您需要注册一个Doctrine自定义类型，以便将JSON数据库字段序列化/反序列化为集合对象。
示例：

<?php
namespace My\Project\Types;

use Doctrine\DBAL\Types\Type;
use Doctrine\DBAL\Platforms\AbstractPlatform;

/**
 * My custom datatype.
 */
class MyType extends Type
{
    const MYTYPE = 'mytype'; // modify to match your type name

    public function getSQLDeclaration(array $fieldDeclaration, AbstractPlatform $platform)
    {
        // return the SQL used to create your column type. To create a portable column type, use the $platform.
    }

    public function convertToPHPValue($value, AbstractPlatform $platform)
    {
        // This is executed when the value is read from the database. Make your conversions here, optionally using the $platform.
    }

    public function convertToDatabaseValue($value, AbstractPlatform $platform)
    {
        // This is executed when the value is written to the database. Make your conversions here, optionally using the $platform.
    }

    public function getName()
    {
        return self::MYTYPE; // modify to match your constant name
    }
}

然后在Symfony配置中为DoctrineBundle注册自定义类型。

doctrine:
  dbal:
    types:
      my_type:  My\Project\Types\MyType