Source code for langchain.retrievers.parent_document_retriever

import uuid
from typing import Any, List, Optional, Sequence

from langchain_core.documents import Document
from langchain_text_splitters import TextSplitter

from langchain.retrievers import MultiVectorRetriever


[docs]class ParentDocumentRetriever(MultiVectorRetriever): """Retrieve small chunks then retrieve their parent documents. When splitting documents for retrieval, there are often conflicting desires: 1. You may want to have small documents, so that their embeddings can most accurately reflect their meaning. If too long, then the embeddings can lose meaning. 2. You want to have long enough documents that the context of each chunk is retained. The ParentDocumentRetriever strikes that balance by splitting and storing small chunks of data. During retrieval, it first fetches the small chunks but then looks up the parent ids for those chunks and returns those larger documents. Note that "parent document" refers to the document that a small chunk originated from. This can either be the whole raw document OR a larger chunk. Examples: .. code-block:: python from langchain_community.embeddings import OpenAIEmbeddings from langchain_community.vectorstores import Chroma from langchain_text_splitters import RecursiveCharacterTextSplitter from langchain.storage import InMemoryStore # This text splitter is used to create the parent documents parent_splitter = RecursiveCharacterTextSplitter(chunk_size=2000, add_start_index=True) # This text splitter is used to create the child documents # It should create documents smaller than the parent child_splitter = RecursiveCharacterTextSplitter(chunk_size=400, add_start_index=True) # The vectorstore to use to index the child chunks vectorstore = Chroma(embedding_function=OpenAIEmbeddings()) # The storage layer for the parent documents store = InMemoryStore() # Initialize the retriever retriever = ParentDocumentRetriever( vectorstore=vectorstore, docstore=store, child_splitter=child_splitter, parent_splitter=parent_splitter, ) """ # noqa: E501 child_splitter: TextSplitter """The text splitter to use to create child documents.""" """The key to use to track the parent id. This will be stored in the metadata of child documents.""" parent_splitter: Optional[TextSplitter] = None """The text splitter to use to create parent documents. If none, then the parent documents will be the raw documents passed in.""" child_metadata_fields: Optional[Sequence[str]] = None """Metadata fields to leave in child documents. If None, leave all parent document metadata. """
[docs] def add_documents( self, documents: List[Document], ids: Optional[List[str]] = None, add_to_docstore: bool = True, **kwargs: Any, ) -> None: """Adds documents to the docstore and vectorstores. Args: documents: List of documents to add ids: Optional list of ids for documents. If provided should be the same length as the list of documents. Can be provided if parent documents are already in the document store and you don't want to re-add to the docstore. If not provided, random UUIDs will be used as ids. add_to_docstore: Boolean of whether to add documents to docstore. This can be false if and only if `ids` are provided. You may want to set this to False if the documents are already in the docstore and you don't want to re-add them. """ if self.parent_splitter is not None: documents = self.parent_splitter.split_documents(documents) if ids is None: doc_ids = [str(uuid.uuid4()) for _ in documents] if not add_to_docstore: raise ValueError( "If ids are not passed in, `add_to_docstore` MUST be True" ) else: if len(documents) != len(ids): raise ValueError( "Got uneven list of documents and ids. " "If `ids` is provided, should be same length as `documents`." ) doc_ids = ids docs = [] full_docs = [] for i, doc in enumerate(documents): _id = doc_ids[i] sub_docs = self.child_splitter.split_documents([doc]) if self.child_metadata_fields is not None: for _doc in sub_docs: _doc.metadata = { k: _doc.metadata[k] for k in self.child_metadata_fields } for _doc in sub_docs: _doc.metadata[self.id_key] = _id docs.extend(sub_docs) full_docs.append((_id, doc)) self.vectorstore.add_documents(docs, **kwargs) if add_to_docstore: self.docstore.mset(full_docs)