Bug Report: langchain-docling Pydantic v2 Compatibility Issue
Summary
langchain-docling fails to import with a TypeError: StringConstraints() takes no arguments when using current versions of docling-core and Pydantic v2.
Environment
Python: 3.9.7
langchain-docling: 1.1.0
docling: 2.69.1
docling-core: 2.60.1
pydantic: 2.12.5
OS: Windows 10
Error Trace
Traceback (most recent call last):
File "D:\arvix_benchmark\load.py", line 1, in
from langchain_docling import DoclingLoader
File "D:\arvix_benchmark\venv\lib\site-packages\langchain_docling_init_.py", line 7, in
from langchain_docling.loader import DoclingLoader
File "D:\arvix_benchmark\venv\lib\site-packages\langchain_docling\loader.py", line 12, in
from docling.chunking import BaseChunk, BaseChunker, HybridChunker
...
File "D:\arvix_benchmark\venv\lib\site-packages\docling_core\search\package.py", line 17, in
class Package(BaseModel, extra="forbid"):
File "D:\arvix_benchmark\venv\lib\site-packages\docling_core\search\package.py", line 24, in Package
version: Annotated[str, StringConstraints(strict=True, pattern=VERSION_PATTERN)] = ...
TypeError: StringConstraints() takes no arguments
Root Cause
In docling_core/search/package.py line 24, the code calls:
StringConstraints(strict=True, pattern=VERSION_PATTERN)
However, in Pydantic v2.12.5, StringConstraints() does not accept positional/keyword arguments in this way. The correct syntax for Pydantic v2 is:
StringConstraints(min_length=1, pattern=VERSION_PATTERN)
or use Field with constraints
Steps to Reproduce
Create a Python 3.9+ environment
Install: pip install langchain-docling pydantic>=2.0
Try to import: from langchain_docling import DoclingLoader
Error occurs
Expected Behavior
langchain-docling should import successfully and be usable with Pydantic v2.x
Actual Behavior
Import fails with TypeError: StringConstraints() takes no arguments
Suggested Fix
Update docling-core to use Pydantic v2 syntax for StringConstraints, or pin pydantic to a compatible version in setup.py/pyproject.toml.
Workaround (if available)
Downgrade to older versions: pip install docling-core==2.48.0 docling==2.18.0
Or use an alternative document loader
Report this to:
https://github.com/langchain-ai/langchain-docling (or relevant repo)
System Info
System Information
OS: Windows
OS Version: 10.0.22631
Python Version: 3.9.7 (default, Sep 16 2021, 16:59:28) [MSC v.1916 64 bit (AMD64)]
Package Information
langchain_core: 0.3.83
langchain: 0.3.27
langsmith: 0.4.37
langchain_docling: 1.1.0
langchain_text_splitters: 0.3.11
Optional packages not installed
langserve
Other Dependencies
async-timeout<5.0.0,>=4.0.0;: Installed. No version info available.
claude-agent-sdk>=0.1.0;: Installed. No version info available.
docling~=2.18: Installed. No version info available.
httpx<1,>=0.23.0: Installed. No version info available.
jsonpatch<2.0.0,>=1.33.0: Installed. No version info available.
langchain-anthropic;: Installed. No version info available.
langchain-aws;: Installed. No version info available.
langchain-azure-ai;: Installed. No version info available.
langchain-cohere;: Installed. No version info available.
langchain-community;: Installed. No version info available.
langchain-core<1.0.0,>=0.3.72: Installed. No version info available.
langchain-core<2.0.0,>=0.3.75: Installed. No version info available.
langchain-core~=0.3.19: Installed. No version info available.
langchain-deepseek;: Installed. No version info available.
langchain-fireworks;: Installed. No version info available.
langchain-google-genai;: Installed. No version info available.
langchain-google-vertexai;: Installed. No version info available.
langchain-groq;: Installed. No version info available.
langchain-huggingface;: Installed. No version info available.
langchain-mistralai;: Installed. No version info available.
