@mui/x-tree-view/esm/internals/plugins/lazyLoading/selectors.js

The community edition of the MUI X Tree View components.

import { createSelector } from '@mui/x-internals/store';
import { TREE_VIEW_ROOT_PARENT_ID } from "../items/index.js";
export const lazyLoadingSelectors = {
  /**
   * Checks if the lazy loaded state is empty.
   */
  isEmpty: createSelector(state => {
    if (state.lazyLoadedItems == null) {
      return true;
    }
    return Object.keys(state.lazyLoadedItems.loading).length === 0 && Object.keys(state.lazyLoadedItems.errors).length === 0;
  }),
  /**
   * Checks whether an item is loading.
   */
  isItemLoading: createSelector((state, itemId) => state.lazyLoadedItems?.loading[itemId ?? TREE_VIEW_ROOT_PARENT_ID] ?? false),
  /**
   * Checks whether an item has errors.
   */
  itemHasError: createSelector((state, itemId) => !!state.lazyLoadedItems?.errors[itemId ?? TREE_VIEW_ROOT_PARENT_ID]),
  /**
   * Get an item error.
   */
  itemError: createSelector((state, itemId) => state.lazyLoadedItems?.errors[itemId ?? TREE_VIEW_ROOT_PARENT_ID])
};