Case-sensitive query using BINARY in Doctrine: DQL Function Extension Guide

Implement the MySQL BINARY keyword for case-sensitive queries in Doctrine ORM and Query Builder. Since Doctrine does not directly support all database native functions by default, we will solve this problem by installing the beberlei/DoctrineExtensions library and registering custom DQL functions, so as to seamlessly use BINARY for precise matching in DQL statements, and discuss its applications and precautions.

Understand the compatibility of Doctrine with native SQL functions

When using Doctrine ORM for database operations, developers usually tend to use the Query Builder or DQL (Doctrine Query Language) they provide to build queries to keep the ORM's abstraction layer independent of database. However, certain database functions, such as MySQL's BINARY keyword, are used to force case-sensitive string comparisons, do not fall into the standard category of DQL. Writing r.name = BINARY :name directly in the where clause of Query Builder will cause Doctrine to fail to parse this BINARY function, thus throwing an error.

This is because DQL is designed as a database abstraction language that supports only a common set of SQL functions. For non-standard functions of a specific database (such as MySQL), Doctrine ORM needs to be extended through the "custom DQL function" mechanism.

Solution: Introduce the DoctrineExtensions library

In order to seamlessly use MySQL-specific functions like BINARY in Doctrine, the most recommended and convenient way is to use the beberlei/DoctrineExtensions library. This library provides a large number of commonly used database functions as DQL extensions, greatly enhancing Doctrine's flexibility.

1. Install DoctrineExtensions

First, add the beberlei/DoctrineExtensions library to your project via Composer:

 composer requires beberlei/doctrineextensions

2. Configure Doctrine to register BINARY functions

After the installation is complete, the BINARY function needs to be registered in the Doctrine configuration to make it a recognizable DQL function. This is usually done in the config/packages/doctrine.yaml file of the Symfony project, or is configured directly through the Doctrine ORM in other PHP projects.

Symfony configuration example:

 # config/packages/doctrine.yaml

doctrine:
    orm:
        # ... Other ORM configuration dql:
            string_functions:
                binary: DoctrineExtensions\Query\Mysql\Binary

This configuration tells Doctrine that when the BINARY function appears in DQL, the DoctrineExtensions\Query\Mysql\Binary class should be used to handle it. string_functions means this is a function that handles strings.

3. Use BINARY in DQL or Query Builder

After completing the above configuration, you can directly use the BINARY keyword in DQL query or Query Builder for case-sensitive comparisons.

Example using Query Builder:

 <?php use Doctrine\ORM\EntityManagerInterface;
use App\Entity\Records; // Assume that your entity class is Records

class RecordRepository
{
    private $entityManager;

    public function __construct(EntityManagerInterface $entityManager)
    {
        $this->entityManager = $entityManager;
    }

    /**
     *Case sensitive query based on name*
     * @param string $name Name to query * @return array
     */
    public function findRecordsCaseSensitive(string $name): array
    {
        $repo = $this->entityManager->getRepository(Records::class);

        return $repo->createQueryBuilder('r')
            ->select('r.id', 'r.name') // More fields can be selected ->where('BINARY(r.name) = :name') // Note: In DQL, BINARY is usually used as a function, such as BINARY(column)
            ->setParameter('name', $name)
            ->getQuery()
            ->getResult();
    }
}

Important tip: In DQL, BINARY is usually used as a function, i.e. BINARY(expression), rather than being placed directly before the column name like native SQL. Although WHERE column = BINARY 'text' is valid in some MySQL native queries, it is considered as a function BINARY(column) more in line with the syntax habits of DQL functions. The Binary class in DoctrineExtensions is also registered and parsed in function form.

Further Explore: Other Features Offered by DoctrineExtensions

beberlei/DoctrineExtensions not only provides BINARY functions, but also includes a large number of other practical MySQL (as well as PostgreSQL, SQLite, etc.) function extensions, covering multiple aspects such as date, time, numerical and string processing. For example:

• Date-time functions: DATE_FORMAT, DATEDIFF, FROM_UNIXTIME, etc.
• Numerical functions: ACOS, CEIL, FLOOR, ROUND, etc.
• String functions: CONCAT_WS, GROUP_CONCAT, MD5, REPLACE, REGEXP, etc.

By consulting DoctrineExtensions' official documentation or the config/mysql.yml file in its GitHub repository, you can discover more functions that can be registered and used.

Notes and best practices

1. Database Compatibility: The BINARY keyword is unique to MySQL. If your project needs to support multiple databases (such as MySQL and PostgreSQL), using BINARY may reduce the portability of DQL. In this case, you may want to consider other case-sensitive methods across databases, such as adjusting the character set and collation of database columns, or case-sensitive at the application level (but this is usually less efficient).
2. Performance Impact: Using functions such as BINARY(r.name) in the WHERE clause may prevent the database from using indexes created for the r.name column, resulting in full table scans and affecting query performance. If case-sensitive queries are core requirements and the data volume is large, the following alternatives are recommended:
   • Modify the sorting of columns: Set the sorting of the name column to case sensitive (for example, utf8mb4_bin or utf8mb4_0900_as_cs). In this way, the default = comparison will be case sensitive and the index will work normally without using the BINARY function.
   • Add case-sensitive indexes: If you do not change the default collation of the column, consider creating a functional index for BINARY(name) (if your database version supports it).
3. DQL function naming: The function name (for example, binary) registered in doctrine.yaml will be the name you use in DQL. Please make sure that this name is clear and does not conflict with DQL built-in functions.

Summarize

Through the beberlei/DoctrineExtensions library, the DQL function of Doctrine ORM has been significantly enhanced, allowing developers to take advantage of powerful functions unique to the database while maintaining the advantages of ORM abstraction. For scenarios where case sensitive queries are required in Doctrine Query Builder, registering BINARY DQL functions provides a concise and effective solution. However, when implementing such specific database functions, it is important to consider its potential impact on database compatibility and query performance and select the most appropriate strategy based on specific needs.

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