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community[minor]: Add Cassandra document loader (#16215)
- **Description:** document loader for Apache Cassandra - **Twitter handle:** cbornet_
This commit is contained in:
Christophe Bornet
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GitHub
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fc84083ce5
commit
3ccbe11363
123
libs/community/langchain_community/document_loaders/cassandra.py
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123
libs/community/langchain_community/document_loaders/cassandra.py
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@@ -0,0 +1,123 @@
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import json
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from typing import (
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TYPE_CHECKING,
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Any,
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Callable,
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Iterator,
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List,
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Optional,
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Sequence,
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Union,
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)
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from langchain_core.documents import Document
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from langchain_community.document_loaders.base import BaseLoader
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def default_page_content_mapper(row: Any) -> str:
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if hasattr(row, "_asdict"):
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return json.dumps(row._asdict())
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return json.dumps(row)
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_NOT_SET = object()
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if TYPE_CHECKING:
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from cassandra.cluster import Session
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from cassandra.pool import Host
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from cassandra.query import Statement
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class CassandraLoader(BaseLoader):
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def __init__(
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self,
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table: Optional[str] = None,
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session: Optional["Session"] = None,
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keyspace: Optional[str] = None,
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query: Optional[Union[str, "Statement"]] = None,
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page_content_mapper: Callable[[Any], str] = default_page_content_mapper,
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metadata_mapper: Callable[[Any], dict] = lambda _: {},
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*,
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query_parameters: Union[dict, Sequence] = None,
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query_timeout: Optional[float] = _NOT_SET,
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query_trace: bool = False,
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query_custom_payload: dict = None,
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query_execution_profile: Any = _NOT_SET,
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query_paging_state: Any = None,
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query_host: "Host" = None,
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query_execute_as: str = None,
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) -> None:
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"""
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Document Loader for Apache Cassandra.
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Args:
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table: The table to load the data from.
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(do not use together with the query parameter)
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session: The cassandra driver session.
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If not provided, the cassio resolved session will be used.
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keyspace: The keyspace of the table.
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If not provided, the cassio resolved keyspace will be used.
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query: The query used to load the data.
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(do not use together with the table parameter)
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page_content_mapper: a function to convert a row to string page content.
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query_parameters: The query parameters used when calling session.execute .
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query_timeout: The query timeout used when calling session.execute .
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query_custom_payload: The query custom_payload used when calling
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session.execute .
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query_execution_profile: The query execution_profile used when calling
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session.execute .
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query_host: The query host used when calling session.execute .
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query_execute_as: The query execute_as used when calling session.execute .
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"""
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if query and table:
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raise ValueError("Cannot specify both query and table.")
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if not query and not table:
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raise ValueError("Must specify query or table.")
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if not session or (table and not keyspace):
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try:
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from cassio.config import check_resolve_keyspace, check_resolve_session
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except (ImportError, ModuleNotFoundError):
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raise ImportError(
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"Could not import a recent cassio package."
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"Please install it with `pip install --upgrade cassio`."
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)
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if table:
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_keyspace = keyspace or check_resolve_keyspace(keyspace)
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self.query = f"SELECT * FROM {_keyspace}.{table};"
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self.metadata = {"table": table, "keyspace": _keyspace}
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else:
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self.query = query
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self.metadata = {}
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self.session = session or check_resolve_session(session)
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self.page_content_mapper = page_content_mapper
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self.metadata_mapper = metadata_mapper
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self.query_kwargs = {
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"parameters": query_parameters,
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"trace": query_trace,
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"custom_payload": query_custom_payload,
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"paging_state": query_paging_state,
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"host": query_host,
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"execute_as": query_execute_as,
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}
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if query_timeout is not _NOT_SET:
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self.query_kwargs["timeout"] = query_timeout
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if query_execution_profile is not _NOT_SET:
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self.query_kwargs["execution_profile"] = query_execution_profile
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def load(self) -> List[Document]:
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return list(self.lazy_load())
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def lazy_load(self) -> Iterator[Document]:
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for row in self.session.execute(self.query, **self.query_kwargs):
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metadata = self.metadata.copy()
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metadata.update(self.metadata_mapper(row))
