Support passing list of pydantic objects as dataframe-like structure #13348
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Pull request overview
This PR adds support for passing lists of Pydantic model instances as dataframe-like structures in Streamlit. The implementation treats lists of Pydantic models similarly to lists of dictionaries, converting them to pandas DataFrames using either the Pydantic v2 model_dump() method or the v1 dict() method for backward compatibility.
Key Changes:
- Added a private helper function
_is_list_of_pydantic_models()to detect lists containing Pydantic model instances - Extended
convert_anything_to_pandas_df()to serialize lists of Pydantic models to DataFrames - Updated
determine_data_format()to classify lists of Pydantic models asLIST_OF_RECORDS
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
lib/streamlit/dataframe_util.py |
Added detection and conversion logic for lists of Pydantic models, following the existing pattern used for Snowpark row lists |
lib/tests/streamlit/data_test_cases.py |
Added integration test case for lists of Pydantic models to the shared test suite, ensuring coverage across all dataframe-accepting components |
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📈 Frontend coverage change detectedThe frontend unit test (vitest) coverage has increased by 0.0500%
🎉 Great job on improving test coverage! |
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📉 Python coverage change detectedThe Python unit test coverage has decreased by 0.0507%
💡 Consider adding more unit tests to maintain or improve coverage. Coverage by files
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2 tasks
krupal-p
reviewed
Dec 14, 2025
lib/streamlit/dataframe_util.py
Outdated
| try: | ||
| first_element = next(iter(data)) | ||
| if has_callable_attr(first_element, "model_dump"): | ||
| return pd.DataFrame([item.model_dump() for item in data]) |
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@lukasmasuch would it be better to use model_dump(mode='json') here. There's a bug in st.dataframe where it incorrectly displays small Decimal values but it's solved when you do mode='json'.
from decimal import Decimal
import streamlit as st
from pydantic import BaseModel
class User(BaseModel):
id: int
name: str
is_active: bool
decimal_val: Decimal
users = [
User(id=5, name="Eve", is_active=True, decimal_val=Decimal("-0.01")),
]
st.write("Model dump python mode")
st.dataframe([user.model_dump() for user in users])
st.write("Model dump json mode")
st.dataframe([user.model_dump(mode="json") for user in users])
st.write("Actual value: Decimal('-0.01'):", Decimal("-0.01"))
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Thanks, good feedback. I changed it to json mode 👍
sfc-gh-bnisco
approved these changes
Dec 22, 2025
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Describe your changes
Add support for passing a list of pydantic objects to
st.dataframe,st.data_editor, charts, options widgets, and wherever else we support dataframe-like structures. 32% of Streamlit apps have pydantic as part of their dependencies and we already support single pydantic objects.GitHub Issue Link (if applicable)
Testing Plan
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By submitting this pull request you agree that all contributions to this project are made under the Apache 2.0 license.