Missing Support of Pandas DateFrame saved in MemorySaver Checkpointer?

[Pipasgonzalez]

I have been trying to implement an agent that automatically plots retrieved SQL data and it works good so far (without a checkpointer). However, as soon as I compile the graph with the MemorySaver() checkpointer I get the same error each time after the agent reaches the END node.

Here is the graph:
class WorkFlowManager:
def init(self):
self.sql_agent = SQLAgent()
self.plotter = CustomPlotly()
#self.memory = MemorySaver()

def create_workflow(self):
    workflow = StateGraph(State)

    
    # 1st Step: Check if DB relevant to current question, send to end if irelevant, else continue
    workflow.add_node("identify_tables", self.sql_agent.identify_tables)
    workflow.set_entry_point("identify_tables")
    workflow.add_node("set_irelevant_answer", self.sql_agent.set_irelevant_answer)
    workflow.add_node("get_table_summaries", self.sql_agent.get_table_summaries)
    workflow.add_conditional_edges(
        "identify_tables",
        self.sql_agent.decide_if_relevant,
        {False:"set_irelevant_answer", True: "get_table_summaries"})
    workflow.add_edge("set_irelevant_answer", END)

    # 2nd step: Generate and Execute Query
    workflow.add_node("generate_query", self.sql_agent.generate_query)
    workflow.add_edge("get_table_summaries", "generate_query")
    workflow.add_node("execute_query", self.sql_agent.execute_query)
    workflow.add_edge("generate_query", "execute_query")

    # 3rd Step:
    workflow.add_node("check_length_limit", self.sql_agent.length_limit_reached)
    workflow.add_edge("execute_query", "check_length_limit")
    workflow.add_node("answer_question", self.sql_agent.answer_question)

    # 4th Step: Graphing / Plotting
    workflow.add_node("choose_visualization", self.sql_agent.choose_visualization)
    workflow.add_node("select_labels_line", self.sql_agent.select_labels_line)
    workflow.add_node("select_labels_pie", self.sql_agent.select_labels_pie)
    workflow.add_node("plot_line", self.plotter.plot_line)
    workflow.add_node("plot_pie", self.plotter.plot_pie)


    # Path to end:
    workflow.add_edge("plot_pie", END)
    workflow.add_edge("plot_line", END)
    return workflow

def returnGraph(self):
    return self.create_workflow().compile()
    
Here is the state I use:
class State(TypedDict):
  question: str
  sql_query: str
  sql_output_df: pandas.core.frame.DataFrame
  is_relevant: str
  visualization:str
  tables: list[str]
  table_schemas: list[str]
  plot_description: dict
  plot: Figure
  messages: Annotated[list[AnyMessage], add_messages]
  generation: str
  
  
 Here is the error I get as soon as I compile with a checkpointer like below:
 def returnGraph(self):
    return self.create_workflow().compile(checkpointer=MemorySaver())

raise TypeError(f"Object of type {obj.class.name} is not serializable")

TypeError: Object of type DataFrame is not serializable

I think it is weird that it lets me save in state a plotly graph but not a pandas df? It's not even that big, like 50 rows of data. How can I fixe this, so that the checkpointer does not throw an error when trying to save the DF (as a df) to the state