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yield Document(
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page_content=self.page_content_mapper(row), metadata=metadata
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)
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@@ -14,6 +14,13 @@ ASTRA_DB_APPLICATION_TOKEN=AstraCS:your_astra_db_application_token
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# ASTRA_DB_KEYSPACE=your_astra_db_namespace
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# cassandra
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CASSANDRA_CONTACT_POINTS=127.0.0.1
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# CASSANDRA_USERNAME=your_cassandra_username
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# CASSANDRA_PASSWORD=your_cassandra_password
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# CASSANDRA_KEYSPACE=your_cassandra_keyspace
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# pinecone
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# your api key from left menu "API Keys" in https://app.pinecone.io
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PINECONE_API_KEY=your_pinecone_api_key_here
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@@ -0,0 +1,121 @@
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"""
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Test of Cassandra document loader class `CassandraLoader`
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"""
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import os
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from typing import Any
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import pytest
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from langchain_core.documents import Document
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from langchain_community.document_loaders.cassandra import CassandraLoader
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CASSANDRA_DEFAULT_KEYSPACE = "docloader_test_keyspace"
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CASSANDRA_TABLE = "docloader_test_table"
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@pytest.fixture(autouse=True, scope="session")
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def keyspace() -> str:
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import cassio
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from cassandra.cluster import Cluster
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from cassio.config import check_resolve_session, resolve_keyspace
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from cassio.table.tables import PlainCassandraTable
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if any(
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env_var in os.environ
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for env_var in [
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"CASSANDRA_CONTACT_POINTS",
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"ASTRA_DB_APPLICATION_TOKEN",
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"ASTRA_DB_INIT_STRING",
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]
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):
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cassio.init(auto=True)
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session = check_resolve_session()
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else:
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cluster = Cluster()
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session = cluster.connect()
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keyspace = resolve_keyspace() or CASSANDRA_DEFAULT_KEYSPACE
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cassio.init(session=session, keyspace=keyspace)
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session.execute(
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(
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f"CREATE KEYSPACE IF NOT EXISTS {keyspace} "
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f"WITH replication = {{'class': 'SimpleStrategy', 'replication_factor': 1}}"
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)
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)
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# We use a cassio table by convenience to seed the DB
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table = PlainCassandraTable(
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table=CASSANDRA_TABLE, keyspace=keyspace, session=session
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)
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table.put(row_id="id1", body_blob="text1")
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table.put(row_id="id2", body_blob="text2")
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yield keyspace
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session.execute(f"DROP TABLE IF EXISTS {keyspace}.{CASSANDRA_TABLE}")
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def test_loader_table(keyspace: str) -> None:
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loader = CassandraLoader(table=CASSANDRA_TABLE)
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assert loader.load() == [
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Document(
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page_content='{"row_id": "id1", "body_blob": "text1"}',
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metadata={"table": CASSANDRA_TABLE, "keyspace": keyspace},
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),
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Document(
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page_content='{"row_id": "id2", "body_blob": "text2"}',
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metadata={"table": CASSANDRA_TABLE, "keyspace": keyspace},
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),
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]
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def test_loader_query(keyspace: str) -> None:
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loader = CassandraLoader(
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query=f"SELECT body_blob FROM {keyspace}.{CASSANDRA_TABLE}"
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)
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assert loader.load() == [
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Document(page_content='{"body_blob": "text1"}'),
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Document(page_content='{"body_blob": "text2"}'),
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]
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def test_loader_page_content_mapper(keyspace: str) -> None:
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def mapper(row: Any) -> str:
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return str(row.body_blob)
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loader = CassandraLoader(table=CASSANDRA_TABLE, page_content_mapper=mapper)
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assert loader.load() == [
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Document(
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page_content="text1",
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metadata={"table": CASSANDRA_TABLE, "keyspace": keyspace},
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),
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Document(
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page_content="text2",
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metadata={"table": CASSANDRA_TABLE, "keyspace": keyspace},
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),
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]
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def test_loader_metadata_mapper(keyspace: str) -> None:
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def mapper(row: Any) -> dict:
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return {"id": row.row_id}
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loader = CassandraLoader(table=CASSANDRA_TABLE, metadata_mapper=mapper)
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assert loader.load() == [
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Document(
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page_content='{"row_id": "id1", "body_blob": "text1"}',
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metadata={
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"table": CASSANDRA_TABLE,
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"keyspace": keyspace,
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"id": "id1",
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},
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),
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Document(
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page_content='{"row_id": "id2", "body_blob": "text2"}',
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metadata={
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"table": CASSANDRA_TABLE,
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"keyspace": keyspace,
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"id": "id2",
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},
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),
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]
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