22. Add CharmSpecific fields
The implementation of CharmSpecific callbacks in 24. Implement refresh_snap and 29. Implement pre-refresh checks may require you to add fields to your CharmSpecific class.
| The implementation of the is_compatible callback must not use additional fields |
Since CharmSpecific is a dataclass, use the dataclasses syntax to add fields.
Example: Add _charm field
@dataclasses.dataclass(eq=False)
class PostgreSQLRefresh(charm_refresh.CharmSpecificCommon, abc.ABC):
_charm: "PostgreSQLCharm" (1)
def run_pre_refresh_checks_after_1_unit_refreshed(self) -> None:
if self._charm.backup_in_progress: (2)
# [...]
class PostgreSQLCharm(ops.CharmBase):
def __init__(self, *args):
# [...]
self.refresh = charm_refresh.Kubernetes(
KubernetesPostgreSQLRefresh(
workload_name="PostgreSQL",
charm_name="postgresql-k8s",
oci_resource_name="postgresql-image",
_charm=self, (3)
)
)
# [...]| 1 | Add _charm field |
| 2 | Example usage in CharmSpecific callback |
| 3 | Pass the field in the instantiation of your CharmSpecific class |