How to Find the Parent Name from Child Using Lodash and Print the Path

Описание: Discover how to effectively traverse a tree-like data structure using Lodash in JavaScript to find the parent names of any given child element and print their path back to the root node.
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This video is based on the question https://stackoverflow.com/q/64606055/ asked by the user 'Nidhin Kumar' ( https://stackoverflow.com/u/10982622/ ) and on the answer https://stackoverflow.com/a/64606252/ provided by the user 'Nina Scholz' ( https://stackoverflow.com/u/1447675/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Finding Parent Names of a Child Element in JavaScript

When dealing with hierarchical data structures like trees, it can often be challenging to traverse back up to the root from a given child element. A common requirement in such scenarios is to find the parent names of a specific child and construct a path that reveals the lineage. In this guide, we'll see how to achieve this using Lodash in JavaScript.

The Problem

Let's start by looking at an example structure. We have a collection of classes represented as objects with id, class_name, and parent_id fields:

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In this structure, we know that the child class SubFolder1 has an id of 4 and a parent_id of 2. Our goal is to traverse back to the root node and find the full path, which should look something like this:

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The Solution

To solve this problem, we can create a function that gathers all parent nodes until we reach the root node (where parent_id is 0). Here’s how we can implement this using Lodash.

1. Setup the Function

We'll use the following JavaScript function, which employs a recursive approach to navigate through the structure:

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2. Breakdown of the Code

Reducing the Array: We first reduce the array into an object nodes, where each id points to its respective object. This allows for fast lookups.

Recursive Function getP: The helper function getP checks if the current id exists in our nodes object. If it does, it calls itself recursively for the parent_id while concatenating the class_name of the current node.

Joining the Result: Finally, once we reach the root (where parent_id is 0), we join the results to create a complete path string.

3. Using the Function

Now, to get the path for SubFolder1, we simply call our function:

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This will output:

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Conclusion

Finding parent names of a child and printing the path back to the root node can be easily accomplished in JavaScript using a recursive approach. By leveraging Lodash's powerful array manipulation capabilities, we streamlined our solution.

Now, you can use this method to traverse any similar hierarchical structure and extract paths dynamically based on your requirements. Happy coding!