Fix bug when running LLM alone

Fix #117

src/backend/langflow/graph/graph.py

@@ -62,7 +62,12 @@ class Graph:
             if isinstance(node, ToolkitNode):
                 node.params["llm"] = llm_node
         # remove invalid nodes
-        self.nodes = [node for node in self.nodes if self._validate_node(node)]
+        self.nodes = [
+            node
+            for node in self.nodes
+            if self._validate_node(node)
+            or (len(self.nodes) == 1 and len(self.edges) == 0)
+        ]
 
     def _validate_node(self, node: Node) -> bool:
         # All nodes that do not have edges are invalid

src/backend/langflow/interface/run.py

@@ -191,9 +191,12 @@ def get_result_and_thought_using_graph(langchain_object, message: str):
         if hasattr(langchain_object, "memory") and langchain_object.memory is not None:
             memory_key = langchain_object.memory.memory_key
 
-        for key in langchain_object.input_keys:
+        if hasattr(langchain_object, "input_keys"):
-            if key not in [memory_key, "chat_history"]:
+            for key in langchain_object.input_keys:
-                chat_input = {key: message}
+                if key not in [memory_key, "chat_history"]:
+                    chat_input = {key: message}
+        else:
+            chat_input = message  # type: ignore
 
         if hasattr(langchain_object, "return_intermediate_steps"):
             # https://github.com/hwchase17/langchain/issues/2068

src/backend/langflow/utils/payload.py

@@ -33,6 +33,10 @@ def get_root_node(graph):
     Returns the root node of the template.
     """
     incoming_edges = {edge.source for edge in graph.edges}
+
+    if not incoming_edges and len(graph.nodes) == 1:
+        return graph.nodes[0]
+
     return next((node for node in graph.nodes if node not in incoming_edges), None)