Скачать или смотреть Fixing Kaminari Pagination Issues in Rails 7: How to Adapt Your User Data List

Discover how to handle pagination issues in Rails 7 when modifying user data with Kaminari. Learn effective solutions and code snippets for seamless pagination integration.
---
This video is based on the question https://stackoverflow.com/q/75025174/ asked by the user 'A. Vreeswijk' ( https://stackoverflow.com/u/10673107/ ) and on the answer https://stackoverflow.com/a/75025315/ provided by the user 'Ben Trewern' ( https://stackoverflow.com/u/887947/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Rails 7: Kaminari data list modified and not recognized for pagination

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Resolving Kaminari Pagination Issues in Rails 7

Pagination is an essential feature for any web application that deals with large sets of data. It allows users to navigate through records without overwhelming them with information. However, sometimes, when we modify our data sets, we encounter issues—like the one faced by a Rails 7 developer implementing Kaminari. Let’s delve into the problem and then explore how to fix it.

The Problem

In your Rails 7 application, you have successfully implemented Kaminari for paginating users in your controller. Here’s your initial code that sets up the pagination based on user creation dates and applies filters for gender, job, and car:

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

However, after adding a Scanner::Origin.calculate method that modifies some parts of the user data, you encountered the following error message:

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

This happens because when you modify the users list with the new method, it loses the Kaminari pagination capabilities since it’s no longer a paginated relationship. Even when you try to call page again on the modified list, you encounter another error:

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

Clearly, there is a disconnect after the data modification process. Let's explore the solution!

The Solution

Step 1: Maintaining Paginated Data Structure

The primary objective is to ensure that after modifying the user data, you still have access to the Kaminari methods for pagination. To achieve this, you should avoid breaking the active relation chain. One way to do this is to apply any transformations to the user data before calling the pagination methods.

Updated Controller Code

Here’s how you might adjust your index action to keep the pagination functionality intact while applying data modifications:

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

What This Code Does

Ordering Users: The list of users is ordered by creation date in descending order.

Filtering Users: Users are filtered based on provided parameters (gender, job, car).

Pagination: The page and per methods from Kaminari are applied before calling the Scanner::Origin.calculate method, ensuring that the user list remains a paginated collection.

Data Modification: Finally, your data modification happens on the correctly paginated collection.

Benefits of This Approach

Keeps Pagination Intact: By applying page before modifications, you can still access pagination properties like total_pages.

Flexible Filters: Your code remains clean and retains the ability to filter results dynamically based on user input.

Error-Free Operation: You minimize the chances of encountering undefined method errors related to pagination.

Conclusion

In conclusion, modifying a list of users in Rails 7 while using Kaminari for pagination requires careful handling to ensure the original paginated data structure is maintained. By appropriately ordering, filtering, and paginating before data modifications, you can significantly enhance user experience while avoiding frustrating errors. Happy coding!