Solving Mongoose Pagination Issues: Add Sorting to Avoid Duplicate Data

Learn how to fix pagination issues in Mongoose when sorting with identical values. Ensure accurate movie listings without duplicates.
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Fixing Mongoose Pagination with Sorting Issues

When working with Mongoose for your database management, you may encounter a frustrating issue—pagination that doesn't seem to work correctly when sorting. Specifically, the issue arises when sorting documents that contain identical values. This article delves into this problem and provides a clear solution for ensuring your pagination functions flawlessly while sorting your data.

The Problem: Pagination Fails with Sorting

Many developers might notice that their pagination works perfectly until they introduce sorting. A common scenario arises in listing movies, particularly when sorting by release_date. You might use a function like the following:

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

Issues with Sorting

When you add sorting, you might start to notice some peculiarities:

You get repeated records from previous pages.

The lack of unique identifiers in the sorted results leads to inconsistencies in pagination.

Why Does This Happen?

The root cause of this problem lies in how Mongoose handles sorting. If multiple documents have the same release_date, Mongoose can't distinguish between them during sorting, which results in unexpected pagination behavior. Essentially, your movies are getting mixed up, and the records returned on subsequent pages include some from the previous page.

The Solution: Enhance Your Sorting Criteria

To resolve this issue, you must refine your sorting criteria. The solution is simple but effective: introduce the _id field as a secondary sort parameter. This gives Mongoose an additional unique identifier to use when sorting documents with identical release_date values.

Implementing the Solution

Modify the sort part of your code to include _id like so:

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

Updated Function

Here’s how your complete function would look with the improved sorting criteria:

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

Conclusion

By adding _id to the sorting criteria, you instruct Mongoose to sort not just by release_date, but also by the unique identifiers of the documents, ensuring that each record is distinct even when their release_date values are the same. This adjustment will keep your pagination working correctly and improve the integrity of your movie listings.

If you encounter similar issues in your Mongoose applications, remember this simple adjustment—it can save you a lot of headaches!