Coverage for python/lsst/obs/base/formatters/packages.py: 59%
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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 objects that support the standard
31 afw I/O readFits/writeFits methods.
32 """
33 supportedWriteParameters = frozenset({"format"})
34 supportedExtensions = frozenset({".yaml", ".pickle", ".pkl"})
36 @property
37 def extension(self) -> str:
38 # Default to YAML but allow configuration via write parameter
39 format = self.writeParameters.get("format", "yaml")
40 if format == "yaml": 40 ↛ 42line 40 didn't jump to line 42, because the condition on line 40 was never false
41 return ".yaml"
42 elif format == "pickle":
43 return ".pickle"
44 raise RuntimeError(f"Requested file format '{format}' is not supported for Packages")
46 def _readFile(self, path, pytype):
47 """Read a file from the path in FITS format.
49 Parameters
50 ----------
51 path : `str`
52 Path to use to open the file.
53 pytype : `type`
54 Class to use to read the serialized file.
56 Returns
57 -------
58 data : `object`
59 Instance of class ``pytype`` read from serialized file. None
60 if the file could not be opened.
61 """
62 if not os.path.exists(path):
63 return None
65 return pytype.read(path)
67 def _fromBytes(self, serializedDataset, pytype=None):
68 """Read the bytes object as a python object.
70 Parameters
71 ----------
72 serializedDataset : `bytes`
73 Bytes object to unserialize.
74 pytype : `type`
75 The Python type to be instantiated. Required.
77 Returns
78 -------
79 inMemoryDataset : `object`
80 The requested data as an object, or None if the string could
81 not be read.
82 """
83 # The format can not come from the formatter configuration
84 # because the current configuration has no connection to how
85 # the data were stored.
86 format = "yaml" if serializedDataset.startswith(b"!<lsst.base.Packages>") else "pickle"
87 return pytype.fromBytes(serializedDataset, format)
89 def _writeFile(self, inMemoryDataset):
90 """Write the in memory dataset to file on disk.
92 Parameters
93 ----------
94 inMemoryDataset : `object`
95 Object to serialize.
97 Raises
98 ------
99 Exception
100 The file could not be written.
101 """
102 inMemoryDataset.write(self.fileDescriptor.location.path)
104 def _toBytes(self, inMemoryDataset):
105 """Write the in memory dataset to a bytestring.
107 Parameters
108 ----------
109 inMemoryDataset : `object`
110 Object to serialize
112 Returns
113 -------
114 serializedDataset : `bytes`
115 YAML string encoded to bytes.
117 Raises
118 ------
119 Exception
120 The object could not be serialized.
121 """
122 format = "yaml" if self.extension == ".yaml" else "pickle"
123 return inMemoryDataset.toBytes(format)