fix(flask): missing fig_json error

[Molrn]

related to #428

Problem

When no graph is generated, retrieving a converstation through the history fails as the cache is expecting a fig_json field.
The following error is displayed:

Solution

set fig_json as an optional field instead of a required one for the function VannaFlaskApp.load_question. The conversation is then displayed, followed by an empty graph:

Improvements

It would be good to take into account the possibility of fig being null in the JS displaying the graph so that it shows nothing instead of an epty graph, but as it is in the assets I can't modify it.

[AI-Mart]

Yes, it makes sense for the front-end not to display anything when fig is empty. How should I adjust this code to solve it? It’s a bit troublesome.”

[Molrn]

@AI-Mart in the mean time, you can disable all graph generation by overiding the methods responsible for generation:

import pandas as pd
from plotly import Figure

from vanna.remote import VannaDefault


class VannaModel(VannaDefault):

    def generate_plotly_code(
        self, question: str = None, sql: str = None, df_metadata: str = None, **kwargs
    ) -> str:
        return ""

    def get_plotly_figure(
        self, plotly_code: str, df: pd.DataFrame, dark_mode: bool = True
    ) -> Figure:
        return Figure()

    def should_generate_chart(self, df) -> bool:
        return True

[AI-Mart]

“If there is no chat history information, then instead of showing a blank image, nothing should be displayed at all. Currently, I have set the parameter ‘chart=False’; however, it seems that when ‘fig’ is empty,chat history information it still shows a blank image instead of nothing.”This seems to be a front-end issue, as the backend interface is no longer generating the image.

[Uzda20]

Hello, similar error is displayed for df.

I assume similar approach can be applied for fixing it as for fig_json.

[Molrn]

@Uzda20 it is the same kind of error (cache issue) but definitely not the same source, and not the same way to fix it, because it is not supposed to not be set. If you want to adress it, please create a new issue with details about how to reproduce this error

[Uzda20]

@Molrn Thanks, I will try to reproduce it and add issue description as advised.