chore(PR): Fixes

src/charm_types.py

@@ -44,39 +44,6 @@ class DatasourcePostgreSQL(BaseModel):
     db: str = Field(min_length=1, description="Database name")
     uri: str = Field(min_length=1, description="Database connection URI")
 
-    @classmethod
-    def from_relation(cls, model: ops.Model, relation: ops.Relation) -> "DatasourcePostgreSQL":
-        """Create a DatasourcePostgreSQL from a relation.
-
-        Args:
-            relation: The relation to get the data from.
-            model: The model to get the secret from.
-
-        Returns:
-            A DatasourcePostgreSQL instance.
-        """
-        relation_data = relation.data[relation.app]
-        user = relation_data.get("username", "")
-        password = relation_data.get("password", "")
-        secret_user = relation_data.get("secret-user", "")
-        if user == "" and secret_user != "":  # nosec
-            secret = model.get_secret(id=secret_user)
-            secret_fields = ops.Secret.get_content(secret)
-            user = secret_fields["username"]
-            password = secret_fields["password"]
-        host, port = relation_data.get("endpoints", ":").split(":")
-        db = relation_data.get("database", "")
-        uri = f"postgres://{user}:{password}@{host}:{port}/{db}"
-
-        return DatasourcePostgreSQL(
-            user=user,
-            password=password,
-            host=host,
-            port=port,
-            db=db,
-            uri=uri,
-        )
-
 
 class CharmConfig(BaseModel):
     """A named tuple representing an IRC configuration.

src/database_observer.py

@@ -56,10 +56,40 @@ def get_db(self) -> typing.Optional[DatasourcePostgreSQL]:
         Returns:
             DatasourcePostgreSQL: The datasource model.
         """
-        # not using get_relation due this issue
-        # https://github.com/canonical/operator/issues/1153
-        if not self.model.relations.get(self.database.relation_name):
+        relation_data = list(
+            self.database.fetch_relation_data(
+                fields=["uris", "endpoints", "username", "password", "database"]
+            ).values()
+        )
+
+        if not relation_data:
+            return None
+
+        # There can be only one database integrated at a time
+        # with the same interface name. See: metadata.yaml
+        data = relation_data[0]
+
+        # Check that the relation data is well formed according to the following json_schema:
+        # https://github.com/canonical/charm-relation-interfaces/blob/main/interfaces/mysql_client/v0/schemas/provider.json
+        if not all(data.get(key) for key in ("endpoints", "username", "password")):
             return None
 
-        relation = self.model.get_relation(self.relation_name)
-        return DatasourcePostgreSQL.from_relation(self.model, relation)
+        database_name = data.get("database", self.database.database)
+        endpoint = data["endpoints"].split(",")[0]
+        user = data["username"]
+        password = data["password"]
+        host, port = endpoint.split(":")
+
+        if "uris" in data:
+            uri = data["uris"].split(",")[0]
+        else:
+            uri = f"postgres://{user}:{password}@{endpoint}/{database_name}"
+
+        return DatasourcePostgreSQL(
+            user=user,
+            password=password,
+            host=host,
+            port=port,
+            db=database_name,
+            uri=uri,
+        )

tests/unit/test_database_observer.py

@@ -96,7 +96,28 @@ def test_get_db_when_no_relation_data():
     """
     harness = Harness(ObservedCharm, meta=REQUIRER_METADATA)
     harness.begin()
-    harness.add_relation("database", "database-provider")
+    harness.add_relation("database", "database-provider", app_data={})
+
+    assert harness.charm.database.get_db() is None
+
+
+def test_get_db_when_invalid_relation_data():
+    """
+    arrange: set up a charm and a database relation with invalid databag.
+    act:.
+    assert: it raises a validation error.
+    """
+    harness = Harness(ObservedCharm, meta=REQUIRER_METADATA)
+    harness.begin()
+    harness.add_relation(
+        "database",
+        "database-provider",
+        app_data={
+            "database": "ircbridge",
+            "endpoints": "postgresql-k8s-primary.local:5432",
+            "password": "",
+            "username": "", 
+        },
+    )
 
-    with pytest.raises(ValidationError):
-        harness.charm.database.get_db()  # pylint: disable=pointless-statement
+    assert harness.charm.database.get_db() is None