Coverage for python/lsst/daf/butler/formatters/yaml.py: 25%

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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 software is dual licensed under the GNU General Public License and also 

10# under a 3-clause BSD license. Recipients may choose which of these licenses 

11# to use; please see the files gpl-3.0.txt and/or bsd_license.txt, 

12# respectively. If you choose the GPL option then the following text applies 

13# (but note that there is still no warranty even if you opt for BSD instead): 

14# 

15# This program is free software: you can redistribute it and/or modify 

16# it under the terms of the GNU General Public License as published by 

17# the Free Software Foundation, either version 3 of the License, or 

18# (at your option) any later version. 

19# 

20# This program is distributed in the hope that it will be useful, 

21# but WITHOUT ANY WARRANTY; without even the implied warranty of 

22# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 

23# GNU General Public License for more details. 

24# 

25# You should have received a copy of the GNU General Public License 

26# along with this program. If not, see <http://www.gnu.org/licenses/>. 

27 

28from __future__ import annotations 

29 

30__all__ = ("YamlFormatter",) 

31 

32import contextlib 

33import dataclasses 

34from typing import Any 

35 

36import yaml 

37 

38from .file import FileFormatter 

39 

40 

41class YamlFormatter(FileFormatter): 

42 """Formatter implementation for YAML files.""" 

43 

44 extension = ".yaml" 

45 

46 unsupportedParameters = None 

47 """This formatter does not support any parameters""" 

48 

49 supportedWriteParameters = frozenset({"unsafe_dump"}) 

50 """Allow the normal yaml.dump to be used to write the YAML. Use this 

51 if you know that your class has registered representers.""" 

52 

53 def _readFile(self, path: str, pytype: type[Any] | None = None) -> Any: 

54 """Read a file from the path in YAML format. 

55 

56 Parameters 

57 ---------- 

58 path : `str` 

59 Path to use to open YAML format file. 

60 pytype : `class`, optional 

61 Not used by this implementation. 

62 

63 Returns 

64 ------- 

65 data : `object` 

66 Either data as Python object read from YAML file, or None 

67 if the file could not be opened. 

68 

69 Notes 

70 ----- 

71 The `~yaml.SafeLoader` is used when parsing the YAML file. 

72 """ 

73 try: 

74 with open(path, "rb") as fd: 

75 data = self._fromBytes(fd.read(), pytype) 

76 except FileNotFoundError: 

77 data = None 

78 

79 return data 

80 

81 def _fromBytes(self, serializedDataset: bytes, pytype: type[Any] | None = None) -> Any: 

82 """Read the bytes object as a python object. 

83 

84 Parameters 

85 ---------- 

86 serializedDataset : `bytes` 

87 Bytes object to unserialize. 

88 pytype : `class`, optional 

89 Not used by this implementation. 

90 

91 Returns 

92 ------- 

93 inMemoryDataset : `object` 

94 The requested data as an object, or None if the string could 

95 not be read. 

96 

97 Notes 

98 ----- 

99 The `~yaml.SafeLoader` is used when parsing the YAML. 

100 """ 

101 data = yaml.safe_load(serializedDataset) 

102 

103 with contextlib.suppress(AttributeError): 

104 data = data.exportAsDict() 

105 

106 return data 

107 

108 def _writeFile(self, inMemoryDataset: Any) -> None: 

109 """Write the in memory dataset to file on disk. 

110 

111 Will look for `_asdict()` method to aid YAML serialization, following 

112 the approach of the simplejson module. The `dict` will be passed 

113 to the relevant constructor on read. 

114 

115 Parameters 

116 ---------- 

117 inMemoryDataset : `object` 

118 Object to serialize. 

119 

120 Raises 

121 ------ 

122 Exception 

123 The file could not be written. 

124 

125 Notes 

126 ----- 

127 The `~yaml.SafeDumper` is used when generating the YAML serialization. 

128 This will fail for data structures that have complex python classes 

129 without a registered YAML representer. 

130 """ 

131 self.fileDescriptor.location.uri.write(self._toBytes(inMemoryDataset)) 

132 

133 def _toBytes(self, inMemoryDataset: Any) -> bytes: 

134 """Write the in memory dataset to a bytestring. 

135 

136 Will look for `_asdict()` method to aid YAML serialization, following 

137 the approach of the simplejson module. The `dict` will be passed 

138 to the relevant constructor on read. 

139 

140 Parameters 

141 ---------- 

142 inMemoryDataset : `object` 

143 Object to serialize 

144 

145 Returns 

146 ------- 

147 serializedDataset : `bytes` 

148 YAML string encoded to bytes. 

149 

150 Raises 

151 ------ 

152 Exception 

153 The object could not be serialized. 

154 

155 Notes 

156 ----- 

157 The `~yaml.SafeDumper` is used when generating the YAML serialization. 

158 This will fail for data structures that have complex python classes 

159 without a registered YAML representer. 

160 """ 

161 converted = False 

162 if hasattr(inMemoryDataset, "model_dump") and hasattr(inMemoryDataset, "model_dump_json"): 

163 # Pydantic v2-like model if both model_dump() and model_json() 

164 # exist. 

165 with contextlib.suppress(Exception): 

166 inMemoryDataset = inMemoryDataset.model_dump() 

167 converted = True 

168 

169 if not converted and hasattr(inMemoryDataset, "dict") and hasattr(inMemoryDataset, "json"): 

170 # Pydantic v1-like model if both dict() and json() exist. 

171 with contextlib.suppress(Exception): 

172 inMemoryDataset = inMemoryDataset.dict() 

173 converted = True 

174 

175 if not converted: 

176 if dataclasses.is_dataclass(inMemoryDataset): 

177 inMemoryDataset = dataclasses.asdict(inMemoryDataset) 

178 elif hasattr(inMemoryDataset, "_asdict"): 

179 inMemoryDataset = inMemoryDataset._asdict() 

180 

181 unsafe_dump = self.writeParameters.get("unsafe_dump", False) 

182 if unsafe_dump: 

183 serialized = yaml.dump(inMemoryDataset) 

184 else: 

185 serialized = yaml.safe_dump(inMemoryDataset) 

186 return serialized.encode()