langchain-ollama;: Installed. No version info available.
langchain-openai;: Installed. No version info available.
langchain-perplexity;: Installed. No version info available.
langchain-text-splitters<1.0.0,>=0.3.9: Installed. No version info available.
langchain-together;: Installed. No version info available.
langchain-xai;: Installed. No version info available.
langsmith-pyo3>=0.1.0rc2;: Installed. No version info available.
langsmith<1.0.0,>=0.3.45: Installed. No version info available.
langsmith>=0.1.17: Installed. No version info available.
openai-agents>=0.0.3;: Installed. No version info available.
opentelemetry-api>=1.30.0;: Installed. No version info available.
opentelemetry-exporter-otlp-proto-http>=1.30.0;: Installed. No version info available.
opentelemetry-sdk>=1.30.0;: Installed. No version info available.
orjson>=3.9.14;: Installed. No version info available.
packaging<26.0.0,>=23.2.0: Installed. No version info available.
packaging>=23.2: Installed. No version info available.
pydantic<3,>=1: Installed. No version info available.
pydantic<3.0.0,>=2.7.4: Installed. No version info available.
pytest>=7.0.0;: Installed. No version info available.
PyYAML<7.0.0,>=5.3.0: Installed. No version info available.
PyYAML>=5.3: Installed. No version info available.
requests-toolbelt>=1.0.0: Installed. No version info available.
requests<3,>=2: Installed. No version info available.
requests>=2.0.0: Installed. No version info available.
rich>=13.9.4;: Installed. No version info available.
SQLAlchemy<3,>=1.4: Installed. No version info available.
tenacity!=8.4.0,<10.0.0,>=8.1.0: Installed. No version info available.
typing-extensions<5.0.0,>=4.7.0: Installed. No version info available.
uuid-utils<1.0,>=0.12.0: Installed. No version info available.
vcrpy>=7.0.0;: Installed. No version info available.
zstandard>=0.23.0: Installed. No version info available.
Bug Report: langchain-docling Pydantic v2 Compatibility Issue
Summary
langchain-docling fails to import with a TypeError: StringConstraints() takes no arguments when using current versions of docling-core and Pydantic v2.
Environment
Python: 3.9.7
langchain-docling: 1.1.0
docling: 2.69.1
docling-core: 2.60.1
pydantic: 2.12.5
OS: Windows 10
Error Trace
Traceback (most recent call last):
File "D:\arvix_benchmark\load.py", line 1, in
from langchain_docling import DoclingLoader
File "D:\arvix_benchmark\venv\lib\site-packages\langchain_docling_init_.py", line 7, in
from langchain_docling.loader import DoclingLoader
File "D:\arvix_benchmark\venv\lib\site-packages\langchain_docling\loader.py", line 12, in
from docling.chunking import BaseChunk, BaseChunker, HybridChunker
...
File "D:\arvix_benchmark\venv\lib\site-packages\docling_core\search\package.py", line 17, in
class Package(BaseModel, extra="forbid"):
File "D:\arvix_benchmark\venv\lib\site-packages\docling_core\search\package.py", line 24, in Package
version: Annotated[str, StringConstraints(strict=True, pattern=VERSION_PATTERN)] = ...
TypeError: StringConstraints() takes no arguments
Root Cause
In docling_core/search/package.py line 24, the code calls:
StringConstraints(strict=True, pattern=VERSION_PATTERN)
However, in Pydantic v2.12.5, StringConstraints() does not accept positional/keyword arguments in this way. The correct syntax for Pydantic v2 is:
StringConstraints(min_length=1, pattern=VERSION_PATTERN)
or use Field with constraints
Steps to Reproduce
Create a Python 3.9+ environment
Install: pip install langchain-docling pydantic>=2.0
Try to import: from langchain_docling import DoclingLoader
Error occurs
Expected Behavior
langchain-docling should import successfully and be usable with Pydantic v2.x
Actual Behavior
Import fails with TypeError: StringConstraints() takes no arguments
Suggested Fix
Update docling-core to use Pydantic v2 syntax for StringConstraints, or pin pydantic to a compatible version in setup.py/pyproject.toml.
