@minoru/react-dnd-treeview

A draggable / droppable React-based treeview component. You can use render props to create each node freely.

Usage no npm install needed!

<script type="module">
  import minoruReactDndTreeview from 'https://cdn.skypack.dev/@minoru/react-dnd-treeview';
</script>

README

React DnD TreeView

A draggable / droppable React-based treeview component.
You can use render props to create each node freely.

react-dnd-treeview

Demo

Examples (on CodeSandbox)

Some of the examples below use Material-UI components, but TreeView does not depend on Material-UI, so you can use other libraries or your own custom components.

Getting Started

Installation

$ npm install --save @minoru/react-dnd-treeview

Usage

import { useState } from "react";
import { Tree } from "@minoru/react-dnd-treeview";
import initialData from "./sample.json";

function App() {
  const [treeData, setTreeData] = useState(initialData);
  const handleDrop = (newTreeData) => setTreeData(newTreeData);

  return (
    <Tree
      tree={treeData}
      rootId={0}
      onDrop={handleDrop}
      render={(node, { depth, isOpen, onToggle }) => (
        <div style={{ marginLeft: depth * 10 }}>
          {node.droppable && (
            <span onClick={onToggle}>{isOpen ? "[-]" : "[+]"}</span>
          )}
          {node.text}
        </div>
      )}
    />
  );
}

Data Structure

To display the treeview, pass data with the following structure to the tree property of the Tree component.

Basic example

The minimal data structure for representing the tree is shown in the following example

[
  {
    "id": 1,
    "parent": 0,
    "droppable": true,
    "text": "Folder 1"
  },
  {
    "id": 2,
    "parent": 1,
    "text": "File 1-1"
  },
  {
    "id": 3,
    "parent": 1,
    "text": "File 1-2"
  },
  {
    "id": 4,
    "parent": 0,
    "droppable": true,
    "text": "Folder 2"
  },
  {
    "id": 5,
    "parent": 4,
    "droppable": true,
    "text": "Folder 2-1"
  },
  {
    "id": 6,
    "parent": 5,
    "text": "File 2-1-1"
  }
]

Optional data

If you want to pass custom properties to each node's rendering,
you can use the data property.

[
  {
    "id": 1,
    "parent": 0,
    "droppable": true,
    "text": "Folder 1"
  },
  {
    "id": 2,
    "parent": 1,
    "text": "File 1-1",
    "data": {
      "fileType": "csv",
      "fileSize": "0.5MB"
    }
  },
  {
    "id": 3,
    "parent": 1,
    "text": "File 1-2",
    "data": {
      "fileType": "pdf",
      "fileSize": "4.8MB"
    }
  },
  {
    "id": 4,
    "parent": 0,
    "droppable": true,
    "text": "Folder 2"
  },
  {
    "id": 5,
    "parent": 4,
    "droppable": true,
    "text": "Folder 2-1"
  },
  {
    "id": 6,
    "parent": 5,
    "text": "File 2-1-1",
    "data": {
      "fileType": "image",
      "fileSize": "2.1MB"
    }
  }
]

Node Properties

Key Type Required Default Description
id number | string yes - Identifier of each node
parent number | string yes - Parent id of each node
text string yes - Node label
droppable boolean no false If true, child nodes will be accepted and it will be able to drop other node
data any no undefined Additional data to be injected into each node.
These data are available in the render props.

Component API

Props Type Required Default Description
tree array yes The data representing the tree structure. An array of node data.
rootId number | string yes The id of the root node. It is the parent id of the shallowest node displayed in the tree view.
classes object no undefined A set of CSS class names to be applied to a specific area in the tree view.
See the Component Styling section for more information.
listComponent string no ul HTML tag for list.
listItemComponent string no li HTML tag for list items.
render function yes The render function of each node.
Please refer to the Render prop section for more details about the render functions.
dragPreviewRender function no undefined Render function for customizing the drag preview.
See the Dragging Preview section for more information on customizing the drag preview

