Fixing `st.plotly_chart` `kwargs` Deprecation Warnings

by Alex Johnson 55 views

Introduction: Navigating the st.plotly_chart Warning

If you're a Streamlit developer, chances are you've integrated beautiful, interactive visualizations into your web applications using st.plotly_chart. It's a fantastic tool that allows for seamless embedding of Plotly graphs, bringing your data to life with just a few lines of code. However, a recent update has introduced a rather puzzling deprecation warning related to kwargs when using seemingly standard parameters like width="content". This warning, which surfaces even when you're diligently following the documentation, can be quite confusing and might make you wonder if you're doing something wrong. Rest assured, you're not alone, and it's a known issue that many developers are encountering.

This article aims to be your friendly guide through the thicket of this st.plotly_chart kwargs deprecation warning. We'll dive deep into understanding why this warning appears, especially when you're just trying to set the chart's width or height using the recommended width="content" parameter. We'll explore the technical underpinnings of this particular deprecation warning and dissect the code that triggers it. Our goal is to not only clarify the situation but also to provide you with practical insights and temporary workarounds to keep your Streamlit applications running smoothly and your console free from unexpected warnings. We believe in creating high-quality content that provides real value, and for any developer working with Streamlit and Plotly, understanding these nuances is incredibly important for maintaining a clean and efficient codebase. Let's unravel this mystery together and ensure your interactive dashboards remain as stunning as ever, without any annoying interruptions.

This st.plotly_chart kwargs deprecation warning is more than just an aesthetic issue; it can lead to developer confusion, obscure genuinely important warnings, and generally make the development experience less pleasant. Imagine painstakingly building a complex dashboard, only to be greeted by a console full of warnings for code that should be correct. It can be frustrating and counterproductive. That's why addressing this specific kwargs deprecation warning is crucial. We'll walk through the context of Streamlit's evolution, particularly how it handles Plotly integrations and the ongoing efforts to refine its API. Understanding this background will help us appreciate the intent behind certain changes, even if their implementation, in this specific case, has led to an unintended side effect. Our discussion will cover everything from the basic setup of st.plotly_chart to the advanced configurations, ensuring you have a comprehensive understanding of how to manage Plotly charts within your Streamlit applications efficiently. By the end of this guide, you'll be well-equipped to handle this warning and proactively manage similar situations in your future projects, making your Streamlit development journey smoother and more enjoyable.

The Core Problem: Unpacking the kwargs Deprecation

The heart of the matter lies in how st.plotly_chart handles its arguments, particularly the kwargs (keyword arguments) it accepts. The deprecation warning message itself is quite specific: "Variable keyword arguments for st.plotly_chart have been deprecated and will be removed in a future release. Use the config argument instead to specify Plotly configuration options." This message strongly suggests that any unrecognized keyword arguments passed to st.plotly_chart will trigger this warning, guiding developers towards using the dedicated config parameter for Plotly-specific configurations. This is generally a good practice for API design, separating concerns and making the interface cleaner. However, the unexpected twist here is that documented parameters like width (when set to "content") or height are being caught in this kwargs deprecation net, leading to false positives.

Historically, Streamlit has offered various ways to control the size of embedded charts. An earlier approach involved use_container_width=True, which has since been deprecated in favor of a more flexible width argument. The intention behind width="content" is to tell Streamlit to size the chart to fit its parent container, dynamically adjusting as needed. This is a perfectly valid and often desired behavior, clearly outlined in the Streamlit documentation. So, why does passing width="content", a documented and recommended parameter, suddenly trigger a warning about variable keyword arguments? The problem stems from the internal implementation of st.plotly_chart. The code snippet provided in the issue description reveals the culprit:

if kwargs:
    show_deprecation_warning(
        "Variable keyword arguments for st.plotly_chart have been "
        "deprecated and will be removed in a future release. Use the "
        "config argument instead to specify Plotly configuration "
        "options."
    )

This if kwargs: check is designed to catch any leftover, non-explicitly defined keyword arguments passed to the function. Unfortunately, it appears that the width and height parameters, when used with certain string values (like "content"), are not being properly consumed or recognized as distinct, non-kwargs parameters before this generic kwargs check is performed. This means that even though width is a valid argument, it's being treated as an unknown kwarg in this specific scenario, thereby triggering the st.plotly_chart kwargs deprecation warning. This creates a confusing experience because developers are following the explicit instructions in the documentation but are still being flagged with a deprecation notice. The true spirit of the kwargs deprecation is to prevent arbitrary Plotly configuration options from being passed directly, pushing them into the config dictionary, but in this case, it's overreaching and catching valid layout parameters. This discrepancy between the documented usage and the internal warning mechanism is precisely what makes this issue a Streamlit regression and a source of considerable frustration for users seeking to maintain clean Streamlit code without unnecessary console clutter.

