Fixing Streamlit `plotly_chart` Deprecation Warnings
Understanding the Streamlit plotly_chart Deprecation Warning
Have you recently encountered a pesky deprecation warning when using st.plotly_chart in your Streamlit applications, especially when trying to set the chart's width or height? You're not alone! Many developers have noticed this warning pop up, even when they're confident they're using officially documented parameters like width="content". This can be quite frustrating, making you wonder if you've done something wrong or if the framework is acting up. Let's dive into what this warning means, why it’s appearing, and how it impacts your development workflow. The core of the issue lies in how Streamlit is handling keyword arguments (kwargs) passed to st.plotly_chart, particularly after recent updates aimed at refining its API.
Streamlit is designed to make data app development incredibly fast and intuitive, but sometimes, API changes and deprecations can throw a wrench into our well-oiled machines. This specific plotly_chart kwargs deprecation warning indicates that certain keyword arguments you might be passing are no longer the recommended way to configure your Plotly charts within a Streamlit app. Previously, it was common to pass a variety of parameters directly to st.plotly_chart that would then be forwarded to the underlying Plotly.js library or processed by Streamlit itself. However, to create a more consistent and maintainable API, Streamlit is moving towards a more structured approach, pushing Plotly-specific configurations into a dedicated config argument. The confusion arises when a parameter like width="content" – which feels like a Streamlit-specific layout control – gets caught in this kwargs deprecation net.
This isn't just a minor notification; it signals a change in how Streamlit expects you to interact with its plotting functions. While your application might still run with the warning for now, ignoring deprecation warnings isn't a good long-term strategy. Future versions of Streamlit could remove the deprecated functionality entirely, leading to broken applications. The current behavior is indeed a regression for many users, as st.plotly_chart with width="content" (or similar sizing parameters) used to work perfectly fine without any warnings in previous versions. This means that code that was once clean and functional is now flagging warnings, prompting developers to refactor their approach. Understanding the underlying reasons for this change and adopting the new best practices is crucial for keeping your Streamlit applications robust and up-to-date.
The Root Cause: Why Are We Seeing This Warning?
The root cause of the plotly_chart kwargs deprecation warning stems from a deliberate effort by the Streamlit team to streamline the API for st.plotly_chart. Historically, st.plotly_chart was quite flexible, accepting a broad range of keyword arguments (kwargs) which it would then try to interpret either as its own parameters or pass them down to the underlying Plotly.js configuration. While this offered a lot of flexibility, it could also lead to ambiguity and make it harder to evolve the API without breaking existing code or introducing unexpected behavior. To address this, Streamlit introduced a significant change: centralizing Plotly-specific configuration options within a dedicated config dictionary parameter.
The snippet of code you highlighted, if kwargs: show_deprecation_warning(...), is at the heart of the matter. This conditional check literally looks to see if any keyword arguments beyond its explicitly defined parameters are being passed. If it finds any, it triggers the deprecation warning, nudging developers to move those kwargs into the config dictionary. The problem, as many users have pointed out, is that parameters like width (especially when set to `
