Source code for langchain_community.docstore.arbitrary_fn
from typing import Callable, Union
from langchain_core.documents import Document
from langchain_community.docstore.base import Docstore
[docs]class DocstoreFn(Docstore):
"""Docstore via arbitrary lookup function.
This is useful when:
* it's expensive to construct an InMemoryDocstore/dict
* you retrieve documents from remote sources
* you just want to reuse existing objects
"""
[docs] def __init__(
self,
lookup_fn: Callable[[str], Union[Document, str]],
):
self._lookup_fn = lookup_fn
[docs] def search(self, search: str) -> Document:
"""Search for a document.
Args:
search: search string
Returns:
Document if found, else error message.
"""
r = self._lookup_fn(search)
if isinstance(r, str):
# NOTE: assume the search string is the source ID
return Document(page_content=r, metadata={"source": search})
elif isinstance(r, Document):
return r
raise ValueError(f"Unexpected type of document {type(r)}")