app.py

"""
Minimal reproduction of gr.HTML subclass bug with gr.Examples caching.

Bug: When subclassing gr.HTML and using the custom component as an output 
in gr.Examples with cache_examples=True, Gradio throws:
    AttributeError: 'CustomHTMLComponent' object has no attribute 'info'

The error occurs in gradio/components/base.py line 252 in get_config():
    if self.info:

This happens during example caching when Gradio tries to serialize the 
component's config.

Environment: Gradio 6.x (tested with latest)

To reproduce:
1. Run this app: python app.py
2. Click on any example
3. Observe the error in the terminal

Workaround: Use gr.HTML directly via factory function instead of subclassing,
and don't include the custom component in Examples outputs.
"""

import gradio as gr


# Custom component that subclasses gr.HTML - THIS CAUSES THE BUG
class CustomSlider(gr.HTML):
    """A simple custom slider component using gr.HTML templates."""
    
    def __init__(self, value=50, **kwargs):
        html_template = """
        <div style="padding: 20px; background: #f0f0f0; border-radius: 8px;">
            <h3>Custom Slider: {{value}}</h3>
            <input type="range" min="0" max="100" value="{{value}}" 
                   style="width: 100%;" id="custom-slider">
        </div>
        """
        
        js_on_load = """
        (() => {
            const slider = element.querySelector('#custom-slider');
            slider.addEventListener('input', (e) => {
                props.value = parseInt(e.target.value);
            });
            slider.addEventListener('change', (e) => {
                trigger('change', parseInt(e.target.value));
            });
        })();
        """
        
        super().__init__(
            value=value,
            html_template=html_template,
            js_on_load=js_on_load,
            **kwargs
        )
    
    # Even adding api_info() doesn't fix the 'info' attribute error
    def api_info(self):
        return {"type": "integer", "minimum": 0, "maximum": 100}


def process(text_input, slider_value):
    """Simple processing function that returns text and updates the custom slider."""
    result_text = f"Processed: {text_input} with value {slider_value}"
    new_slider_value = slider_value  # Return the same value to update custom component
    return result_text, new_slider_value


with gr.Blocks() as demo:
    gr.Markdown("""
    ## Bug Reproduction: gr.HTML Subclass with Examples Caching
    
    Click any example below to trigger the error:
    ```
    AttributeError: 'CustomSlider' object has no attribute 'info'
    ```
    """)
    
    with gr.Row():
        with gr.Column():
            text_input = gr.Textbox(label="Text Input", value="Hello")
            slider_input = gr.Slider(label="Slider", minimum=0, maximum=100, value=50)
            btn = gr.Button("Process")
        
        with gr.Column():
            text_output = gr.Textbox(label="Output")
            # Custom component that causes the bug when used in Examples outputs
            custom_slider = CustomSlider(value=50, label="Custom Slider Output")
    
    btn.click(
        fn=process,
        inputs=[text_input, slider_input],
        outputs=[text_output, custom_slider]
    )
    
    # THIS CAUSES THE BUG - including custom gr.HTML subclass in outputs with caching
    gr.Examples(
        examples=[
            ["Example 1", 25],
            ["Example 2", 50],
            ["Example 3", 75],
        ],
        inputs=[text_input, slider_input],
        outputs=[text_output, custom_slider],  # Bug: custom_slider causes AttributeError
        fn=process,
        cache_examples=True,  # Bug only occurs with caching enabled
    )

if __name__ == "__main__":
    demo.launch()