I have a nested object which can be of any depth
[
{
"id": "3",
"user_id": "1479",
"folder_id": "2",
"is_folder": true,
"folder_name": "folder 3",
"unique_filename": null,
"original_filename": null,
"file_extension": null,
"content_type": null,
"file_size": null,
"description": "People",
"visible": false,
"status": 0,
"deleted_at": null,
"last_access": "2022-11-21T09:34:48.546+02:00",
"created_at": "2022-11-21T09:34:48.546+02:00",
"updated_at": "2022-11-21T09:34:48.546+02:00",
"children": [
{
"id": "36",
"user_id": "1479",
"folder_id": "3",
"is_folder": true,
"folder_name": "folder 4",
"unique_filename": null,
"original_filename": null,
"file_extension": null,
"content_type": null,
"file_size": null,
"description": "People",
"visible": false,
"status": 0,
"deleted_at": null,
"last_access": "2022-11-21T21:33:48.767+02:00",
"created_at": "2022-11-21T21:33:48.767+02:00",
"updated_at": "2022-11-21T21:33:48.767+02:00",
"children": [
{
"id": "37",
"user_id": "1479",
"folder_id": "36",
"is_folder": true,
"folder_name": "folder 37",
"unique_filename": null,
"original_filename": null,
"file_extension": null,
"content_type": null,
"file_size": null,
"description": "People",
"visible": false,
"status": 0,
"deleted_at": null,
"last_access": "2022-11-21T21:38:30.690+02:00",
"created_at": "2022-11-21T21:38:30.690+02:00",
"updated_at": "2022-11-21T21:38:30.690+02:00",
"children": []
}
]
},
{
"id": "42",
"user_id": "1479",
"folder_id": "3",
"is_folder": true,
"folder_name": "folder 41",
"unique_filename": null,
"original_filename": null,
"file_extension": null,
"content_type": null,
"file_size": null,
"description": "People",
"visible": false,
"status": 0,
"deleted_at": null,
"last_access": "2022-11-21T23:38:31.935+02:00",
"created_at": "2022-11-21T23:38:31.935+02:00",
"updated_at": "2022-11-21T23:38:31.935+02:00",
"children": []
}
]
},
{
"id": "5",
"user_id": "1479",
"folder_id": null,
"is_folder": false,
"folder_name": null,
"unique_filename": "drives/users/user_drive_1479/YTHGg4dnzn8O5a4DGHbntsrKhY2n4ycc3hZG5j7YxdIb5yEka9iToJDi9WxQPe4taSjLP53b1s01mctIy69o7m6L92.c",
"original_filename": "sample3.c",
"file_extension": "c",
"content_type": "text/x-c",
"file_size": "126",
"description": null,
"visible": false,
"status": 0,
"deleted_at": null,
"last_access": "2022-11-21T09:37:48.766+02:00",
"created_at": "2022-11-21T09:37:48.767+02:00",
"updated_at": "2022-11-21T09:37:48.767+02:00",
"children": []
},
{
"id": "7",
"user_id": "1479",
"folder_id": null,
"is_folder": false,
"folder_name": null,
"unique_filename": "drives/users/user_drive_1479/FSix4WZx0s9ey89x3foLxmaC1wCHTSw1HQi8fDxQ32bYQyKmyPJBcgeI33KOrdPfAcOChvkBnIBizj5IQbggeprCpz.cpp",
"original_filename": "sample1.cpp",
"file_extension": "cpp",
"content_type": "text/x-c",
"file_size": "94",
"description": null,
"visible": false,
"status": 0,
"deleted_at": null,
"last_access": "2022-11-21T09:37:52.324+02:00",
"created_at": "2022-11-21T09:37:52.324+02:00",
"updated_at": "2022-11-21T09:37:52.324+02:00",
"children": []
},
{
"id": "37",
"user_id": "1479",
"folder_id": "36",
"is_folder": true,
"folder_name": "folder 37",
"unique_filename": null,
"original_filename": null,
"file_extension": null,
"content_type": null,
"file_size": null,
"description": "People",
"visible": false,
"status": 0,
"deleted_at": null,
"last_access": "2022-11-21T21:38:30.690+02:00",
"created_at": "2022-11-21T21:38:30.690+02:00",
"updated_at": "2022-11-21T21:38:30.690+02:00",
"children": []
}
]
I need to get the value of all the id keys
from the array of objects above the expected outcome would be
[3,36,37,42,5,7,37]
the code I have tried is shown below
if (data.children) {
console.log(data.id)
data.children.forEach(item => {
this.getObject(item)
})
} else {
console.log(data.id)
}
the data variable being the array of objects above
I get undefined as a result.
