Coverage for python/lsst/daf/butler/formatters/packages.py: 62%
35 statements
« prev ^ index » next coverage.py v6.4.2, created at 2022-08-04 02:20 -0700
« prev ^ index » next coverage.py v6.4.2, created at 2022-08-04 02:20 -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/>.
22__all__ = ("PackagesFormatter",)
24import os.path
25from typing import Any, Optional, Type
27from lsst.daf.butler.formatters.file import FileFormatter
28from lsst.utils.packages import Packages
31class PackagesFormatter(FileFormatter):
32 """Interface for reading and writing `~lsst.utils.packages.Packages`.
34 This formatter supports write parameters:
36 * ``format``: The file format to use to write the package data. Allowed
37 options are ``yaml``, ``json``, and ``pickle``.
38 """
40 supportedWriteParameters = frozenset({"format"})
41 supportedExtensions = frozenset({".yaml", ".pickle", ".pkl", ".json"})
43 # MyPy does't like the fact that the base declares this an instance
44 # attribute while this derived class uses a property.
45 @property
46 def extension(self) -> str: # type: ignore
47 # Default to YAML but allow configuration via write parameter
48 format = self.writeParameters.get("format", "yaml")
49 ext = "." + format
50 if ext not in self.supportedExtensions: 50 ↛ 51line 50 didn't jump to line 51, because the condition on line 50 was never true
51 raise RuntimeError(f"Requested file format '{format}' is not supported for Packages")
52 return ext
54 def _readFile(self, path: str, pytype: Optional[Type] = None) -> Any:
55 """Read a file from the path.
57 Parameters
58 ----------
59 path : `str`
60 Path to use to open the file.
61 pytype : `type`
62 Class to use to read the serialized file.
64 Returns
65 -------
66 data : `object`
67 Instance of class ``pytype`` read from serialized file. None
68 if the file could not be opened.
69 """
70 if not os.path.exists(path):
71 return None
73 assert pytype is not None
74 assert issubclass(pytype, Packages)
75 return pytype.read(path)
77 def _fromBytes(self, serializedDataset: Any, pytype: Optional[Type] = None) -> Any:
78 """Read the bytes object as a python object.
80 Parameters
81 ----------
82 serializedDataset : `bytes`
83 Bytes object to unserialize.
84 pytype : `type`
85 The Python type to be instantiated. Required.
87 Returns
88 -------
89 inMemoryDataset : `object`
90 The requested data as an object, or None if the string could
91 not be read.
92 """
93 # The format can not come from the formatter configuration
94 # because the current configuration has no connection to how
95 # the data were stored.
96 if serializedDataset.startswith(b"!<lsst."): 96 ↛ 98line 96 didn't jump to line 98, because the condition on line 96 was never false
97 format = "yaml"
98 elif serializedDataset.startswith(b'{"'):
99 format = "json"
100 else:
101 format = "pickle"
103 assert pytype is not None
104 assert issubclass(pytype, Packages)
105 return pytype.fromBytes(serializedDataset, format)
107 def _writeFile(self, inMemoryDataset: Any) -> None:
108 """Write the in memory dataset to file on disk.
110 Parameters
111 ----------
112 inMemoryDataset : `object`
113 Object to serialize.
115 Raises
116 ------
117 Exception
118 The file could not be written.
119 """
120 inMemoryDataset.write(self.fileDescriptor.location.path)
122 def _toBytes(self, inMemoryDataset: Any) -> bytes:
123 """Write the in memory dataset to a bytestring.
125 Parameters
126 ----------
127 inMemoryDataset : `object`
128 Object to serialize
130 Returns
131 -------
132 serializedDataset : `bytes`
133 YAML string encoded to bytes.
135 Raises
136 ------
137 Exception
138 The object could not be serialized.
139 """
140 format = self.extension.lstrip(".")
141 return inMemoryDataset.toBytes(format)