Setting things up so it's easy to switch databases using a local configuration file (still works with environment variables)

Swtiched from a "joinedload" to a "selectinload" which removes a problem with groupby columns in Postgres and sqlite. (https://docs.sqlalchemy.org/en/14/orm/loading_relationships.html#selectin-eager-loading)

src/spiffworkflow_backend/config/__init__.py

@@ -14,13 +14,13 @@ class ConfigurationError(Exception):
 
 def setup_database_uri(app: Flask) -> None:
     """Setup_database_uri."""
-    if os.environ.get("SPIFFWORKFLOW_BACKEND_DATABASE_URI") is None:
+    if app.config.get("SPIFFWORKFLOW_BACKEND_DATABASE_URI") is None:
         database_name = f"spiffworkflow_backend_{app.config['ENV_IDENTIFIER']}"
-        if os.environ.get("SPIFF_DATABASE_TYPE") == "sqlite":
+        if app.config.get("SPIFF_DATABASE_TYPE") == "sqlite":
             app.config[
                 "SQLALCHEMY_DATABASE_URI"
             ] = f"sqlite:///{app.instance_path}/db_{app.config['ENV_IDENTIFIER']}.sqlite3"
-        elif os.environ.get("SPIFF_DATABASE_TYPE") == "postgres":
+        elif app.config.get("SPIFF_DATABASE_TYPE") == "postgres":
             app.config[
                 "SQLALCHEMY_DATABASE_URI"
             ] = f"postgresql://spiffworkflow_backend:spiffworkflow_backend@localhost:5432/{database_name}"
@@ -33,7 +33,7 @@ def setup_database_uri(app: Flask) -> None:
                 "SQLALCHEMY_DATABASE_URI"
             ] = f"mysql+mysqlconnector://root:{db_pswd}@localhost/{database_name}"
     else:
-        app.config["SQLALCHEMY_DATABASE_URI"] = os.environ.get(
+        app.config["SQLALCHEMY_DATABASE_URI"] = app.config.get(
             "SPIFFWORKFLOW_BACKEND_DATABASE_URI"
         )
 
@@ -73,9 +73,6 @@ def setup_config(app: Flask) -> None:
     else:
         app.config.from_pyfile(f"{app.instance_path}/config.py", silent=True)
 
-    setup_database_uri(app)
-    setup_logger(app)
-
     app.config["PERMISSIONS_FILE_FULLPATH"] = None
     if app.config["SPIFFWORKFLOW_BACKEND_PERMISSIONS_FILE_NAME"]:
         app.config["PERMISSIONS_FILE_FULLPATH"] = os.path.join(
@@ -92,5 +89,8 @@ def setup_config(app: Flask) -> None:
     if app.config["BPMN_SPEC_ABSOLUTE_DIR"] is None:
         raise ConfigurationError("BPMN_SPEC_ABSOLUTE_DIR config must be set")
 
+    setup_database_uri(app)
+    setup_logger(app)
+
     thread_local_data = threading.local()
     app.config["THREAD_LOCAL_DATA"] = thread_local_data

src/spiffworkflow_backend/config/default.py

@@ -60,3 +60,7 @@ SENTRY_TRACES_SAMPLE_RATE = environ.get(
 SPIFFWORKFLOW_BACKEND_LOG_LEVEL = environ.get(
     "SPIFFWORKFLOW_BACKEND_LOG_LEVEL", default="info"
 )
+
+# Datbase Configuration
+SPIFF_DATABASE_TYPE =environ.get("SPIFF_DATABASE_TYPE", default="mysql")  # can also be sqlite, postgres
+SPIFFWORKFLOW_BACKEND_DATABASE_URI=environ.get("SPIFFWORKFLOW_BACKEND_DATABASE_URI", default=None) # Overide above with specific sqlalchymy connection string.

src/spiffworkflow_backend/routes/process_api_blueprint.py

@@ -30,7 +30,7 @@ from SpiffWorkflow.task import TaskState
 from sqlalchemy import and_
 from sqlalchemy import asc
 from sqlalchemy import desc
-from sqlalchemy.orm import joinedload
+from sqlalchemy.orm import selectinload
 
 from spiffworkflow_backend.exceptions.process_entity_not_found_error import (
     ProcessEntityNotFoundError,
@@ -814,7 +814,7 @@ def process_instance_list(
     process_instance_query = ProcessInstanceModel.query
     # Always join that hot user table for good performance at serialization time.
     process_instance_query = process_instance_query.options(
-        joinedload(ProcessInstanceModel.process_initiator)
+        selectinload(ProcessInstanceModel.process_initiator)
     )
 
     if report_filter.process_model_identifier is not None:
@@ -928,13 +928,16 @@ def process_instance_list(
             UserGroupAssignmentModel.user_id == g.user.id
         )
 
-    process_instances = (
-        process_instance_query.group_by(ProcessInstanceModel.id)
-        .order_by(
-            ProcessInstanceModel.start_in_seconds.desc(), ProcessInstanceModel.id.desc()  # type: ignore
+    try:
+        process_instances = (
+            process_instance_query.group_by(ProcessInstanceModel.id)
+            .order_by(
+                ProcessInstanceModel.start_in_seconds.desc(), ProcessInstanceModel.id.desc()  # type: ignore
+            )
+            .paginate(page=page, per_page=per_page, error_out=False)
         )
-        .paginate(page=page, per_page=per_page, error_out=False)
-    )
+    except Exception as e:
+        print(e)
 
     results = list(
         map(