Скачать или смотреть Filtering Upcoming Events with Active Model Serializer in Rails

Learn how to filter out past events with `Active Model Serializer` in Rails to only show upcoming events in your JSON response.
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This video is based on the question https://stackoverflow.com/q/64672144/ asked by the user 'Ricardo Trejos' ( https://stackoverflow.com/u/6678373/ ) and on the answer https://stackoverflow.com/a/64674251/ provided by the user 'Aarthi' ( https://stackoverflow.com/u/8785865/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Filtering Upcoming Events with Active Model Serializer in Rails

In a Ruby on Rails application, it’s quite common to want to display only relevant data to users, particularly when it comes to event listings. One common requirement is to show only future events while excluding those that have already passed. This can be achieved effectively using Active Model Serializers (AMS). In this guide, we’ll go through how to set up a condition to only display upcoming events in the JSON response from a Rails API.

The Problem

Imagine you are building an event management system. You want your API to only supply upcoming events to clients. If an event’s date is in the past, it shouldn’t appear in the response. This problem can be resolved by customizing your data associations and serializing your output correctly.

Here’s the setup we'll use as an example:

Initial Serializer Logic

We start with two serializers, the EventSerializer, tailored for the event attributes, and the FeedSerializer, which is responsible for serializing collections of events.

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The Required Solution

To filter out those past events, we’ll introduce a custom association that retrieves only future events based on their date and utilize this within the FeedSerializer. Here’s how you can implement the solution step by step:

Step 1: Define a Custom Association in Your Feed Model

In your Feed model, you will create a new association called future_events. This will include a scope that filters out the events with dates that are earlier than today’s date.

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has_many :future_events: This defines a custom association named future_events.

where('date >= ?', Date.today): This condition ensures that only events that have a date on or after today are included.

Step 2: Access the Custom Association in the FeedSerializer

Next, we will modify the FeedSerializer to use the future_events instead of events:

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This change allows the FeedSerializer to serialize only the upcoming events captured by the future_events association.

Conclusion

By following the outlined steps, you can effectively filter your serialized data to only present the relevant upcoming events to your users. This not only improves the usability of your API but also optimizes the performance by reducing unnecessary data overhead. Custom associations in Rails make it simple to enforce business logic at the data retrieval level, ensuring that the client always receives only what they need.

Now you have a neat system to manage and display events with Active Model Serializer. Happy coding!