Reproducing the st.plotly_chart Deprecation Warning

To truly understand and confirm the st.plotly_chart kwargs deprecation warning, let's walk through the exact reproducible code example provided in the issue. This isn't just a theoretical discussion; this is a live issue that can be easily observed in your own Streamlit development environment, particularly with Streamlit version 1.50.0 and Python 3.14.2 on an Operating System like MacOs 26.1, viewed in a Chrome browser. The steps are straightforward, illustrating precisely how this deprecation warning manifests even when adhering to documented API usage. The simplicity of the code snippet means that many developers might stumble upon this without even realizing the underlying cause.

Here’s the code that reliably triggers the warning:

import plotly.graph_objects as go
import streamlit as st

fig = go.Figure()
fig.add_trace(go.Barpolar(r=[1], theta=[0], width=[120]))
fig.update_layout(width=500, height=360)

st.plotly_chart(fig, width="content")

Let's break down each part of this Streamlit code example to see how it leads to the kwargs deprecation problem. First, we import the necessary libraries: plotly.graph_objects as go for creating our Plotly figure, and streamlit as st for integrating it into our web application. Next, a basic Plotly figure is initialized: fig = go.Figure(). This creates an empty figure object that we can then populate with traces and layout configurations. For this example, a simple Barpolar trace is added using fig.add_trace(go.Barpolar(r=[1], theta=[0], width=[120])). This creates a polar bar chart with a single bar, primarily to ensure there’s some content in the figure. The width=[120] here refers to the width of the bar within the polar chart, not the overall chart width in the Streamlit app.

The next line, fig.update_layout(width=500, height=360), is where we define the intrinsic size of the Plotly chart itself. These width and height values determine the dimensions of the Plotly figure before Streamlit attempts to render it. This is a standard way to control the initial size of your Plotly charts. Finally, the crucial line that triggers the warning is st.plotly_chart(fig, width="content"). Here, we're passing our Plotly figure (fig) to Streamlit's display function. The width="content" argument is intended to instruct Streamlit to make the chart expand to the full width of its container, a common requirement for responsive layouts. This is a documented and expected parameter for st.plotly_chart, designed to replace the now deprecated use_container_width. However, when this code runs, the Streamlit console will output the deprecation warning related to kwargs, indicating that width="content" is being mistakenly interpreted as an unknown variable keyword argument. This perfectly illustrates the st.plotly_chart kwargs deprecation warning issue, making it a clear Streamlit regression where valid input leads to an erroneous warning message, creating unnecessary confusion for developers trying to build responsive Streamlit apps.

Expected vs. Current Behavior: Why This Is a Regression

When developers use a library like Streamlit, there's a fundamental expectation: documented features should work as advertised, without triggering unwarranted warnings or errors. This brings us to the core of why the st.plotly_chart kwargs deprecation warning when using width="content" is not merely an inconvenience but a significant regression. The expected behavior is quite straightforward: when passing width="content" to st.plotly_chart, users anticipate that the chart will render, adjust its size to fit the container as specified, and no deprecation warning should appear in the console. After all, width is a clearly defined, documented parameter for this function, explicitly designed to provide layout control, much like its predecessor use_container_width. It’s part of the public API, and developers are correctly using it according to the official guidelines for Streamlit st.plotly_chart.

However, the current behavior starkly contrasts with this expectation. Despite using a valid and documented parameter, users are consistently greeted with the kwargs deprecation warning. This creates a jarring experience, as the warning message itself explicitly states, "Variable keyword arguments for st.plotly_chart have been deprecated... Use the config argument instead..." This implies that width="content" is being treated as an arbitrary, unrecognized keyword argument, pushing developers towards using the config dictionary, which is not where layout parameters like width or height typically belong for Streamlit's rendering behavior. This misclassification is the crux of the Streamlit regression.

Why is this a regression? Because, as stated in the issue, "Yes, this used to work in a previous version." In earlier Streamlit versions, before the internal kwargs check was implemented or refined in such a way, passing width="content" would function silently and correctly. The introduction of the if kwargs: show_deprecation_warning(...) block, while well-intentioned for other kwargs deprecation scenarios, has inadvertently created a false positive for the width parameter. This means that a previously functional and documented code pattern now produces an erroneous warning. This not only causes confusion but also diminishes developer trust in the API's consistency. When developers see warnings for perfectly valid code, they might start ignoring warnings altogether, potentially missing actual important deprecation notices or errors. Furthermore, this adds unnecessary noise to the development console, making it harder to spot genuine issues that require attention. It's a classic example of an unintended side effect during an API overhaul, making Streamlit development less seamless than it should be. The goal of improving Streamlit plotly_chart parameters handling seems to have missed this specific edge case, causing a step backward in developer experience. This highlights the importance of rigorous testing and consideration of all documented pathways during API changes, especially when dealing with critical components like Plotly integration.