Workaround (if available)
Downgrade to older versions: pip install docling-core==2.48.0 docling==2.18.0
Or use an alternative document loader
Report this to:
https://github.com/langchain-ai/langchain-docling (or relevant repo)
System Info
System Information
OS: Windows
OS Version: 10.0.22631
Python Version: 3.9.7 (default, Sep 16 2021, 16:59:28) [MSC v.1916 64 bit (AMD64)]
Package Information
langchain_core: 0.3.83
langchain: 0.3.27
langsmith: 0.4.37
langchain_docling: 1.1.0
langchain_text_splitters: 0.3.11
Optional packages not installed
langserve
Other Dependencies
async-timeout<5.0.0,>=4.0.0;: Installed. No version info available.
claude-agent-sdk>=0.1.0;: Installed. No version info available.
docling~=2.18: Installed. No version info available.
httpx<1,>=0.23.0: Installed. No version info available.
jsonpatch<2.0.0,>=1.33.0: Installed. No version info available.
langchain-anthropic;: Installed. No version info available.
langchain-aws;: Installed. No version info available.
langchain-azure-ai;: Installed. No version info available.
langchain-cohere;: Installed. No version info available.
langchain-community;: Installed. No version info available.
langchain-core<1.0.0,>=0.3.72: Installed. No version info available.
langchain-core<2.0.0,>=0.3.75: Installed. No version info available.
langchain-core~=0.3.19: Installed. No version info available.
langchain-deepseek;: Installed. No version info available.
langchain-fireworks;: Installed. No version info available.
langchain-google-genai;: Installed. No version info available.
langchain-google-vertexai;: Installed. No version info available.
langchain-groq;: Installed. No version info available.
langchain-huggingface;: Installed. No version info available.
langchain-mistralai;: Installed. No version info available.
langchain-ollama;: Installed. No version info available.
langchain-openai;: Installed. No version info available.
langchain-perplexity;: Installed. No version info available.
langchain-text-splitters<1.0.0,>=0.3.9: Installed. No version info available.
langchain-together;: Installed. No version info available.
langchain-xai;: Installed. No version info available.
langsmith-pyo3>=0.1.0rc2;: Installed. No version info available.
langsmith<1.0.0,>=0.3.45: Installed. No version info available.
langsmith>=0.1.17: Installed. No version info available.
openai-agents>=0.0.3;: Installed. No version info available.
opentelemetry-api>=1.30.0;: Installed. No version info available.
opentelemetry-exporter-otlp-proto-http>=1.30.0;: Installed. No version info available.
opentelemetry-sdk>=1.30.0;: Installed. No version info available.
orjson>=3.9.14;: Installed. No version info available.
packaging<26.0.0,>=23.2.0: Installed. No version info available.
packaging>=23.2: Installed. No version info available.
pydantic<3,>=1: Installed. No version info available.
pydantic<3.0.0,>=2.7.4: Installed. No version info available.
pytest>=7.0.0;: Installed. No version info available.
PyYAML<7.0.0,>=5.3.0: Installed. No version info available.
PyYAML>=5.3: Installed. No version info available.
requests-toolbelt>=1.0.0: Installed. No version info available.
requests<3,>=2: Installed. No version info available.
requests>=2.0.0: Installed. No version info available.
rich>=13.9.4;: Installed. No version info available.
SQLAlchemy<3,>=1.4: Installed. No version info available.
tenacity!=8.4.0,<10.0.0,>=8.1.0: Installed. No version info available.
typing-extensions<5.0.0,>=4.7.0: Installed. No version info available.
uuid-utils<1.0,>=0.12.0: Installed. No version info available.
vcrpy>=7.0.0;: Installed. No version info available.
zstandard>=0.23.0: Installed. No version info available.