PostgreSQL & Doctrine Unique Index With Null Values

An elegant solution to a real life problem.

Photo by David Pupăză on Unsplash

I’m a fan of PostgreSQL, especially when working with Symfony and Doctrine. However, one recurring issue compared to MySQL is how unique constraints treat NULL values. In PostgreSQL, NULL is considered a unique value, so multiple rows with NULL in a column that has a unique constraint are allowed. This behavior can be problematic when trying to enforce real-world uniqueness, where you would expect only one row with either a specific value or NULL.

Doctrine doesn’t provide native support for partial indexes or filtered unique constraints, which are PostgreSQL-specific features that could help address this. As a result, many developers resort to raw SQL in migrations to manually add these constraints, which breaks the workflow purely within the Doctrine abstraction.

To tackle this, I’ve built my own solution that integrates better with Doctrine. It allows defining conditional unique constraints in a Doctrine-friendly way.

This approach keeps things cleaner and more maintainable as it automates the database migration generation.

While it’s not perfect, it bridges the gap and makes PostgreSQL’s powerful indexing features more accessible when using Doctrine. The solution:

• allows marking the…