Export

FlexTreeManager and FlexTree support exporting the tree to Json and List formats.

The following uses the tree below to illustrate how to export a tree.

• Root
  • A
  • B
  • C

toJson

FlexTreeManager, FlexTree, and FlexTreeNode all support the toJson method, which exports the tree to Json format.

toJson(
    options?: FlexTreeExportJsonOptions<Fields, KeyFields>
): FlexTreeExportJsonFormat<Fields, KeyFields>

interface FlexTreeExportJsonOptions<
    Fields extends Record<string, any> = object,
    KeyFields extends CustomTreeKeyFields = DefaultTreeKeyFields,
> {
    childrenField?: string
    level?: number // Limit the level to export
    fields?: (keyof IFlexTreeNode<Fields, KeyFields>)[]
    includeKeyFields?: boolean
    countField?: string // Attach a descendant-count field
}

• Parameters

Parameter	Type	Default	Description
options	FlexTreeExportJsonOptions	None	Export options
options.childrenField	string	'children'	Child field name
options.level	number	None	Limit the level to export
options.fields	(keyof IFlexTreeNode<Fields, KeyFields>)[]	None	Fields to export
options.includeKeyFields	boolean	false	Whether to export key fields
options.countField	string	None	Descendant-count field name

• Return

Returns a JSON object whose child field name defaults to children; it can be customized via the options.childrenField parameter.

type FlexTreeExportJsonFormat<
  Fields extends Record<string, any> = object,
  KeyFields extends CustomTreeKeyFields = DefaultTreeKeyFields,
  TreeNode extends IFlexTreeNode<Fields, KeyFields> = IFlexTreeNode<Fields, KeyFields>,
  NodeId = NonUndefined<KeyFields["id"]>[1],
> = TreeNode & {
  children?: FlexTreeExportJsonFormat<Fields, KeyFields, TreeNode, NodeId>[];
};

• Example

import type { FlexTreeOptions, IFlexTreeNode } from "flextree";
import { FlexTreeManager, FlexTree, FlexTreeVerifyError } from "flextree";

import SqliteAdapter from "flextree-sqlite-adapter";
const sqliteDriver = new SqliteAdapter();
await sqliteDriver.open();

const tree = new FlexTree("tree", {
  adapter: sqliteDriver,
});
await tree.load();

tree.toJson();

The output is as follows:

{
  "id": 1,
  "name": "root",
  "children": [
    {
      "id": 2,
      "name": "A",
      "children": [
        { "id": 3, "name": "A1" },
        { "id": 4, "name": "A2" },
        { "id": 5, "name": "A3" }
      ]
    },
    {
      "id": 6,
      "name": "B",
      "children": [
        { "id": 7, "name": "B1" },
        { "id": 8, "name": "B2" },
        { "id": 9, "name": "B3" }
      ]
    },
    {
      "id": 10,
      "name": "C",
      "children": [
        { "id": 11, "name": "C1" },
        { "id": 12, "name": "C2" },
        { "id": 13, "name": "C3" }
      ]
    }
  ]
}

• Notes

  • The toJson method exports the tree to Json format; you can limit the exported level via the options.level parameter.
  • The toJson method can be called on FlexTree and FlexTreeNode.
  • You can specify the exported fields via the options.fields parameter.
  • By default the leftValue and rightValue fields are not exported; use options.includeKeyFields to specify whether to export key fields.
  • You can specify the child field name via the options.childrenField parameter.

countField Descendant Count

When options.countField is specified, each node gets an extra field holding its descendant count (0 for leaves):

await manager.toJson({ countField: "count" })
// { "id": 1, "name": "root", "count": 12, "children": [
//    { "id": 2, "name": "A", "count": 3, "children": [...] },
//    ...
// ] }

• The count is computed as (rightValue - leftValue - 1) / 2 and is always the full descendant count — unaffected by level truncation (with level: 2, the root's count still includes deeper descendants)
• countField has the same standing as id: it is attached even when fields filtering is specified, independent of includeKeyFields
• Conflicting with an existing node field throws a FlexTreeError
• With the recycle bin enabled the count uses the visible scope: by default it excludes recycled nodes (consistent with the exported content); with includeRecyclebin: true it is the full physical count

toList

FlexTreeManager, FlexTree, and FlexTreeNode all support the toList method, which exports the tree to a list node array with a pid field.

