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75 lines
2.5 KiB
Python
75 lines
2.5 KiB
Python
from typing import Dict, List, Optional, cast
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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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class DuckDBLoader(BaseLoader):
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"""Loads a query result from DuckDB 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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database: str = ":memory:",
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read_only: bool = False,
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config: Optional[Dict[str, 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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):
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self.query = query
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self.database = database
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self.read_only = read_only
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self.config = config or {}
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self.page_content_columns = page_content_columns
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self.metadata_columns = metadata_columns
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def load(self) -> List[Document]:
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try:
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import duckdb
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except ImportError:
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raise ValueError(
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"Could not import duckdb python package. "
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"Please install it with `pip install duckdb`."
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)
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docs = []
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with duckdb.connect(
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database=self.database, read_only=self.read_only, config=self.config
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) as con:
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query_result = con.execute(self.query)
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results = query_result.fetchall()
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description = cast(list, query_result.description)
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field_names = [c[0] for c in description]
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if self.page_content_columns is None:
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page_content_columns = field_names
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else:
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page_content_columns = self.page_content_columns
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if self.metadata_columns is None:
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metadata_columns = []
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else:
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metadata_columns = self.metadata_columns
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for result in results:
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page_content = "\n".join(
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f"{column}: {result[field_names.index(column)]}"
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for column in page_content_columns
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)
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metadata = {
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column: result[field_names.index(column)]
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for column in metadata_columns
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}
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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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