The Tree data structure is a hierarchical structure used to represent and organize data in a way that is easy to navigate and search. It consists of nodes connected by edges, with a hierarchical relationship between the nodes.

The topmost node of the tree is called the root, and the nodes below it are referred to as child nodes. Each node can have multiple child nodes, which can, in turn, have their own child nodes, forming a recursive structure.

In this blog post, I'll take you through my journey of implementing a tree structure in Node.js using MongoDB. You'll find valuable insights and practical tips to help you navigate this complex task.

Additionally, I'll demonstrate how to implement a basic user interface for editing the tree structure directly from the UI.

Why I Implemented a Tree Structure

In Hexmos Feedback, we believe in keeping teams motivated by encouraging regular, meaningful feedback, improving team commitment, and tracking participation.

To represent user titles, we have an Organizational Title management system. It displays the hierarchy, facilitates navigation, and manages title relationships. Each employee is assigned a title when signing up for the organization.

The existing organizational title management system was not up to the mark.

Organizations could not edit the titles in any way; only the default titles provided by the product were available.

We wanted a Hierarchical Organizational Title Chart in our product.

A hierarchy is an Organizational Title structure where one group or person is at the top, with others beneath them, forming a pyramid based on accountability and reporting lines.

In a hierarchy, members typically communicate with the person they report to, as well as anyone who reports directly to them. For example, in the case of a leave application.

A tree structure was the perfect solution for implementing this.

Just like a real tree with branches and leaves, it organizes titles in a hierarchical manner.

This means each title can have smaller roles beneath it. This is a natural way to represent how organizations work, making it a great fit for displaying roles and titles in our system.

We can represent the hierarchy, facilitate navigation, and manage title relationships. This enhances team commitment and collaboration.

What were our use cases in UI and backend implementation?

Displaying Titles Similar to a Tree Structure

Tree structures are ideal for representing hierarchical data like organizational titles and folder structures.

They allow you to visually organize and display information in a clear and intuitive manner. This is particularly useful when dealing with complex hierarchies with many levels and subcategories.

Displaying the Hierarchy

One of the early challenges we encountered was finding an effective way to visualize the hierarchical structure of our titles in a clear, organized, and intuitive manner.

Our initial approach involved hard-coding the hierarchy, which provided a functional solution but lacked flexibility.

We aimed to create a more dynamic and user-friendly experience by allowing users to see how titles relate to each other, similar to a tree structure.

Our objective was to enable each title (or node) to be connected to a parent title and have multiple child titles beneath it.

The user interface needed to accurately reflect this tree-like structure, making it easy for users to understand and navigate through the various levels of titles.

Customization and User Interaction

Customization was a crucial aspect of our project.

We wanted to empower users to not only view the hierarchical structure but also actively interact with it. This involved providing functionalities such as:

• Creating New Titles: Users should be able to add new titles at any level of the hierarchy.
• Editing Titles: Titles may evolve over time, so we needed to enable easy editing within the user interface.
• Reassigning Titles: In the event of organizational changes, users should be able to move titles from one parent to another without disrupting the overall hierarchy.

This level of customization enhances flexibility and ensures that the hierarchy remains dynamic and adaptable to various organizational requirements.

Visualizing Organizational Titles in a Better Way

By using a tree structure, you can create a more visually appealing and interactive representation of your organizational titles. This can make it easier for users to understand the relationships between different titles and navigate the hierarchy.

Implementation Strategy

We wanted to keep things simple at first, so we could easily add more features later. We thought about building everything ourselves, but after talking to other developers and doing some research, we decided to see what was already available. It made more sense to use existing tools than to start from scratch – it would have taken way too much time.

For editing titles, we found a great tool called JSON Editor (link: JSON Editor). It lets users easily view and change the data structure. On the backend, we took an open-source project that stores data in a tree-like format and modified it to fit our specific needs. This way, we didn't have to build everything from scratch, but we still got a solution that worked perfectly for us.

Implementing Basic CRUD Operations

On the backend, the core functionality revolved around basic CRUD (Create, Read, Update, Delete) operations for our title hierarchy. Each node (representing a title) needed to be efficiently created, stored, modified, and deleted.

• Create: Adding a new node in the hierarchy required assigning it to a parent node, whether at the top (CEO-level, for example) or deeper in the structure.
• Read: This involved fetching the entire hierarchy from MongoDB, which stored each node and its relation to other nodes.
• Update: Updating nodes required the ability to edit the title itself and change its position within the hierarchy (i.e., assigning it a new parent).
• Delete: Deleting a node meant removing it from the hierarchy, while also considering how to handle its child nodes — whether they should be reassigned to a new parent or deleted as well.

MongoDB proved to be an excellent choice for this, as it allows for flexible storage of hierarchical data using tree structures.

Its JSON-like documents made it straightforward to store each node along with its relationships.

Storing the Title Hierarchy in Tree Structure

The final step in the backend implementation was to store the hierarchical structure in a way that MongoDB could efficiently handle. We employed a parent-child model, where each node in the tree stored a reference to its parent node. This allowed us to easily traverse the hierarchy, fetch child nodes as needed, and move nodes to different parts of the tree.

We also utilized recursive queries to retrieve the entire hierarchy in one request, enabling the front end to render the tree without performance issues. Each node in MongoDB stored fields such as:

• title: The name of the title (e.g., Manager, Director)
• parentId: The ID of the parent node (for linking the hierarchy)
• children: An array of child nodes (to facilitate traversal)

With these core components in place, we had a fully functional backend that supported the dynamic management of title hierarchies.

Node.js Backend Implementation

This file structure promotes maintainability, scalability, and clarity in your Node.js backend project.

It effectively separates concerns, making code easier to understand, modify, and collaborate on.

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