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- # Copyright (c) "Neo4j"
- # Neo4j Sweden AB [https://neo4j.com]
- #
- # Licensed under the Apache License, Version 2.0 (the "License");
- # you may not use this file except in compliance with the License.
- # You may obtain a copy of the License at
- #
- # https://www.apache.org/licenses/LICENSE-2.0
- #
- # Unless required by applicable law or agreed to in writing, software
- # distributed under the License is distributed on an "AS IS" BASIS,
- # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- # See the License for the specific language governing permissions and
- # limitations under the License.
- from __future__ import annotations
- import typing as t
- if t.TYPE_CHECKING:
- import typing_extensions as te
- _T = t.TypeVar("_T")
- class Query:
- """
- A query with attached extra data.
- This wrapper class for queries is used to attach extra data to queries
- passed to :meth:`.Session.run`/:meth:`.AsyncSession.run` and
- :meth:`.Driver.execute_query`/:meth:`.AsyncDriver.execute_query`,
- fulfilling a similar role as :func:`.unit_of_work` for transactions
- functions.
- :param text: The query text.
- :type text: typing.LiteralString
- :param metadata:
- a dictionary with metadata.
- Specified metadata will be attached to the executing transaction
- and visible in the output of ``SHOW TRANSACTIONS YIELD *``
- It will also get logged to the ``query.log``.
- This functionality makes it easier to tag transactions and is
- equivalent to the ``dbms.setTXMetaData`` procedure, see
- https://neo4j.com/docs/cypher-manual/current/clauses/transaction-clauses/#query-listing-transactions
- and https://neo4j.com/docs/operations-manual/current/reference/procedures/
- for reference.
- :type metadata: typing.Dict[str, typing.Any] | None
- :param timeout:
- the transaction timeout in seconds.
- Transactions that execute longer than the configured timeout will
- be terminated by the database.
- This functionality allows user code to limit query/transaction
- execution time.
- The specified timeout overrides the default timeout configured in
- the database using the ``db.transaction.timeout`` setting
- (``dbms.transaction.timeout`` before Neo4j 5.0).
- Values higher than ``db.transaction.timeout`` will be ignored and
- will fall back to the default for server versions between 4.2 and
- 5.2 (inclusive).
- The value should not represent a negative duration.
- A ``0`` duration will make the transaction execute indefinitely.
- :data:`None` will use the default timeout configured on the server.
- :type timeout: float | None
- """
- def __init__(
- self,
- text: te.LiteralString,
- metadata: dict[str, t.Any] | None = None,
- timeout: float | None = None,
- ) -> None:
- self.text = text
- self.metadata = metadata
- self.timeout = timeout
- def __str__(self) -> te.LiteralString:
- # we know that if Query is constructed with a LiteralString,
- # str(self.text) will be a LiteralString as well. The conversion isn't
- # necessary if the user adheres to the type hints. However, it was
- # here before, and we don't want to break backwards compatibility.
- text: te.LiteralString = str(self.text) # type: ignore[assignment]
- return text
- def unit_of_work(
- metadata: dict[str, t.Any] | None = None,
- timeout: float | None = None,
- ) -> t.Callable[[_T], _T]:
- """
- Configure a transaction function.
- This function is a decorator for transaction functions that allows extra
- control over how the transaction is carried out.
- For example, a timeout may be applied::
- from neo4j import unit_of_work
- @unit_of_work(timeout=100)
- def count_people_tx(tx):
- result = tx.run("MATCH (a:Person) RETURN count(a) AS persons")
- record = result.single()
- return record["persons"]
- :param metadata:
- a dictionary with metadata.
- Specified metadata will be attached to the executing transaction
- and visible in the output of ``SHOW TRANSACTIONS YIELD *``
- It will also get logged to the ``query.log``.
- This functionality makes it easier to tag transactions and is
- equivalent to the ``dbms.setTXMetaData`` procedure, see
- https://neo4j.com/docs/cypher-manual/current/clauses/transaction-clauses/#query-listing-transactions
- and https://neo4j.com/docs/operations-manual/current/reference/procedures/
- for reference.
- :type metadata: typing.Dict[str, typing.Any] | None
- :param timeout:
- the transaction timeout in seconds.
- Transactions that execute longer than the configured timeout will
- be terminated by the database.
- This functionality allows user code to limit query/transaction
- execution time.
- The specified timeout overrides the default timeout configured in
- the database using the ``db.transaction.timeout`` setting
- (``dbms.transaction.timeout`` before Neo4j 5.0).
- Values higher than ``db.transaction.timeout`` will be ignored and
- will fall back to the default for server versions between 4.2 and
- 5.2 (inclusive).
- The value should not represent a negative duration.
- A ``0`` duration will make the transaction execute indefinitely.
- :data:`None` will use the default timeout configured on the server.
- :type timeout: float | None
- :rtype: typing.Callable[[T], T]
- """
- def wrapper(f):
- def wrapped(*args, **kwargs):
- return f(*args, **kwargs)
- wrapped.metadata = metadata
- wrapped.timeout = timeout
- return wrapped
- return wrapper
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