Coverage for python/lsst/dax/apdb/apdbMetadata.py: 100%
15 statements
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« prev ^ index » next coverage.py v7.5.1, created at 2024-05-16 03:20 -0700
1# This file is part of dax_apdb.
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/>.
22from __future__ import annotations
24__all__ = ["ApdbMetadata"]
26from abc import ABC, abstractmethod
27from collections.abc import Generator
30class ApdbMetadata(ABC):
31 """Interface for accessing APDB metadata.
33 Metadata is a collection of key/value items usually stored in a special
34 table in the database. This abstract interface provides methods for
35 accessing and modifying it.
36 """
38 @abstractmethod
39 def get(self, key: str, default: str | None = None) -> str | None:
40 """Retrieve value of a given metadata record.
42 Parameters
43 ----------
44 key : `str`
45 Metadata key, arbitrary non-empty string.
46 default : `str`, optional
47 Default value returned when key does not exist, can be string
48 or `None`.
50 Returns
51 -------
52 value : `str` or `None`
53 Metadata value, if key does not exist then ``default`` is returned.
54 """
55 raise NotImplementedError()
57 @abstractmethod
58 def set(self, key: str, value: str, *, force: bool = False) -> None:
59 """Set value for a given metadata record.
61 Parameters
62 ----------
63 key : `str`
64 Metadata key, arbitrary non-empty string.
65 value : `str`
66 New metadata value, an arbitrary string. Due to deficiencies of
67 some database engines we are not allowing empty strings to be
68 stored in the database, and ``value`` cannot be an empty string.
69 force : `bool`, optional
70 Controls handling of existing metadata. With default `False`
71 value an exception is raised if ``key`` already exists, if `True`
72 is passed then value of the existing key will be updated.
74 Raises
75 ------
76 KeyError
77 Raised if key already exists but ``force`` option is false.
78 ValueError
79 Raised if key or value parameters are empty.
80 """
81 raise NotImplementedError()
83 @abstractmethod
84 def delete(self, key: str) -> bool:
85 """Delete metadata record.
87 Parameters
88 ----------
89 key : `str`
90 Metadata key, arbitrary non-empty string.
92 Returns
93 -------
94 existed : `bool`
95 `True` is returned if attribute existed before it was deleted.
96 """
97 raise NotImplementedError()
99 @abstractmethod
100 def items(self) -> Generator[tuple[str, str], None, None]:
101 """Iterate over records and yield their keys and values.
103 Yields
104 ------
105 key : `str`
106 Metadata key.
107 value : `str`
108 Corresponding metadata value.
109 """
110 raise NotImplementedError()
112 @abstractmethod
113 def empty(self) -> bool:
114 """Check whether attributes set is empty.
116 Returns
117 -------
118 empty : `bool`
119 `True` if there are no any attributes defined. `True` is also
120 returned if metadata table is missing.
121 """
122 raise NotImplementedError()