Coverage for python/lsst/daf/butler/formatters/yaml.py: 30%
43 statements
« prev ^ index » next coverage.py v6.5.0, created at 2023-01-26 02:04 -0800
« prev ^ index » next coverage.py v6.5.0, created at 2023-01-26 02:04 -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/>.
22from __future__ import annotations
24__all__ = ("YamlFormatter",)
26import dataclasses
27from typing import Any, Optional, Type
29import yaml
31from .file import FileFormatter
34class YamlFormatter(FileFormatter):
35 """Formatter implementation for YAML files."""
37 extension = ".yaml"
39 unsupportedParameters = None
40 """This formatter does not support any parameters"""
42 supportedWriteParameters = frozenset({"unsafe_dump"})
43 """Allow the normal yaml.dump to be used to write the YAML. Use this
44 if you know that your class has registered representers."""
46 def _readFile(self, path: str, pytype: Type[Any] | None = None) -> Any:
47 """Read a file from the path in YAML format.
49 Parameters
50 ----------
51 path : `str`
52 Path to use to open YAML format file.
53 pytype : `class`, optional
54 Not used by this implementation.
56 Returns
57 -------
58 data : `object`
59 Either data as Python object read from YAML file, or None
60 if the file could not be opened.
62 Notes
63 -----
64 The `~yaml.SafeLoader` is used when parsing the YAML file.
65 """
66 try:
67 with open(path, "rb") as fd:
68 data = self._fromBytes(fd.read(), pytype)
69 except FileNotFoundError:
70 data = None
72 return data
74 def _fromBytes(self, serializedDataset: bytes, pytype: Optional[Type[Any]] = None) -> Any:
75 """Read the bytes object as a python object.
77 Parameters
78 ----------
79 serializedDataset : `bytes`
80 Bytes object to unserialize.
81 pytype : `class`, optional
82 Not used by this implementation.
84 Returns
85 -------
86 inMemoryDataset : `object`
87 The requested data as an object, or None if the string could
88 not be read.
90 Notes
91 -----
92 The `~yaml.SafeLoader` is used when parsing the YAML.
93 """
94 data = yaml.safe_load(serializedDataset)
96 try:
97 data = data.exportAsDict()
98 except AttributeError:
99 pass
100 return data
102 def _writeFile(self, inMemoryDataset: Any) -> None:
103 """Write the in memory dataset to file on disk.
105 Will look for `_asdict()` method to aid YAML serialization, following
106 the approach of the simplejson module. The `dict` will be passed
107 to the relevant constructor on read.
109 Parameters
110 ----------
111 inMemoryDataset : `object`
112 Object to serialize.
114 Raises
115 ------
116 Exception
117 The file could not be written.
119 Notes
120 -----
121 The `~yaml.SafeDumper` is used when generating the YAML serialization.
122 This will fail for data structures that have complex python classes
123 without a registered YAML representer.
124 """
125 self.fileDescriptor.location.uri.write(self._toBytes(inMemoryDataset))
127 def _toBytes(self, inMemoryDataset: Any) -> bytes:
128 """Write the in memory dataset to a bytestring.
130 Will look for `_asdict()` method to aid YAML serialization, following
131 the approach of the simplejson module. The `dict` will be passed
132 to the relevant constructor on read.
134 Parameters
135 ----------
136 inMemoryDataset : `object`
137 Object to serialize
139 Returns
140 -------
141 serializedDataset : `bytes`
142 YAML string encoded to bytes.
144 Raises
145 ------
146 Exception
147 The object could not be serialized.
149 Notes
150 -----
151 The `~yaml.SafeDumper` is used when generating the YAML serialization.
152 This will fail for data structures that have complex python classes
153 without a registered YAML representer.
154 """
155 if hasattr(inMemoryDataset, "dict") and hasattr(inMemoryDataset, "json"):
156 # Pydantic-like model if both dict() and json() exist.
157 try:
158 inMemoryDataset = inMemoryDataset.dict()
159 except Exception:
160 pass
162 if dataclasses.is_dataclass(inMemoryDataset):
163 inMemoryDataset = dataclasses.asdict(inMemoryDataset)
164 elif hasattr(inMemoryDataset, "_asdict"):
165 inMemoryDataset = inMemoryDataset._asdict()
166 unsafe_dump = self.writeParameters.get("unsafe_dump", False)
167 if unsafe_dump:
168 serialized = yaml.dump(inMemoryDataset)
169 else:
170 serialized = yaml.safe_dump(inMemoryDataset)
171 return serialized.encode()