mirror of
https://github.com/hwchase17/langchain
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1e80113ac9
The timeout function comes in handy when you want to kill longrunning queries. The value sanitization removes all lists that are larger than 128 elements. The idea here is to remove embedding properties from results.
266 lines
10 KiB
Python
266 lines
10 KiB
Python
from typing import Any, Dict, List, Optional
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from langchain_core.utils import get_from_env
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from langchain_community.graphs.graph_document import GraphDocument
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from langchain_community.graphs.graph_store import GraphStore
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node_properties_query = """
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CALL apoc.meta.data()
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YIELD label, other, elementType, type, property
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WHERE NOT type = "RELATIONSHIP" AND elementType = "node"
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WITH label AS nodeLabels, collect({property:property, type:type}) AS properties
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RETURN {labels: nodeLabels, properties: properties} AS output
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"""
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rel_properties_query = """
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CALL apoc.meta.data()
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YIELD label, other, elementType, type, property
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WHERE NOT type = "RELATIONSHIP" AND elementType = "relationship"
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WITH label AS nodeLabels, collect({property:property, type:type}) AS properties
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RETURN {type: nodeLabels, properties: properties} AS output
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"""
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rel_query = """
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CALL apoc.meta.data()
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YIELD label, other, elementType, type, property
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WHERE type = "RELATIONSHIP" AND elementType = "node"
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UNWIND other AS other_node
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RETURN {start: label, type: property, end: toString(other_node)} AS output
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"""
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def value_sanitize(d: Dict[str, Any]) -> Dict[str, Any]:
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"""
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Sanitizes the input dictionary by removing embedding-like values,
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lists with more than 128 elements, that are mostly irrelevant for
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generating answers in a LLM context. These properties, if left in
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results, can occupy significant context space and detract from
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the LLM's performance by introducing unnecessary noise and cost.
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"""
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LIST_LIMIT = 128
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# Create a new dictionary to avoid changing size during iteration
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new_dict = {}
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for key, value in d.items():
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if isinstance(value, dict):
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# Recurse to handle nested dictionaries
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new_dict[key] = value_sanitize(value)
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elif isinstance(value, list):
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# check if it has less than LIST_LIMIT values
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if len(value) < LIST_LIMIT:
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# if value is a list, check if it contains dictionaries to clean
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cleaned_list = []
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for item in value:
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if isinstance(item, dict):
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cleaned_list.append(value_sanitize(item))
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else:
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cleaned_list.append(item)
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new_dict[key] = cleaned_list
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else:
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new_dict[key] = value
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return new_dict
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class Neo4jGraph(GraphStore):
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"""Provides a connection to a Neo4j database for various graph operations.
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Parameters:
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url (Optional[str]): The URL of the Neo4j database server.
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username (Optional[str]): The username for database authentication.
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password (Optional[str]): The password for database authentication.
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database (str): The name of the database to connect to. Default is 'neo4j'.
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timeout (Optional[float]): The timeout for transactions in seconds.
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Useful for terminating long-running queries.
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By default, there is no timeout set.
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sanitize (bool): A flag to indicate whether to remove lists with
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more than 128 elements from results. Useful for removing
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embedding-like properties from database responses. Default is False.
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*Security note*: Make sure that the database connection uses credentials
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that are narrowly-scoped to only include necessary permissions.
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Failure to do so may result in data corruption or loss, since the calling
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code may attempt commands that would result in deletion, mutation
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of data if appropriately prompted or reading sensitive data if such
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data is present in the database.
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The best way to guard against such negative outcomes is to (as appropriate)
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limit the permissions granted to the credentials used with this tool.
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See https://python.langchain.com/docs/security for more information.
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"""
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def __init__(
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self,
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url: Optional[str] = None,
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username: Optional[str] = None,
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password: Optional[str] = None,
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database: str = "neo4j",
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timeout: Optional[float] = None,
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sanitize: bool = False,
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) -> None:
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"""Create a new Neo4j graph wrapper instance."""
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try:
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import neo4j
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except ImportError:
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raise ValueError(
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"Could not import neo4j python package. "
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"Please install it with `pip install neo4j`."
