[langchain]: Outdated Import Statements for Retrievers in Documentation

[bart0401]

Type of issue

issue / bug

Language

Python

Description

Summary

Multiple documentation files contain outdated import statements using from langchain.retrievers import ..., which is incompatible with LangChain 1.0+. According to the v1 migration guide, all retriever imports should now use langchain_classic.retrievers instead.

Impact

23 documentation files contain code examples that will fail when users try to run them with LangChain 1.0+.

Error Users Will Encounter

ImportError: cannot import name 'ContextualCompressionRetriever' from 'langchain.retrievers'

or

ModuleNotFoundError: No module named 'langchain.retrievers'

Affected Files

Document Transformers (7 files)

• /src/oss/python/integrations/document_transformers/cross_encoder_reranker.mdx:61
• /src/oss/python/integrations/document_transformers/openvino_rerank.mdx:294
• /src/oss/python/integrations/document_transformers/voyageai-reranker.mdx:295
• /src/oss/python/integrations/document_transformers/jina_rerank.mdx:68
• /src/oss/python/integrations/document_transformers/volcengine_rerank.mdx:298
• /src/oss/python/integrations/document_transformers/dashscope_rerank.mdx:266
• /src/oss/python/integrations/document_transformers/infinity_rerank.mdx:283

Retrievers (5 files)

• /src/oss/python/integrations/retrievers/merger_retriever.mdx:13
• /src/oss/python/integrations/retrievers/flashrank-reranker.mdx:274
• /src/oss/python/integrations/retrievers/llmlingua.mdx:264
• /src/oss/python/integrations/retrievers/fleet_context.mdx:20
• /src/oss/python/integrations/retrievers/re_phrase.mdx:18

Provider Integrations (11 files)

• /src/oss/python/integrations/providers/chroma.mdx:34
• /src/oss/python/integrations/providers/cohere.mdx:28,143
• /src/oss/python/integrations/providers/ragatouille.mdx:107
• /src/oss/python/integrations/providers/wikipedia.mdx:35
• /src/oss/python/integrations/providers/outline.mdx:23
• /src/oss/python/integrations/providers/vespa.mdx:28
• /src/oss/python/integrations/providers/metal.mdx:18
• /src/oss/python/integrations/providers/breebs.mdx:14
• /src/oss/python/integrations/providers/pubmed.mdx:27
• /src/oss/python/integrations/providers/chaindesk.mdx:18

Callbacks (1 file)

• /src/oss/python/integrations/callbacks/uptrain.mdx:65

Current (Incorrect) Code

# ❌ This DOES NOT work in LangChain 1.0+
from langchain.retrievers import (
    ContextualCompressionRetriever,
    DocumentCompressorPipeline,
    MergerRetriever,
)

Expected (Correct) Code

According to the LangChain v1 migration guide (lines 26, 38-39):

# ✅ This works in LangChain 1.0+
from langchain_classic.retrievers import (
    ContextualCompressionRetriever,
    MergerRetriever,
)
from langchain_classic.retrievers.document_compressors import DocumentCompressorPipeline

Or for ContextualCompressionRetriever specifically, the correct import path is:

# ✅ Alternative correct import (as seen in cohere-reranker.mdx:279-281)
from langchain_classic.retrievers.contextual_compression import (
    ContextualCompressionRetriever,
)

Steps to Reproduce

1. Install LangChain 1.0+ (e.g., pip install langchain>=1.0.0)
2. Try to run any code example from the affected documentation pages
3. Observe ImportError or ModuleNotFoundError

Example: merger_retriever.mdx

Location: Lines 13-16 in /src/oss/python/integrations/retrievers/merger_retriever.mdx

Current code:

from langchain.retrievers import (
    ContextualCompressionRetriever,
    DocumentCompressorPipeline,
    MergerRetriever,
)

Should be:

from langchain_classic.retrievers import (
    ContextualCompressionRetriever,
    MergerRetriever,
)
from langchain_classic.retrievers.document_compressors import DocumentCompressorPipeline

Reference Documentation

The LangChain v1 migration guide clearly states:

Retrievers (e.g. MultiQueryRetriever or anything from the previous langchain.retrievers module)

If you were using any of the following from the langchain package, you'll need to install langchain-classic and update your imports

Suggested Fix

1. Replace all instances of from langchain.retrievers import with from langchain_classic.retrievers import in the affected files
2. Update installation instructions to include: pip install langchain-classic
3. Add a note about LangChain 1.0+ compatibility requirements

Additional Context

• One file already uses the correct import pattern: /src/oss/python/integrations/retrievers/cohere-reranker.mdx:279-281
• Migration guide files (langchain-v1.mdx, releases/langchain-v1.mdx) intentionally show old imports as examples of "what not to do" - these should NOT be changed

Environment

• LangChain Version: 1.0.3+
• Documentation Repository: https://github.com/langchain-ai/docs
• Affected Documentation Section: OSS Python integrations

Search Query Used

grep -r "from langchain\.retrievers import" src/oss/python/

This returns 26 total matches, of which 23 are problematic (3 are in migration guides showing old vs new code).