your assistance would be much appreciated
>Solution :
Using a recursive technique can cause a stack overflow if the node treelist is too numerous. An iterative approach is safer:
type NodeWithChildren<T> = T & { children?: T[] };
function collectNodeValues <
K extends string,
T extends NodeWithChildren<Record<K, unknown>>,
>(nodeList: readonly T[], targetProperty: K): T[K][] {
const stack: T[] = [...nodeList];
const values: T[K][] = [];
while (stack.length > 0) {
const node = stack.shift()!;
values.push(node[targetProperty]);
if (!Array.isArray(node.children)) continue;
stack.unshift(...node.children);
}
return values;
}
const input = [{"id":"3","user_id":"1479","folder_id":"2","is_folder":true,"folder_name":"folder 3","unique_filename":null,"original_filename":null,"file_extension":null,"content_type":null,"file_size":null,"description":"People","visible":false,"status":0,"deleted_at":null,"last_access":"2022-11-21T09:34:48.546+02:00","created_at":"2022-11-21T09:34:48.546+02:00","updated_at":"2022-11-21T09:34:48.546+02:00","children":[{"id":"36","user_id":"1479","folder_id":"3","is_folder":true,"folder_name":"folder 4","unique_filename":null,"original_filename":null,"file_extension":null,"content_type":null,"file_size":null,"description":"People","visible":false,"status":0,"deleted_at":null,"last_access":"2022-11-21T21:33:48.767+02:00","created_at":"2022-11-21T21:33:48.767+02:00","updated_at":"2022-11-21T21:33:48.767+02:00","children":[{"id":"37","user_id":"1479","folder_id":"36","is_folder":true,"folder_name":"folder 37","unique_filename":null,"original_filename":null,"file_extension":null,"content_type":null,"file_size":null,"description":"People","visible":false,"status":0,"deleted_at":null,"last_access":"2022-11-21T21:38:30.690+02:00","created_at":"2022-11-21T21:38:30.690+02:00","updated_at":"2022-11-21T21:38:30.690+02:00","children":[]}]},{"id":"42","user_id":"1479","folder_id":"3","is_folder":true,"folder_name":"folder 41","unique_filename":null,"original_filename":null,"file_extension":null,"content_type":null,"file_size":null,"description":"People","visible":false,"status":0,"deleted_at":null,"last_access":"2022-11-21T23:38:31.935+02:00","created_at":"2022-11-21T23:38:31.935+02:00","updated_at":"2022-11-21T23:38:31.935+02:00","children":[]}]},{"id":"5","user_id":"1479","folder_id":null,"is_folder":false,"folder_name":null,"unique_filename":"drives/users/user_drive_1479/YTHGg4dnzn8O5a4DGHbntsrKhY2n4ycc3hZG5j7YxdIb5yEka9iToJDi9WxQPe4taSjLP53b1s01mctIy69o7m6L92.c","original_filename":"sample3.c","file_extension":"c","content_type":"text/x-c","file_size":"126","description":null,"visible":false,"status":0,"deleted_at":null,"last_access":"2022-11-21T09:37:48.766+02:00","created_at":"2022-11-21T09:37:48.767+02:00","updated_at":"2022-11-21T09:37:48.767+02:00","children":[]},{"id":"7","user_id":"1479","folder_id":null,"is_folder":false,"folder_name":null,"unique_filename":"drives/users/user_drive_1479/FSix4WZx0s9ey89x3foLxmaC1wCHTSw1HQi8fDxQ32bYQyKmyPJBcgeI33KOrdPfAcOChvkBnIBizj5IQbggeprCpz.cpp","original_filename":"sample1.cpp","file_extension":"cpp","content_type":"text/x-c","file_size":"94","description":null,"visible":false,"status":0,"deleted_at":null,"last_access":"2022-11-21T09:37:52.324+02:00","created_at":"2022-11-21T09:37:52.324+02:00","updated_at":"2022-11-21T09:37:52.324+02:00","children":[]},{"id":"37","user_id":"1479","folder_id":"36","is_folder":true,"folder_name":"folder 37","unique_filename":null,"original_filename":null,"file_extension":null,"content_type":null,"file_size":null,"description":"People","visible":false,"status":0,"deleted_at":null,"last_access":"2022-11-21T21:38:30.690+02:00","created_at":"2022-11-21T21:38:30.690+02:00","updated_at":"2022-11-21T21:38:30.690+02:00","children":[]}];
const ids = collectNodeValues(input, 'id');
console.log(ids); // ["3", "36", "37", "42", "5", "7", "37"]
