Source code for arango.cursor

__all__ = ["Cursor"]

from collections import deque
from typing import Any, Deque, Optional, Sequence

from arango.connection import BaseConnection
from arango.exceptions import (
    CursorCloseError,
    CursorCountError,
    CursorEmptyError,
    CursorNextError,
    CursorStateError,
)
from arango.request import Request
from arango.typings import Json


[docs]class Cursor: """Cursor API wrapper. Cursors fetch query results from ArangoDB server in batches. Cursor objects are *stateful* as they store the fetched items in-memory. They must not be shared across threads without proper locking mechanism. :param connection: HTTP connection. :param init_data: Cursor initialization data. :type init_data: dict :param cursor_type: Cursor type ("cursor" or "export"). :type cursor_type: str """ __slots__ = [ "_conn", "_type", "_id", "_count", "_cached", "_stats", "_profile", "_warnings", "_has_more", "_batch", ] def __init__( self, connection: BaseConnection, init_data: Json, cursor_type: str = "cursor", ) -> None: self._conn = connection self._type = cursor_type self._batch: Deque[Any] = deque() self._id = None self._count: Optional[int] = None self._cached = None self._stats = None self._profile = None self._warnings = None self._update(init_data) def __iter__(self) -> "Cursor": return self def __next__(self) -> Any: # pragma: no cover return self.next() def __enter__(self) -> "Cursor": return self def __len__(self) -> int: if self._count is None: raise CursorCountError("cursor count not enabled") return self._count def __exit__(self, *_: Any) -> None: self.close(ignore_missing=True) def __repr__(self) -> str: return f"<Cursor {self._id}>" if self._id else "<Cursor>" def _update(self, data: Json) -> Json: """Update the cursor using data from ArangoDB server. :param data: Cursor data from ArangoDB server (e.g. results). :type data: dict :return: Update cursor data. :rtype: dict """ result: Json = {} if "id" in data: self._id = data["id"] result["id"] = data["id"] if "count" in data: self._count = data["count"] result["count"] = data["count"] if "cached" in data: self._cached = data["cached"] result["cached"] = data["cached"] self._has_more = bool(data["hasMore"]) result["has_more"] = data["hasMore"] self._batch.extend(data["result"]) result["batch"] = data["result"] if "extra" in data: extra = data["extra"] if "profile" in extra: self._profile = extra["profile"] result["profile"] = extra["profile"] if "warnings" in extra: self._warnings = extra["warnings"] result["warnings"] = extra["warnings"] if "stats" in extra: stats = extra["stats"] if "writesExecuted" in stats: stats["modified"] = stats.pop("writesExecuted") if "writesIgnored" in stats: stats["ignored"] = stats.pop("writesIgnored") if "scannedFull" in stats: stats["scanned_full"] = stats.pop("scannedFull") if "scannedIndex" in stats: stats["scanned_index"] = stats.pop("scannedIndex") if "executionTime" in stats: stats["execution_time"] = stats.pop("executionTime") if "httpRequests" in stats: stats["http_requests"] = stats.pop("httpRequests") self._stats = stats result["statistics"] = stats return result @property def id(self) -> Optional[str]: """Return the cursor ID. :return: Cursor ID. :rtype: str """ return self._id @property def type(self) -> str: """Return the cursor type. :return: Cursor type ("cursor" or "export"). :rtype: str """ return self._type
[docs] def batch(self) -> Optional[Deque[Any]]: """Return the current batch of results. :return: Current batch. :rtype: collections.deque """ return self._batch
[docs] def has_more(self) -> Optional[bool]: """Return True if more results are available on the server. :return: True if more results are available on the server. :rtype: bool """ return self._has_more
[docs] def count(self) -> Optional[int]: """Return the total number of documents in the entire result set. :return: Total number of documents, or None if the count option was not enabled during cursor initialization. :rtype: int | None """ return self._count
[docs] def cached(self) -> Optional[bool]: """Return True if results are cached. :return: True if results are cached. :rtype: bool """ return self._cached
[docs] def statistics(self) -> Optional[Json]: """Return cursor statistics. :return: Cursor statistics. :rtype: dict """ return self._stats
[docs] def profile(self) -> Optional[Json]: """Return cursor performance profile. :return: Cursor performance profile. :rtype: dict """ return self._profile
[docs] def warnings(self) -> Optional[Sequence[Json]]: """Return any warnings from the query execution. :return: Warnings, or None if there are none. :rtype: [str] """ return self._warnings
[docs] def empty(self) -> bool: """Check if the current batch is empty. :return: True if current batch is empty, False otherwise. :rtype: bool """ return len(self._batch) == 0
[docs] def next(self) -> Any: """Pop the next item from the current batch. If current batch is empty/depleted, an API request is automatically sent to ArangoDB server to fetch the next batch and update the cursor. :return: Next item in current batch. :raise StopIteration: If the result set is depleted. :raise arango.exceptions.CursorNextError: If batch retrieval fails. :raise arango.exceptions.CursorStateError: If cursor ID is not set. """ if self.empty(): if not self.has_more(): raise StopIteration self.fetch() return self.pop()
[docs] def pop(self) -> Any: """Pop the next item from current batch. If current batch is empty/depleted, an exception is raised. You must call :func:`arango.cursor.Cursor.fetch` to manually fetch the next batch from server. :return: Next item in current batch. :raise arango.exceptions.CursorEmptyError: If current batch is empty. """ if len(self._batch) == 0: raise CursorEmptyError("current batch is empty") return self._batch.popleft()
[docs] def fetch(self) -> Json: """Fetch the next batch from server and update the cursor. :return: New batch details. :rtype: dict :raise arango.exceptions.CursorNextError: If batch retrieval fails. :raise arango.exceptions.CursorStateError: If cursor ID is not set. """ if self._id is None: raise CursorStateError("cursor ID not set") request = Request(method="put", endpoint=f"/_api/{self._type}/{self._id}") resp = self._conn.send_request(request) if not resp.is_success: raise CursorNextError(resp, request) return self._update(resp.body)
[docs] def close(self, ignore_missing: bool = False) -> Optional[bool]: """Close the cursor and free any server resources tied to it. :param ignore_missing: Do not raise exception on missing cursors. :type ignore_missing: bool :return: True if cursor was closed successfully, False if cursor was missing on the server and **ignore_missing** was set to True, None if there are no cursors to close server-side (e.g. result set is smaller than the batch size). :rtype: bool | None :raise arango.exceptions.CursorCloseError: If operation fails. :raise arango.exceptions.CursorStateError: If cursor ID is not set. """ if self._id is None: return None request = Request(method="delete", endpoint=f"/_api/{self._type}/{self._id}") resp = self._conn.send_request(request) if resp.is_success: return True if resp.status_code == 404 and ignore_missing: return False raise CursorCloseError(resp, request)