NOTE:
The default preview is not displayed on touch devices. Therefore, if you want to support touch devices, please define a custom preview in dragPreviewRender.
onDrop function yes Callback function for when the state of the tree is changed.
The new data is passed as the argument.
See the onDrop callback section for more information.
onChangeOpen function no undefined Callback function to be called after the open/close state of a node is changed.
The function is passed an array of node IDs in the open state.
canDrop function no undefined A callback function to determine if a given node can be dropped to another node.
If nothing is returned (or if undefined is returned), the default rules are followed.
If it returns true or false, the default rules will be overridden and the dropable properties of each node will not be referenced.
This callback takes the current tree and the same option object that is passed to the onDrop callback.
See the canDrop callback section for more information.
canDrag function no undefined Callback function which should return true or false depending on if a give node should be draggable.
By default, all nodes are draggable.
sort function | boolean no true This property controls the order of the child nodes.
By default (true), they are sorted by the text property of each node.
If false, sorting is disabled. In this case, the nodes will follow the order of the array passed to the tree property.
It is also possible to customize the sorting by passing a callback function.
insertDroppableFirst boolean no true Specifies whether droppable nodes should be placed first in the list of child nodes.
placeholderRender function no undefined Render function for the drop destination placeholder. By default, placeholder is not displayed.
See the Manual sort with placeholder section for more information on using placeholder.
placeholderComponent string no li HTML tag for placeholder.
dropTargetOffset number no 0 Effective drop range of a dropable node. It is specified in pixels from the top or bottom of the node.
Used to insert a node anywhere using placeholders.

See the Manual sort with placeholder placeholder section for more information on using placeholder.
initialOpen boolean | array no false If true, all parent nodes will be initialized to the open state.
If an array of node IDs is passed instead of the boolean value, only the specified node will be initialized in the open state.
rootProps object no undefined Properties to be passed to the root element (by default, ul tag), excluding the ref and role property.

Render prop

To render each tree node, please pass a render function to the render property.

<Tree
  {...props}
  render={(node, { depth, isOpen, draggable, onToggle }) => (
    <div style={{ marginLeft: depth * 10 }}>
      {node.droppable && (
        <span onClick={onToggle}>{isOpen ? "[-]" : "[+]"}</span>
      )}
      {node.text}
    </div>
  )}
/>

The arguments passed to the render function are as follows

Name Type Description
data object Node data. (an element in the tree data array)
options.depth number The depth of the node hierarchy.
options.isOpen boolean The open and closed state of the node.
If droppable is not true, isOpen is always false.
options.draggable boolean Indicates whether this node is draggable or not.
options.hasChild boolean Flag indicating whether or not the node has children. It is true if the node has children, false otherwise.
options.isDragSource boolean Flag indicating whether this node is being dragged or not.
options.isDropTarget boolean Flag indicating whether or not this node is a drop target.
options.containerRef React.RefObject Reference to the HTML element (default: li tag) that wraps the custom node.
options.onToggle function An event handler for the open/close button of a node.

Dragging Preview

By default, the drag preview is a screenshot of a DOM node.
The dragPreviewRender property allows you to display a custom React component instead of a screenshot.

NOTE:
The default preview is not displayed on touch devices.
Therefore, if you want to support touch devices, please define a custom preview in dragPreviewRender.

<Tree
  {...props}
  dragPreviewRender={(monitorProps) => {
    const item = monitorProps.item;

    return (
      <div>
        <p>{item.text}</p>
      </div>
    );
  }}
/>

The data passed to dragPreviewRender contains the following properties

Name Type Description
item object Node data. (an element in the tree data array)
It also includes the ref property, which is a reference to the HTML element to be dragged.
clientOffset object The client offset of the pointer during the dragging operation.
It is in the format of {x: number, y: number}.
If the item is not being dragged, it is set to null.

onDrop callback

If the tree is modified by drag-and-drop, the changes can be retrieved by the onDrop callback.

const [treeData, setTreeData] = useState(initialTreeData);
const handleDrop = (
  newTree,
  { dragSourceId, dropTargetId, dragSource, dropTarget }
) => {
  // Do something

  setTreeData(newTree);
};

return <Tree {...props} tree={treeData} onDrop={handleDrop} />;