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)
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url = get_from_env("url", "NEO4J_URI", url)
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username = get_from_env("username", "NEO4J_USERNAME", username)
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password = get_from_env("password", "NEO4J_PASSWORD", password)
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database = get_from_env("database", "NEO4J_DATABASE", database)
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self._driver = neo4j.GraphDatabase.driver(url, auth=(username, password))
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self._database = database
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self.timeout = timeout
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self.sanitize = sanitize
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self.schema: str = ""
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self.structured_schema: Dict[str, Any] = {}
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# Verify connection
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try:
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self._driver.verify_connectivity()
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except neo4j.exceptions.ServiceUnavailable:
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raise ValueError(
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"Could not connect to Neo4j database. "
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"Please ensure that the url is correct"
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)
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except neo4j.exceptions.AuthError:
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raise ValueError(
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"Could not connect to Neo4j database. "
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"Please ensure that the username and password are correct"
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)
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# Set schema
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try:
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self.refresh_schema()
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except neo4j.exceptions.ClientError:
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raise ValueError(
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"Could not use APOC procedures. "
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"Please ensure the APOC plugin is installed in Neo4j and that "
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"'apoc.meta.data()' is allowed in Neo4j configuration "
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)
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@property
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def get_schema(self) -> str:
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"""Returns the schema of the Graph"""
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return self.schema
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@property
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def get_structured_schema(self) -> Dict[str, Any]:
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"""Returns the structured schema of the Graph"""
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return self.structured_schema
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def query(self, query: str, params: dict = {}) -> List[Dict[str, Any]]:
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"""Query Neo4j database."""
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from neo4j import Query
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from neo4j.exceptions import CypherSyntaxError
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with self._driver.session(database=self._database) as session:
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try:
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data = session.run(Query(text=query, timeout=self.timeout), params)
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json_data = [r.data() for r in data]
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if self.sanitize:
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json_data = value_sanitize(json_data)
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return json_data
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except CypherSyntaxError as e:
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raise ValueError(f"Generated Cypher Statement is not valid\n{e}")
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def refresh_schema(self) -> None:
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"""
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Refreshes the Neo4j graph schema information.
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"""
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node_properties = [el["output"] for el in self.query(node_properties_query)]
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rel_properties = [el["output"] for el in self.query(rel_properties_query)]
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relationships = [el["output"] for el in self.query(rel_query)]
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self.structured_schema = {
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"node_props": {el["labels"]: el["properties"] for el in node_properties},
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"rel_props": {el["type"]: el["properties"] for el in rel_properties},
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"relationships": relationships,
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}
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# Format node properties
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formatted_node_props = []
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for el in node_properties:
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props_str = ", ".join(
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[f"{prop['property']}: {prop['type']}" for prop in el["properties"]]
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)
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formatted_node_props.append(f"{el['labels']} {{{props_str}}}")
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# Format relationship properties
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formatted_rel_props = []
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for el in rel_properties:
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props_str = ", ".join(
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[f"{prop['property']}: {prop['type']}" for prop in el["properties"]]
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)
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formatted_rel_props.append(f"{el['type']} {{{props_str}}}")
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# Format relationships
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formatted_rels = [
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f"(:{el['start']})-[:{el['type']}]->(:{el['end']})" for el in relationships
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]
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self.schema = "\n".join(
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[
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"Node properties are the following:",
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",".join(formatted_node_props),
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"Relationship properties are the following:",
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",".join(formatted_rel_props),
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"The relationships are the following:",
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",".join(formatted_rels),
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]
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)
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def add_graph_documents(
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self, graph_documents: List[GraphDocument], include_source: bool = False
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) -> None:
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"""
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Take GraphDocument as input as uses it to construct a graph.
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"""
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for document in graph_documents:
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include_docs_query = (
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"CREATE (d:Document) "
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"SET d.text = $document.page_content "
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"SET d += $document.metadata "
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"WITH d "
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)
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# Import nodes
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self.query(
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(
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f"{include_docs_query if include_source else ''}"
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"UNWIND $data AS row "
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"CALL apoc.merge.node([row.type], {id: row.id}, "
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"row.properties, {}) YIELD node "
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f"{'MERGE (d)-[:MENTIONS]->(node) ' if include_source else ''}"
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"RETURN distinct 'done' AS result"
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),
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{
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"data": [el.__dict__ for el in document.nodes],
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"document": document.source.__dict__,
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},
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)
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# Import relationships
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self.query(
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"UNWIND $data AS row "
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"CALL apoc.merge.node([row.source_label], {id: row.source},"
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"{}, {}) YIELD node as source "
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"CALL apoc.merge.node([row.target_label], {id: row.target},"
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"{}, {}) YIELD node as target "
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"CALL apoc.merge.relationship(source, row.type, "
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"{}, row.properties, target) YIELD rel "
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"RETURN distinct 'done'",
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{
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"data": [
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{
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"source": el.source.id,
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"source_label": el.source.type,
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"target": el.target.id,
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"target_label": el.target.type,
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"type": el.type.replace(" ", "_").upper(),
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"properties": el.properties,
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}
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for el in document.relationships
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]
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},
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)
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