Coverage for python/lsst/daf/butler/_deferredDatasetHandle.py: 49%
33 statements
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« prev ^ index » next coverage.py v6.5.0, created at 2023-01-10 02:33 -0800
1# This file is part of daf_butler.
2#
3# Developed for the LSST Data Management System.
4# This product includes software developed by the LSST Project
5# (http://www.lsst.org).
6# See the COPYRIGHT file at the top-level directory of this distribution
7# for details of code ownership.
8#
9# This program is free software: you can redistribute it and/or modify
10# it under the terms of the GNU General Public License as published by
11# the Free Software Foundation, either version 3 of the License, or
12# (at your option) any later version.
13#
14# This program is distributed in the hope that it will be useful,
15# but WITHOUT ANY WARRANTY; without even the implied warranty of
16# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17# GNU General Public License for more details.
18#
19# You should have received a copy of the GNU General Public License
20# along with this program. If not, see <http://www.gnu.org/licenses/>.
22"""
23Module containing classes used with deferring dataset loading
24"""
25from __future__ import annotations
27__all__ = ("DeferredDatasetHandle",)
29import dataclasses
30from typing import TYPE_CHECKING, Any, Optional, Union
32if TYPE_CHECKING: 32 ↛ 33line 32 didn't jump to line 33, because the condition on line 32 was never true
33 from ._limited_butler import LimitedButler
34 from .core import DataCoordinate, DatasetRef, StorageClass
37@dataclasses.dataclass(frozen=True)
38class DeferredDatasetHandle:
39 """Proxy class that provides deferred loading of datasets from a butler."""
41 def get(
42 self,
43 *,
44 component: Optional[str] = None,
45 parameters: Optional[dict] = None,
46 storageClass: str | StorageClass | None = None,
47 **kwargs: dict,
48 ) -> Any:
49 """Retrieves the dataset pointed to by this handle
51 This handle may be used multiple times, possibly with different
52 parameters.
54 Parameters
55 ----------
56 component : `str` or None
57 If the deferred object is a component dataset type, this parameter
58 may specify the name of the component to use in the get operation.
59 parameters : `dict` or None
60 The parameters argument will be passed to the butler get method.
61 It defaults to None. If the value is not None, this dict will
62 be merged with the parameters dict used to construct the
63 `DeferredDatasetHandle` class.
64 storageClass : `StorageClass` or `str`, optional
65 The storage class to be used to override the Python type
66 returned by this method. By default the returned type matches
67 the dataset type definition for this dataset or the storage
68 class specified when this object was created. Specifying a
69 read `StorageClass` can force a different type to be returned.
70 This type must be compatible with the original type.
71 **kwargs
72 This argument is deprecated and only exists to support legacy
73 gen2 butler code during migration. It is completely ignored
74 and will be removed in the future.
76 Returns
77 -------
78 return : `Object`
79 The dataset pointed to by this handle
80 """
81 if self.parameters is not None:
82 mergedParameters = self.parameters.copy()
83 if parameters is not None:
84 mergedParameters.update(parameters)
85 elif parameters is not None:
86 mergedParameters = parameters
87 else:
88 mergedParameters = {}
89 if storageClass is None:
90 storageClass = self.storageClass
92 ref = self.ref.makeComponentRef(component) if component is not None else self.ref
93 return self.butler.getDirect(ref, parameters=mergedParameters, storageClass=storageClass)
95 @property
96 def dataId(self) -> DataCoordinate:
97 """The full data ID associated with the dataset
98 (`DataCoordinate`).
100 Guaranteed to contain records.
101 """
102 return self.ref.dataId
104 butler: LimitedButler
105 """The butler that will be used to fetch the dataset (`LimitedButler`).
106 """
108 ref: DatasetRef
109 """Reference to the dataset (`DatasetRef`).
110 """
112 parameters: Optional[dict]
113 """Optional parameters that may be used to specify a subset of the dataset
114 to be loaded (`dict` or `None`).
115 """
117 storageClass: Optional[Union[str, StorageClass]] = None
118 """Optional storage class override that can be applied on ``get()``."""