Compiled JS from the TS Playground:
"use strict";
function collectNodeValues(nodeList, targetProperty) {
const stack = [...nodeList];
const values = [];
while (stack.length > 0) {
const node = stack.shift();
values.push(node[targetProperty]);
if (!Array.isArray(node.children))
continue;
stack.unshift(...node.children);
}
return values;
}
const input = [{ "id": "3", "user_id": "1479", "folder_id": "2", "is_folder": true, "folder_name": "folder 3", "unique_filename": null, "original_filename": null, "file_extension": null, "content_type": null, "file_size": null, "description": "People", "visible": false, "status": 0, "deleted_at": null, "last_access": "2022-11-21T09:34:48.546+02:00", "created_at": "2022-11-21T09:34:48.546+02:00", "updated_at": "2022-11-21T09:34:48.546+02:00", "children": [{ "id": "36", "user_id": "1479", "folder_id": "3", "is_folder": true, "folder_name": "folder 4", "unique_filename": null, "original_filename": null, "file_extension": null, "content_type": null, "file_size": null, "description": "People", "visible": false, "status": 0, "deleted_at": null, "last_access": "2022-11-21T21:33:48.767+02:00", "created_at": "2022-11-21T21:33:48.767+02:00", "updated_at": "2022-11-21T21:33:48.767+02:00", "children": [{ "id": "37", "user_id": "1479", "folder_id": "36", "is_folder": true, "folder_name": "folder 37", "unique_filename": null, "original_filename": null, "file_extension": null, "content_type": null, "file_size": null, "description": "People", "visible": false, "status": 0, "deleted_at": null, "last_access": "2022-11-21T21:38:30.690+02:00", "created_at": "2022-11-21T21:38:30.690+02:00", "updated_at": "2022-11-21T21:38:30.690+02:00", "children": [] }] }, { "id": "42", "user_id": "1479", "folder_id": "3", "is_folder": true, "folder_name": "folder 41", "unique_filename": null, "original_filename": null, "file_extension": null, "content_type": null, "file_size": null, "description": "People", "visible": false, "status": 0, "deleted_at": null, "last_access": "2022-11-21T23:38:31.935+02:00", "created_at": "2022-11-21T23:38:31.935+02:00", "updated_at": "2022-11-21T23:38:31.935+02:00", "children": [] }] }, { "id": "5", "user_id": "1479", "folder_id": null, "is_folder": false, "folder_name": null, "unique_filename": "drives/users/user_drive_1479/YTHGg4dnzn8O5a4DGHbntsrKhY2n4ycc3hZG5j7YxdIb5yEka9iToJDi9WxQPe4taSjLP53b1s01mctIy69o7m6L92.c", "original_filename": "sample3.c", "file_extension": "c", "content_type": "text/x-c", "file_size": "126", "description": null, "visible": false, "status": 0, "deleted_at": null, "last_access": "2022-11-21T09:37:48.766+02:00", "created_at": "2022-11-21T09:37:48.767+02:00", "updated_at": "2022-11-21T09:37:48.767+02:00", "children": [] }, { "id": "7", "user_id": "1479", "folder_id": null, "is_folder": false, "folder_name": null, "unique_filename": "drives/users/user_drive_1479/FSix4WZx0s9ey89x3foLxmaC1wCHTSw1HQi8fDxQ32bYQyKmyPJBcgeI33KOrdPfAcOChvkBnIBizj5IQbggeprCpz.cpp", "original_filename": "sample1.cpp", "file_extension": "cpp", "content_type": "text/x-c", "file_size": "94", "description": null, "visible": false, "status": 0, "deleted_at": null, "last_access": "2022-11-21T09:37:52.324+02:00", "created_at": "2022-11-21T09:37:52.324+02:00", "updated_at": "2022-11-21T09:37:52.324+02:00", "children": [] }, { "id": "37", "user_id": "1479", "folder_id": "36", "is_folder": true, "folder_name": "folder 37", "unique_filename": null, "original_filename": null, "file_extension": null, "content_type": null, "file_size": null, "description": "People", "visible": false, "status": 0, "deleted_at": null, "last_access": "2022-11-21T21:38:30.690+02:00", "created_at": "2022-11-21T21:38:30.690+02:00", "updated_at": "2022-11-21T21:38:30.690+02:00", "children": [] }];
const ids = collectNodeValues(input, 'id');
console.log(ids); // ["3", "36", "37", "42", "5", "7", "37"]