Solving the SQLSTATE[42S22] Error in Laravel: Custom Model Ordering with Nested Relations

Learn how to effectively order related models in Laravel by using joins for custom columns in nested relations and avoid SQL errors.
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Troubleshooting Custom Ordering with Laravel Nested Relations

If you're using Laravel and dealing with complex model relationships, you might run into issues when trying to order related models by columns from nested relations. This is especially common when using aggregate functions that create virtual columns but don’t exist in the actual database tables. Below, we’ll break down a common problem and provide an effective solution.

The Problem

Imagine you have a model structure with the following relationships:

Product model with a hasMany() relation to the ProductDefaultSpec model.

ProductDefaultSpec model that includes a belongsTo() relation with the ProductSpecType model, containing an integer field called order_value.

You might be trying to retrieve ProductDefaultSpec entries ordered by the order_value from ProductSpecType and you set it up like this:

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

While this approach works for ordering in the query, you might encounter an error such as:

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

This error occurs because product_spec_type_order_value is a virtual column created by withAggregate() but doesn't actually exist in your database table.

The Solution: Using Joins for Ordering

The good news is there is a straightforward solution. Instead of relying on virtual columns, you can modify your relation to explicitly join the related table, allowing you to order by that table's column directly. Here’s how:

Step-by-Step Guide

Modify Your Relationship: Adjust the productDefaultSpecs method to include a join statement.

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

Breakdown of the Solution:

Join Clause: This line joins the product_spec_types table based on the foreign key in product_default_specs.

Selecting Columns: The select() method specifies that you want to only retrieve columns from the product_default_specs table to avoid any column conflicts that may arise due to the join.

Conclusion

By employing a join table strategy, you can effectively sort related models by any column in a nested relation without running into SQL errors. Now you can continue utilizing your Laravel models with the confidence that your queries will return the desired results without complications.

This new approach should also eliminate the errors you encountered when attempting to delete related models. Happy coding!