toList(
    options?: FlexTreeExportListOptions<Fields, KeyFields>
): FlexTreeExportListFormat<Fields, KeyFields>
interface FlexTreeExportListOptions<
    Fields extends Record<string, any> = object,
    KeyFields extends CustomTreeKeyFields = DefaultTreeKeyFields,
> {
    pidField?: string
    level?: number // Limit the level to export
    fields?: (keyof IFlexTreeNode<Fields, KeyFields>)[]
    includeKeyFields?: boolean
    countField?: string // Attach a descendant-count field
}

• Parameters

Parameter	Type	Default	Description
options	FlexTreeExportListOptions	None	Export options
options.pidField	string	'pid'	Parent field name
options.level	number	None	Limit the level to export
options.fields	(keyof IFlexTreeNode<Fields, KeyFields>)[]	None	Fields to export
options.includeKeyFields	boolean	false	Whether to export key fields
options.countField	string	None	Descendant-count field name

• Return

Returns a list node array whose parent field name defaults to pid; it can be customized via the options.pidField parameter.

export type FlexTreeExportListFormat<
  Fields extends Record<string, any> = object,
  KeyFields extends CustomTreeKeyFields = DefaultTreeKeyFields,
  TreeNode extends IFlexTreeNode<Fields, KeyFields> = IFlexTreeNode<Fields, KeyFields>,
  NodeId = NonUndefined<KeyFields["id"]>[1],
  OPTIONS extends FlexTreeExportListOptions<Fields, KeyFields> = FlexTreeExportListOptions<
    Fields,
    KeyFields
  >,
> = ((OPTIONS["fields"] extends string[]
  ? Extract<TreeNode, OPTIONS["fields"][number]>
  : TreeNode) & { [P in OPTIONS["pidField"] & string]: NodeId })[];

• Example

import type { FlexTreeOptions, IFlexTreeNode } from "flextree";
import { FlexTreeManager, FlexTree, FlexTreeVerifyError } from "flextree";
import SqliteAdapter from "flextree-sqlite-adapter";
const sqliteDriver = new SqliteAdapter();
await sqliteDriver.open();

const tree = new FlexTree("tree", {
  adapter: sqliteDriver,
});
await tree.load();

tree.toList();

The output is as follows:

[
  { "id": 1, "name": "root", "pid": 0 },
  { "id": 2, "name": "A", "pid": 1 },
  { "id": 3, "name": "A1", "pid": 2 },
  { "id": 4, "name": "A2", "pid": 2 },
  { "id": 5, "name": "A3", "pid": 2 },
  { "id": 6, "name": "B", "pid": 1 },
  { "id": 7, "name": "B1", "pid": 6 },
  { "id": 8, "name": "B2", "pid": 6 },
  { "id": 9, "name": "B3", "pid": 6 },
  { "id": 10, "name": "C", "pid": 1 },
  { "id": 11, "name": "C1", "pid": 10 },
  { "id": 12, "name": "C2", "pid": 10 },
  { "id": 13, "name": "C3", "pid": 10 }
]

Note

Both toList and toJson support a level parameter to limit the exported level. They can be called on FlexTree and FlexTreeNode. The semantics of countField are described in countField Descendant Count above.

getTree

FlexTreeManager provides the getTree method, which builds an in-memory FlexTree object based on the current manager, so that you can use the rich API provided by FlexTree (such as getByPath, find, toJson, toList, etc.).

getTree(options?: FlexTreeOptions): FlexTree<Fields, KeyFields>

• Example

const tree = manager.getTree()
await tree.load()           // FlexTree must be loaded manually before it can be accessed
tree.getByPath('/A/A-1')

Note

FlexTreeManager also provides two async convenience methods, toJson and toList, which automatically build and load the tree via getTree before exporting:

await manager.toJson()
await manager.toList()