langchain-ai/langchain

Support structured output with Pydantic models in `langchain-huggingface`

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#32,197 opened on Jul 23, 2025

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 (7 comments) (0 reactions) (1 assignee)Python (136,758 stars) (22,617 forks)batch import
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Description

The documentation indicates that it does, but the PydanticOutputParser is not being utilised.

https://github.com/langchain-ai/langchain/blob/0f39155f62742aeaa71c3993dcaa01e03b73f87e/libs/partners/huggingface/langchain_huggingface/chat_models/huggingface.py#L882

Contributor guide

Tech stack
python
Domain
backendai
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
needs investigation
Prerequisites
PythonLangChainPydantic
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30
Research direction
Examine the linked file at line 882 to understand the current output handling without PydanticOutputParser. Investigate how other LangChain chat models (e.g., ChatOpenAI) implement structured output with Pydantic models. Check the comments for any maintainer guidance on expected implementation. Consider adding PydanticOutputParser integration akin to the existing pattern in the codebase.