Refactor class instantiation and update params with load_from_db_fields

src/backend/langflow/interface/initialize/loading.py

@@ -11,9 +11,6 @@ from langchain.chains.base import Chain
 from langchain.document_loaders.base import BaseLoader
 from langchain_community.vectorstores import VectorStore
 from langchain_core.documents import Document
-from loguru import logger
-from pydantic import ValidationError
-
 from langflow.interface.custom_lists import CUSTOM_NODES
 from langflow.interface.importing.utils import eval_custom_component_code, get_function, import_by_type
 from langflow.interface.initialize.llm import initialize_vertexai
@@ -25,6 +22,8 @@ from langflow.interface.toolkits.base import toolkits_creator
 from langflow.interface.utils import load_file_into_dict
 from langflow.interface.wrappers.base import wrapper_creator
 from langflow.utils import validate
+from loguru import logger
+from pydantic import ValidationError
 
 if TYPE_CHECKING:
     from langflow import CustomComponent
@@ -37,7 +36,9 @@ def build_vertex_in_params(params: Dict) -> Dict:
     return {key: value.build() if isinstance(value, Vertex) else value for key, value in params.items()}
 
 
-async def instantiate_class(node_type: str, base_type: str, params: Dict, user_id=None) -> Any:
+async def instantiate_class(
+    node_type: str, base_type: str, load_from_db_fields: list[str], params: Dict, user_id=None
+) -> Any:
     """Instantiate class from module type and key, and params"""
     params = convert_params_to_sets(params)
     params = convert_kwargs(params)
@@ -49,7 +50,9 @@ async def instantiate_class(node_type: str, base_type: str, params: Dict, user_i
             return custom_node(**params)
     logger.debug(f"Instantiating {node_type} of type {base_type}")
     class_object = import_by_type(_type=base_type, name=node_type)
-    return await instantiate_based_on_type(class_object, base_type, node_type, params, user_id=user_id)
+    return await instantiate_based_on_type(
+        class_object, base_type, node_type, load_from_db_fields, params, user_id=user_id
+    )
 
 
 def convert_params_to_sets(params):
@@ -76,7 +79,7 @@ def convert_kwargs(params):
     return params
 
 
-async def instantiate_based_on_type(class_object, base_type, node_type, params, user_id):
+async def instantiate_based_on_type(class_object, base_type, node_type, load_from_db_fields, params, user_id):
     if base_type == "agents":
         return instantiate_agent(node_type, class_object, params)
     elif base_type == "prompts":
@@ -110,18 +113,32 @@ async def instantiate_based_on_type(class_object, base_type, node_type, params,
     elif base_type == "memory":
         return instantiate_memory(node_type, class_object, params)
     elif base_type == "custom_components":
-        return await instantiate_custom_component(node_type, class_object, params, user_id)
+        return await instantiate_custom_component(node_type, class_object, load_from_db_fields, params, user_id)
     elif base_type == "wrappers":
         return instantiate_wrapper(node_type, class_object, params)
     else:
         return class_object(**params)
 
 
-async def instantiate_custom_component(node_type, class_object, params, user_id):
+def update_params_with_load_from_db_fields(custom_component, params, load_from_db_fields):
+    # For each field in load_from_db_fields, we will check if it's in the params
+    # and if it is, we will get the value from the custom_component.keys(name)
+    # and update the params with the value
+    for field in load_from_db_fields:
+        if field in params:
+            try:
+                params[field] = custom_component.keys(field)
+            except Exception as exc:
+                logger.error(f"Failed to get value for {field} from custom component. Error: {exc}")
+                pass
+    return params
+
+
+async def instantiate_custom_component(node_type, class_object, load_from_db_fields, params, user_id):
     params_copy = params.copy()
     class_object: "CustomComponent" = eval_custom_component_code(params_copy.pop("code"))
     custom_component = class_object(user_id=user_id)
-
+    params_copy = update_params_with_load_from_db_fields(custom_component, params_copy, load_from_db_fields)
     if "retriever" in params_copy and hasattr(params_copy["retriever"], "as_retriever"):
         params_copy["retriever"] = params_copy["retriever"].as_retriever()
 
@@ -497,3 +514,6 @@ def build_prompt_template(prompt, tools):
     }
 
     return prompt
+    return prompt
+    return prompt
+    return prompt