Coverage for python/lsst/obs/base/formatters/packages.py: 62%
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1# This file is part of obs_base.
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
26from lsst.daf.butler.formatters.file import FileFormatter
29class PackagesFormatter(FileFormatter):
30 """Interface for reading and writing `~lsst.utils.packages.Packages`.
32 This formatter supports write parameters:
34 * ``format``: The file format to use to write the package data. Allowed
35 options are ``yaml``, ``json``, and ``pickle``.
36 """
38 supportedWriteParameters = frozenset({"format"})
39 supportedExtensions = frozenset({".yaml", ".pickle", ".pkl", ".json"})
41 # MyPy does't like the fact that the base declares this an instance
42 # attribute while this derived class uses a property.
43 @property
44 def extension(self) -> str: # type: ignore
45 # Default to YAML but allow configuration via write parameter
46 format = self.writeParameters.get("format", "yaml")
47 ext = "." + format
48 if ext not in self.supportedExtensions: 48 ↛ 49line 48 didn't jump to line 49, because the condition on line 48 was never true
49 raise RuntimeError(f"Requested file format '{format}' is not supported for Packages")
50 return ext
52 def _readFile(self, path, pytype):
53 """Read a file from the path in FITS format.
55 Parameters
56 ----------
57 path : `str`
58 Path to use to open the file.
59 pytype : `type`
60 Class to use to read the serialized file.
62 Returns
63 -------
64 data : `object`
65 Instance of class ``pytype`` read from serialized file. None
66 if the file could not be opened.
67 """
68 if not os.path.exists(path):
69 return None
71 return pytype.read(path)
73 def _fromBytes(self, serializedDataset, pytype=None):
74 """Read the bytes object as a python object.
76 Parameters
77 ----------
78 serializedDataset : `bytes`
79 Bytes object to unserialize.
80 pytype : `type`
81 The Python type to be instantiated. Required.
83 Returns
84 -------
85 inMemoryDataset : `object`
86 The requested data as an object, or None if the string could
87 not be read.
88 """
89 # The format can not come from the formatter configuration
90 # because the current configuration has no connection to how
91 # the data were stored.
92 if serializedDataset.startswith(b"!<lsst."): 92 ↛ 94line 92 didn't jump to line 94, because the condition on line 92 was never false
93 format = "yaml"
94 elif serializedDataset.startswith(b'{"'):
95 format = "json"
96 else:
97 format = "pickle"
98 return pytype.fromBytes(serializedDataset, format)
100 def _writeFile(self, inMemoryDataset):
101 """Write the in memory dataset to file on disk.
103 Parameters
104 ----------
105 inMemoryDataset : `object`
106 Object to serialize.
108 Raises
109 ------
110 Exception
111 The file could not be written.
112 """
113 inMemoryDataset.write(self.fileDescriptor.location.path)
115 def _toBytes(self, inMemoryDataset):
116 """Write the in memory dataset to a bytestring.
118 Parameters
119 ----------
120 inMemoryDataset : `object`
121 Object to serialize
123 Returns
124 -------
125 serializedDataset : `bytes`
126 YAML string encoded to bytes.
128 Raises
129 ------
130 Exception
131 The object could not be serialized.
132 """
133 format = self.extension.lstrip(".")
134 return inMemoryDataset.toBytes(format)