Скачать или смотреть Filtering Eloquent Relationships in Laravel: Get Records Where Column Is Not Null

Discover how to filter Eloquent relationship records in Laravel to retrieve items and their parts where specific columns are not null.
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This video is based on the question https://stackoverflow.com/q/70870769/ asked by the user 'nikname' ( https://stackoverflow.com/u/13651416/ ) and on the answer https://stackoverflow.com/a/70871217/ provided by the user 'Clément Baconnier' ( https://stackoverflow.com/u/8068675/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Filtering Eloquent Relationship Records in Laravel

In the world of Laravel development, working efficiently with Eloquent models is crucial. One common requirement arises when you want to fetch related records based on certain conditions—specifically, when a column contains non-null values. In this guide, we'll look at a typical scenario where you might need to filter relationship records and then walk through an effective solution.

Understanding the Problem

Imagine you have two tables: Items and Parts. The relationship is such that each item can have multiple parts. Here's a brief overview of the structure:

Items Table

idname1item12item2Parts Table

iditem_idname11part121part232null42part3In the Item model, you define a relationship to fetch parts associated with that item:

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

Conversely, in the Part model, you set up the link back to the item:

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

Your Attempt

You may have tried the following code, which retrieves items and their parts, where at least one part has a non-null name:

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

This query successfully returns item1, but it doesn’t include item2 because one of its parts has a null value, even though item2 has another part with a valid name. Hence, we are missing out on item2 altogether.

The Solution

To tackle this issue, you'll need to adjust your query to ensure you're fetching both items and their valid parts. The key is to utilize a subquery with the with() method. Here’s how you can modify your approach:

Step-by-Step Query Update

Use Eager Loading with Conditions: Load the parts but filter them at the same time.

Refine Your Main Query: Ensure you still get items that have at least one part with a non-null name.

Here’s how you accomplish this in Laravel:

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

Breaking It Down

with(['parts' => function($query) { ... }]): This part tells Eloquent to eager load the parts relationship but filters them to include only those parts with a non-null name.

whereHas('parts', function($query) { ... }): This ensures that you only retrieve items that indeed have parts with a non-null name.

Conclusion

With this solution, you'll retrieve all items, including item2, while only pulling in the parts that meet your criteria. It’s essential to construct your queries thoughtfully to ensure you're not missing relevant data due to conditions in your queries.

By modifying your Eloquent queries as shown, you can handle complex relationships effectively while retrieving the exact data you need. Happy coding with Laravel!