Coverage for python/lsst/daf/butler/registry/interfaces/_attributes.py : 70%

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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/>.
21from __future__ import annotations
23__all__ = [
24 "ButlerAttributeManager",
25 "ButlerAttributeExistsError",
26]
28from abc import ABC, abstractmethod
29from typing import (
30 Iterable,
31 Optional,
32 Tuple,
33 TYPE_CHECKING,
34)
36if TYPE_CHECKING: 36 ↛ 37line 36 didn't jump to line 37, because the condition on line 36 was never true
37 from ._database import Database, StaticTablesContext
40class ButlerAttributeExistsError(RuntimeError):
41 """Exception raised when trying to update existing attribute without
42 specifying ``force`` option.
43 """
46class ButlerAttributeManager(ABC):
47 """An interface for managing butler attributes in a `Registry`.
49 Attributes are represented in registry as a set of name-value pairs, both
50 have string type. Any non-string data types (e.g. integers) need to be
51 converted to/from strings on client side. Attribute names can be arbitrary
52 strings, no particular structure is enforced by this interface. Attribute
53 names are globally unique, to avoid potential collision clients should
54 follow some common convention for attribute names, e.g. dot-separated
55 components (``config.managers.opaque``).
57 One of the critical pieces of information that will be stored as
58 attribute is the version of database schema which needs to be known
59 before registry can do any operations on database. For that reasons it is
60 likely there will be only one implementation of this interface which uses
61 database table with a stable schema.
62 """
64 @classmethod
65 @abstractmethod
66 def initialize(cls, db: Database, context: StaticTablesContext) -> ButlerAttributeManager:
67 """Construct an instance of the manager.
69 Parameters
70 ----------
71 db : `Database`
72 Interface to the underlying database engine and namespace.
73 context : `StaticTablesContext`
74 Context object obtained from `Database.declareStaticTables`; used
75 to declare any tables that should always be present in a layer
76 implemented with this manager.
78 Returns
79 -------
80 manager : `ButlerAttributeManager`
81 An instance of `ButlerAttributeManager`.
82 """
83 raise NotImplementedError()
85 @abstractmethod
86 def get(self, name: str, default: Optional[str] = None) -> Optional[str]:
87 """Retrieve value of a given attribute.
89 Parameters
90 ----------
91 name : `str`
92 Attribute name, arbitrary non-empty string.
93 default : `str`, optional
94 Default value returned when attribute does not exist, can be
95 string or `None`.
97 Returns
98 -------
99 value : `str`
100 Attribute value, if attribute does not exist then ``default`` is
101 returned.
102 """
103 raise NotImplementedError()
105 @abstractmethod
106 def set(self, name: str, value: str, *, force: bool = False) -> None:
107 """Set value for a given attribute.
109 Parameters
110 ----------
111 name : `str`
112 Attribute name, arbitrary non-empty string.
113 value : `str`
114 New value for an attribute, an arbitrary string. Due to
115 deficiencies of some database engines we are not allowing empty
116 strings to be stored in the database, and ``value`` cannot be an
117 empty string.
118 force : `bool`, optional
119 Controls handling of existing attributes. With default `False`
120 value an exception is raised if attribute ``name`` already exists,
121 if `True` is passed then value of the existing attribute will be
122 updated.
124 Raises
125 ------
126 ButlerAttributeExistsError
127 Raised if attribute already exists but ``force`` option is false.
128 ValueError
129 Raised if name or value parameters are empty.
130 """
131 raise NotImplementedError()
133 @abstractmethod
134 def delete(self, name: str) -> bool:
135 """Delete an attribute.
137 Parameters
138 ----------
139 name : `str`
140 Attribute name, arbitrary non-empty string.
142 Returns
143 -------
144 existed : `bool`
145 `True` is returned if attribute existed before it was deleted.
146 """
147 raise NotImplementedError()
149 @abstractmethod
150 def items(self) -> Iterable[Tuple[str, str]]:
151 """Iterate over attributes and yield their names and values.
153 Yields
154 ------
155 name : `str`
156 Attribute name.
157 value : `str`
158 Corresponding attribute value.
159 """
160 raise NotImplementedError()