The arguments passed to the onDrop callback function are as follows

Name Type Description
newTree array This data represents the updated TreeView.
To redraw the modified TreeView, you need to set this data to the tree property.
options.dragSourceId number | string node id of the dragging source
options.dropTargetId number | string node id of the drop destination.
If the drop destination is the root node, it will be the value of the rootId property.
options.dragSource object node item of the dragging source
options.dropTarget object | undefined node item of the drop destination.
If the drop destination is the root node, it will be undefined
options.destinationIndex number | undefined If the sort property is false, the insertion destination index value of dragSource is given. Otherwise, it will be undefined.

canDrop callback

By default, it allows dropping to any dropable node (or root node) except its own descendants. This callback can override the default rules.

If it returns nothing or returns undefined, the default rules will be applied. If it returns a boolean value, it will override the default rules and the droppable property of each node will no longer be referenced.

If it returns false and the user drops the dragged node, no action will be taken and the onDrop callback will not be fired.

This callback takes the same parameters as the onDrop callback, but the first parameter specifies the current tree.

const canDrop = (
  currentTree,
  { dragSourceId, dropTargetId, dragSource, dropTarget }
) => {
  return true;

  // or

  return false;

  // or

  return;

  // or

  return undefined;
};

return <Tree {...props} tree={treeData} canDrop={canDrop} />;

NOTE:
When overriding the default rules by returning true or false, be careful of inconsistencies in the tree structure.
For example, if you allow dropping from a parent node to a child node as shown in the figure below, inconsistency will occur and the tree will collapse.

malformed tree

Manual sort with placeholder

By default, nodes are automatically sorted and cannot be sorted manually, but by combining some APIs, you can sort them manually and display placeholders as follows.

placeholder_sample

The following is an example (excerpt) of the implementation of manual sort of nodes and placeholder display.

import { CustomPlaceholder } from "./CustomPlaceholder";
import styles from "./App.module.css";

function App() {
  const [treeData, setTreeData] = useState(SampleData);
  const handleDrop = (newTree) => setTreeData(newTree);

  <Tree
    {...props}
    tree={treData}
    onDrop={handleDrop}
    classes={{
      placeholder: styles.placeholder,
    }}
    sort={false}
    insertDroppableFirst={false}
    canDrop={(tree, { dragSource, dropTargetId }) => {
      if (dragSource?.parent === dropTargetId) {
        return true;
      }
    }}
    dropTargetOffset={5}
    placeholderRender={(node, { depth }) => (
      <CustomPlaceholder node={node} depth={depth} />
    )}
  />;
}

Component Styling

You are free to define the styling of individual nodes in the tree in your Render props, but the rest of the tree can be styled by specifying the CSS class name for the classes property.

<Tree
  {...props}
  classes={{
    root: "my-root-classname",
    dragOver: "my-dragover-classname",
  }}
/>

You can use the following keys for the objects you pass to the classes property. Neither key is required.

Name Description
root CSS class name to give to the top-level container element (by default, ul tag) that wraps all nodes.
container CSS class name to give to the element wrapping the list of nodes of the same hierarchy (by default, ul tag).
listItem CSS class name to give to the element that wraps each node item (by default, li tag).
dropTarget CSS class name to give to the area that can be dropped during a node dragging operation.
draggingSource CSS class name to give to the node during the dragging operation.
placeholder CSS class name to give to the element wrapping the placeholder (by default, li tag).

Usage to open / close methods

The open/close status of a node is managed within the Tree component, but the methods for opening and closing nodes are public, so they can be controlled from outside the Tree component.

const ref = useRef(null);

const handleOpenAll = () => ref.current.openAll();
const handleCloseAll = () => ref.current.closeAll();

// open /close method can be passed a node ID or an array of node IDs
const handleOpen = (nodeId) => ref.current.open(nodeId);
const handleClose = (nodeId) => ref.current.close(nodeId);

<Tree
  ref={ref}
  {...props}
>

<button onClick={handleOpenAll}>Open All Folders</button>
<button onClick={handleCloseAll}>Close All Folders</button>
<button onClick={handleOpen}>Open specific folder(s)</button>
<button onClick={handleClose}>Close specific folder(s)</button>

License

MIT.