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Discover how to group properties of JavaScript objects based on other properties using a practical JSON transformation example.
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Grouping Object Properties in JavaScript: A Guide to Transforming JSON Data

In the world of programming, you often encounter the need to transform data structures into formats that are more useful or meaningful. One common scenario is grouping certain properties of objects based on other shared properties. This is particularly useful when working with JSON data from databases or APIs.

In this guide, we will walk through a practical example of how to group grades by enrollmentId using JavaScript. We'll break down the problem, show you how to implement the solution, and provide you with a clear, step-by-step approach. Let’s dive in!

Understanding the Problem

Imagine you have a JSON response from a database that looks like this:

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Your goal is to transform this data into the following structure, where you group the grades in an array for the same enrollmentId:

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The Solution

To achieve this transformation, we will use JavaScript to iterate through the given data and restructure it. Below is a complete breakdown of the solution:

Step 1: Set Up the Environment

First, ensure you have your data in a JavaScript object. In this example, we will define our gradings object as shown below:

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Step 2: Create Storage for Grouped Data

Next, we'll create two objects to help us group our data: one for the grades (gradesByEnrollmentId) and another for the unique enrollment details (enrollmentById).

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Step 3: Iterate Over the Grading Data

Now, let’s loop through the gradings array. For each grading entry, we'll check if we already have an entry for the enrollmentId and, if not, initialize it. Then, we will push the grade into the corresponding grades array.

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Step 4: Construct the Final Result

Finally, we will create a new array from the enrollmentById object, adding the corresponding grades array for each unique enrollment:

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Final Output

The final output of the above code will be:

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

Conclusion

Grouping properties of objects based on another property can be achieved effectively using JavaScript. In this post, we've walked through a practical example of transforming JSON data by grouping grades based on enrollmentId. This approach can be applied to other similar scenarios, making it a valuable technique in your programming toolkit.

Now that you have learned how to structure your data better, you can easily modify the method for different datasets. Happy coding!