How to Successfully Merge Nested Arrays with JavaScript

This guide provides a clear, step-by-step guide on merging two nested arrays of JSON data by adding a new property using JavaScript. Learn how to organize and structure your data correctly for optimal performance.
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How to Successfully Merge Nested Arrays with JavaScript

Merging nested arrays of JSON data can be a challenging task, especially when working with data from APIs. In this post, we'll tackle a common problem: how to efficiently merge two datasets by adding a new property based on a matching key. We will use the example of two datasets coming from a Drupal REST-API, where we want to combine DATA 1 and DATA 2 using the property tid.

Understanding the Problem

We're given two arrays of JSON objects:

DATA 1

This represents types of menus and contains:

name: The name of the menu type (e.g., "Appetiser").

tid: A unique identifier for each menu type.

desc: A description of the menu type.

[[See Video to Reveal this Text or Code Snippet]]

DATA 2

This contains menu items and has the following properties:

title: The name of the menu item (e.g., "Garlic Mushroom").

menu_item: A description of what the item is.

rate: The price of the menu item.

menu_type: The menu to which the item belongs.

tid: The same unique identifier used in DATA 1.

[[See Video to Reveal this Text or Code Snippet]]

Expected Output

The goal is to produce a single array where each item from DATA 1 includes a new property called menu, which is an array of corresponding items from DATA 2.

The Solution

Step-by-Step Approach

Copy DATA 1 to ensure we do not alter the original data.

Iterate over the copied data to add a new property menu.

Loop through DATA 2 to find items that match the tid.

Push matching items into the menu property for relevant entries.

Implementation

Here’s how you can achieve this using JavaScript:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Code

Mapping and Initializing: We create a copy of data1 and initialize menu as an empty array within each object.

Nested Loops: For each object in the copied array, we loop through data2 to find matches based on tid.

Destructuring: We use destructuring to extract properties from the matching objects and push new objects containing only necessary properties into the menu array.

Conclusion

By following these simple steps, you can effectively merge two datasets obtained from APIs or databases. This process is particularly useful when structuring complex data for applications that require high levels of organization and precision. Now, go ahead and try merging your own datasets with ease!

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