Solutions and Workarounds for the st.plotly_chart Warning

Facing an unexpected st.plotly_chart kwargs deprecation warning can be frustrating, especially when your code is doing exactly what the documentation suggests. Thankfully, while we await a definitive fix from the Streamlit team, there are several solutions and workarounds you can employ to keep your Streamlit applications running smoothly and your console free from these misleading warnings. It's all about understanding how to temporarily bypass the issue or structure your code to avoid triggering the false positive. Implementing these Streamlit workarounds will ensure that your users continue to experience beautiful, responsive Plotly charts without any behind-the-scenes hiccups.

One of the most straightforward temporary workarounds is to avoid using width="content" directly in the st.plotly_chart call for now. Instead, you can achieve similar responsive behavior using other methods. For instance, if you want your chart to simply take up the full available width of its container, the use_container_width=True parameter might still work for some users, although it itself is deprecated in newer versions. However, it's being deprecated specifically in favor of the width and height arguments, making its temporary re-introduction slightly ironic. A more robust solution, especially if you want to control the exact dimensions, is to manage the width and height directly within the Plotly figure's layout, and then let Streamlit handle the rendering without a specific width argument in st.plotly_chart. For example:

import plotly.graph_objects as go
import streamlit as st

fig = go.Figure()
fig.add_trace(go.Barpolar(r=[1], theta=[0], width=[120]))

# Option 1: Set fixed width/height in Plotly layout
# This won't respond to container width, but avoids the warning.
fig.update_layout(width=700, height=400)

st.plotly_chart(fig) # No width="content" here

# Option 2: Use an older method if it still works for your Streamlit version
# st.plotly_chart(fig, use_container_width=True) # This itself is deprecated but might avoid the kwargs warning

# Option 3: Manual sizing with CSS/HTML if embedding directly, but for st.plotly_chart, this is less direct.

The key here is that by not passing width="content" to st.plotly_chart, the if kwargs: check within Streamlit won't be triggered by a misidentified parameter. If width="content" is crucial for your layout, another potential, though slightly more involved, approach involves wrapping your st.plotly_chart call within a st.container() and using CSS for responsiveness, or dynamically calculating the width in Python based on st.columns or other layout components. This requires a bit more custom python development tips but can offer precise control.

For the ideal solution, the Streamlit team needs to adjust the internal logic of st.plotly_chart. Specifically, the kwargs check should be refined to explicitly recognize width and height as valid, non-kwargs parameters when they are passed. This means ensuring that width="content" (and other valid string values for width and height) are processed before the generic if kwargs: check is performed. This would prevent the false positive and align the function's behavior with its documentation, restoring the integrity of Streamlit plotly_chart parameters handling. This kind of fix would eliminate the need for Streamlit workarounds for this specific deprecation warning, leading to clean Streamlit code by default. It’s about careful API design and implementation to avoid misleading deprecation warning fix messages for valid usage, enhancing the overall developer experience and promoting the clear Plotly integration that Streamlit is known for.

A Note on use_container_width

It’s worth a brief moment to reflect on use_container_width. This parameter, which used to be a common way to make Streamlit Plotly charts span the full width of their parent container, has itself been deprecated. The move was a logical step towards a more unified and flexible API, shifting to width="container" or width="content" (depending on the exact desired behavior and context) as the preferred way to achieve responsiveness. This transition, while aimed at improving Streamlit development, has unfortunately coincided with the kwargs deprecation issue discussed here. It highlights the complexities of evolving APIs and the delicate balance required to maintain backward compatibility while introducing better, forward-looking features. While use_container_width=True might still work in some older Streamlit environments, and might even temporarily bypass the kwargs warning, relying on it is not a long-term solution due to its own deprecation status. The ultimate goal is to correctly use the width and height parameters as intended, without erroneous warnings.

Conclusion: Keeping Your Streamlit Apps Warning-Free

In conclusion, the st.plotly_chart kwargs deprecation warning when using width="content" is a notable glitch in an otherwise robust library. While it doesn't break your application, it creates unnecessary noise and confusion, hindering a smooth Streamlit development experience. We've explored how this Streamlit regression occurs due to an overzealous kwargs check, incorrectly flagging a documented parameter. Understanding this mechanism is the first step towards managing it effectively.

By implementing the suggested Streamlit workarounds, such as adjusting where you set your chart's width or temporarily avoiding width="content" in the st.plotly_chart call, you can maintain a clean console and ensure your Plotly charts continue to perform as expected. Ultimately, the ideal deprecation warning fix lies with the Streamlit maintainers, who will hopefully refine the argument parsing to differentiate between valid parameters and true kwargs for Plotly configurations.

Staying updated with library changes, actively participating in the community by reporting issues, and contributing to open-source projects are all vital aspects of modern python development tips. This particular issue serves as a good reminder that even the most mature libraries can have quirks, and a little investigation goes a long way. Keep building amazing responsive Streamlit apps, and don't let a few warnings deter you!

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