Add Index on a query using JSON_GET or other methods

[alexander-schranz]

More a question. I want to add a index on a specific JSON query I know its possible via PostgreSQL the query looks like this:

$queryBuilder->leftJoin(
    Contact::class,
    'contact',
    Join::WITH,
    'CAST(JSON_GET(JSON_GET(visit.data, \'code\'), \'contactId\') AS INT) = contact.id',
)

It is a third party entity and I wanted to use Events::loadClassMetadata to add a index but the following:

$builder = new ClassMetadataBuilder($metadata);
$builder->addIndex(['CAST(JSON_GET(JSON_GET(visit.data, \'code\'), \'contactId\') AS INT)'], 'data_code_contactId_idx');

because it is not a column maybe somebody achieved something like this, without that the ORM is throwing the index away on the next migration.