fix: Improve error message for SQLitePersister #417

burr/core/application.py

@@ -2207,6 +2207,14 @@ def with_state_persister(
         """
         if on_every != "step":
             raise ValueError(f"on_every {on_every} not supported")
+
+        # Check if 'is_initialized' exists and whether it returns False, indicating the persister is uninitialized
+        if hasattr(persister, 'is_initialized'):
+            if not persister.is_initialized():
+                raise RuntimeError(
+                    "RuntimeError: Uninitialized persister. Make sure to call .initialize() before passing it to the ApplicationBuilder"
+                )
+        # If the persister is valid and initialized, add it to lifecycle adapters
         if not isinstance(persister, persistence.BaseStateSaver):
             self.lifecycle_adapters.append(persister)
         else:

burr/core/persistence.py

@@ -88,7 +88,11 @@ class BaseStatePersister(BaseStateLoader, BaseStateSaver, metaclass=ABCMeta):
     Extend this class if you want an easy way to implement custom state storage.
     """
 
-    pass
+    def is_initialized(self) -> bool:
+        """Check if the persister has been initialized. Default behavior is False.
+        Persisters that require initialization can override this method.
+        """
+        return False
 
 
 class PersisterHook(PostRunStepHook):
@@ -164,6 +168,7 @@ def __init__(
             db_path, **connect_kwargs if connect_kwargs is not None else {}
         )
         self.serde_kwargs = serde_kwargs or {}
+        self._initialized = False
 
     def create_table_if_not_exists(self, table_name: str):
         """Helper function to create the table where things are stored if it doesn't exist."""
@@ -192,6 +197,11 @@ def initialize(self):
         """Creates the table if it doesn't exist"""
         # Usage
         self.create_table_if_not_exists(self.table_name)
+        self._initialized = True
+
+    def is_initialized(self) -> bool:
+        """Check if the persister is initialized."""
+        return self._initialized
 
     def list_app_ids(self, partition_key: Optional[str], **kwargs) -> list[str]:
         partition_key = (