useGetTree

This Enterprise Edition hook is exposed by the ra-tree module, a package dedicated to handling tree structures. It’s ideal for fetching a tree structure from the API, e.g. a list of categories.

It calls dataProvider.getTree() (one of the new dataProvider methods supported by ra-tree) when the component mounts, and returns the tree nodes in a flat array.

Usage

Use it like other dataProvider hooks:

import { useGetTree, getRCTree, Tree } from '@react-admin/ra-tree';

const Categories = () => {
    const { data, isLoading, error } = useGetTree('categories');
    if (isLoading) { return <Loading />; }
    if (error) { return <p>ERROR</p>; }

    return <Tree treeData={getRCTree(data)} />;
};

data will contain an array of TreeRecord objects. A TreeRecord contains at least an id field and a children field (an array of child ids). For instance:

[
  { id: 1, title: 'foo1', children: [3, 4] },
  { id: 2, title: 'foo2', children: [] },
  { id: 3, title: 'foo3', children: [5] },
  { id: 4, title: 'foo4', children: [] },
  { id: 5, title: 'foo5', children: [] },
]

The <Tree> component is a wrapper for rc-tree’s <Tree>, with Material Design style. It expects a treeData prop containing a tree of nodes with a special format (hence the getRCTree converter).

Other Tree Hooks

useGetTree is one of many hooks added by ra-tree. This package recommends adding several methods to the dataProvider, and has one hook for each method.

Read methods

  • getTree(resource)
  • getRootNodes(resource)
  • getParentNode(resource, { childId })
  • getChildNodes(resource, { parentId })

These methods return Promises for TreeRecord objects.

Write methods

  • moveAsNthChildOf(resource, { source, destination, position, meta }): source and destination are TreeRecord objects, and position a zero-based integer
  • moveAsNthSiblingOf(resource, { source, destination, position, meta })
  • addRootNode(resource, { data, meta })
  • addChildNode(resource, { parentId, data, position, meta })
  • deleteBranch(resource, { id, data, meta }): id is the identifier of the node to remove, and data its content

Check the ra-tree documentation for more details.