Coverage for python/lsst/daf/butler/registry/interfaces/_attributes.py: 95%
22 statements
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« prev ^ index » next coverage.py v6.5.0, created at 2023-04-13 02:34 -0700
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 abstractmethod
29from typing import TYPE_CHECKING, Iterable, Optional, Tuple
31from ._versioning import VersionedExtension, VersionTuple
33if TYPE_CHECKING:
34 from ._database import Database, StaticTablesContext
37class ButlerAttributeExistsError(RuntimeError):
38 """Exception raised when trying to update existing attribute without
39 specifying ``force`` option.
40 """
43class ButlerAttributeManager(VersionedExtension):
44 """An interface for managing butler attributes in a `Registry`.
46 Attributes are represented in registry as a set of name-value pairs, both
47 have string type. Any non-string data types (e.g. integers) need to be
48 converted to/from strings on client side. Attribute names can be arbitrary
49 strings, no particular structure is enforced by this interface. Attribute
50 names are globally unique, to avoid potential collision clients should
51 follow some common convention for attribute names, e.g. dot-separated
52 components (``config.managers.opaque``).
54 One of the critical pieces of information that will be stored as
55 attribute is the version of database schema which needs to be known
56 before registry can do any operations on database. For that reasons it is
57 likely there will be only one implementation of this interface which uses
58 database table with a stable schema.
59 """
61 def __init__(self, *, registry_schema_version: VersionTuple | None = None) -> None:
62 super().__init__(registry_schema_version=registry_schema_version)
64 @classmethod
65 @abstractmethod
66 def initialize(
67 cls, db: Database, context: StaticTablesContext, registry_schema_version: VersionTuple | None = None
68 ) -> ButlerAttributeManager:
69 """Construct an instance of the manager.
71 Parameters
72 ----------
73 db : `Database`
74 Interface to the underlying database engine and namespace.
75 context : `StaticTablesContext`
76 Context object obtained from `Database.declareStaticTables`; used
77 to declare any tables that should always be present in a layer
78 implemented with this manager.
79 registry_schema_version : `VersionTuple` or `None`
80 Schema version of this extension as defined in registry.
82 Returns
83 -------
84 manager : `ButlerAttributeManager`
85 An instance of `ButlerAttributeManager`.
86 """
87 raise NotImplementedError()
89 @abstractmethod
90 def get(self, name: str, default: Optional[str] = None) -> Optional[str]:
91 """Retrieve value of a given attribute.
93 Parameters
94 ----------
95 name : `str`
96 Attribute name, arbitrary non-empty string.
97 default : `str`, optional
98 Default value returned when attribute does not exist, can be
99 string or `None`.
101 Returns
102 -------
103 value : `str`
104 Attribute value, if attribute does not exist then ``default`` is
105 returned.
106 """
107 raise NotImplementedError()
109 @abstractmethod
110 def set(self, name: str, value: str, *, force: bool = False) -> None:
111 """Set value for a given attribute.
113 Parameters
114 ----------
115 name : `str`
116 Attribute name, arbitrary non-empty string.
117 value : `str`
118 New value for an attribute, an arbitrary string. Due to
119 deficiencies of some database engines we are not allowing empty
120 strings to be stored in the database, and ``value`` cannot be an
121 empty string.
122 force : `bool`, optional
123 Controls handling of existing attributes. With default `False`
124 value an exception is raised if attribute ``name`` already exists,
125 if `True` is passed then value of the existing attribute will be
126 updated.
128 Raises
129 ------
130 ButlerAttributeExistsError
131 Raised if attribute already exists but ``force`` option is false.
132 ValueError
133 Raised if name or value parameters are empty.
134 """
135 raise NotImplementedError()
137 @abstractmethod
138 def delete(self, name: str) -> bool:
139 """Delete an attribute.
141 Parameters
142 ----------
143 name : `str`
144 Attribute name, arbitrary non-empty string.
146 Returns
147 -------
148 existed : `bool`
149 `True` is returned if attribute existed before it was deleted.
150 """
151 raise NotImplementedError()
153 @abstractmethod
154 def items(self) -> Iterable[Tuple[str, str]]:
155 """Iterate over attributes and yield their names and values.
157 Yields
158 ------
159 name : `str`
160 Attribute name.
161 value : `str`
162 Corresponding attribute value.
163 """
164 raise NotImplementedError()
166 @abstractmethod
167 def empty(self) -> bool:
168 """Check whether attributes set is empty.
170 Returns
171 -------
172 empty : `bool`
173 True if there are no any attributes defined.
174 """
175 raise NotImplementedError()