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81 lines
3.1 KiB
Python
81 lines
3.1 KiB
Python
from __future__ import annotations
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from typing import TYPE_CHECKING, List, Optional
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from langchain.docstore.document import Document
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from langchain.document_loaders.base import BaseLoader
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if TYPE_CHECKING:
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from google.auth.credentials import Credentials
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class BigQueryLoader(BaseLoader):
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"""Loads a query result from BigQuery into a list of documents.
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Each document represents one row of the result. The `page_content_columns`
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are written into the `page_content` of the document. The `metadata_columns`
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are written into the `metadata` of the document. By default, all columns
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are written into the `page_content` and none into the `metadata`.
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"""
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def __init__(
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self,
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query: str,
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project: Optional[str] = None,
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page_content_columns: Optional[List[str]] = None,
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metadata_columns: Optional[List[str]] = None,
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credentials: Optional[Credentials] = None,
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):
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"""Initialize BigQuery document loader.
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Args:
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query: The query to run in BigQuery.
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project: Optional. The project to run the query in.
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page_content_columns: Optional. The columns to write into the `page_content`
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of the document.
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metadata_columns: Optional. The columns to write into the `metadata` of the
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document.
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credentials : google.auth.credentials.Credentials, optional
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Credentials for accessing Google APIs. Use this parameter to override
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default credentials, such as to use Compute Engine
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(`google.auth.compute_engine.Credentials`) or Service Account
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(`google.oauth2.service_account.Credentials`) credentials directly.
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"""
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self.query = query
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self.project = project
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self.page_content_columns = page_content_columns
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self.metadata_columns = metadata_columns
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self.credentials = credentials
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def load(self) -> List[Document]:
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try:
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from google.cloud import bigquery
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except ImportError as ex:
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raise ValueError(
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"Could not import google-cloud-bigquery python package. "
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"Please install it with `pip install google-cloud-bigquery`."
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) from ex
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bq_client = bigquery.Client(credentials=self.credentials, project=self.project)
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query_result = bq_client.query(self.query).result()
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docs: List[Document] = []
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page_content_columns = self.page_content_columns
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metadata_columns = self.metadata_columns
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if page_content_columns is None:
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page_content_columns = [column.name for column in query_result.schema]
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if metadata_columns is None:
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metadata_columns = []
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for row in query_result:
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page_content = "\n".join(
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f"{k}: {v}" for k, v in row.items() if k in page_content_columns
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)
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metadata = {k: v for k, v in row.items() if k in metadata_columns}
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doc = Document(page_content=page_content, metadata=metadata)
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docs.append(doc)
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return docs
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