This change introduces PostgreSQL compatibility, by implementing the
following changes:
* Use `JSONB` instead of `JSON` for PostgreSQL databases. This is
achieved by creating a custom `CustomJSON` type that uses `JSONB` on
PostgreSQL and `JSON` on other databases, leveraging the variant
mechanism of SQLAlchemy.
* Add `is_postgresql` function to check if the current database is
PostgreSQL. Commonly used for migrations, but can be used to determine
how to build queries based on the database engine.
* Add `json_array_contains_value` function to check if a JSON array
includes a specific value. This function is needed as it's
engine-specific.
Support for PostgreSQL is on a best-effort basis, and it relies on the
community for continued support and testing. The project's main database
is MariaDB.
Closes#667.
This change makes some database columns non-nullable, and includes the
migration to seamlessly upgrade the schema.
It includes:
* User and Platform names
* Every boolean column
