the TreeView's items property. -
Specify tree view identifiers (for drag and drop between multiple tree views only)
Identifiers help distinguish between multiple tree views. Save them in the Sortable's data property. The tree views below include the following identifiers: "driveC" and "driveD". -
Combine tree views into one drag and drop group (for drag and drop between multiple tree views only)
Set the Sortable's group property to the same value for all tree views. This allows users to move nodes between the tree views.