Coverage for python/lsst/verify/jsonmixin.py: 30%

31 statements  

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1# This file is part of verify. 

2# 

3# Developed for the LSST Data Management System. 

4# This product includes software developed by the LSST Project 

5# (https://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 <https://www.gnu.org/licenses/>. 

21__all__ = ['JsonSerializationMixin'] 

22 

23import abc 

24import json 

25 

26 

27class JsonSerializationMixin(metaclass=abc.ABCMeta): 

28 """Mixin that provides JSON serialization support to subclasses. 

29 

30 Subclasses must implement the `json` method. The method returns a `dict` 

31 that can be serialized to JSON. Use the `jsonify_dict` method to handle 

32 the conversion of iterables, numbers, strings, booleans and 

33 `JsonSerializationMixin`-compatible objects into a JSON-serialiable object. 

34 """ 

35 

36 @abc.abstractproperty 

37 def json(self): 

38 """`dict` that can be serialized as semantic JSON, compatible with 

39 the SQUASH metric service. 

40 """ 

41 pass 

42 

43 @staticmethod 

44 def jsonify_dict(d): 

45 """Recursively build JSON-renderable objects on all values in a dict. 

46 

47 Parameters 

48 ---------- 

49 d : `dict` 

50 Dictionary to convert into a JSON-serializable object. Values 

51 are recursively JSON-ified. 

52 

53 Returns 

54 ------- 

55 json_dict : `dict` 

56 Dictionary that can be serialized to JSON. 

57 

58 Examples 

59 -------- 

60 Subclasses can use this method to prepare output in their `json`-method 

61 implementation. For example:: 

62 

63 def json(self): 

64 return JsonSerializationMixin.jsonify_dict({ 

65 'value': self.value, 

66 }) 

67 """ 

68 json_dict = {} 

69 for k, v in d.items(): 

70 json_dict[k] = JsonSerializationMixin._jsonify_value(v) 

71 return json_dict 

72 

73 @staticmethod 

74 def _jsonify_list(lst): 

75 """Recursively convert items of a list into JSON-serializable objects. 

76 """ 

77 json_array = [] 

78 for v in lst: 

79 json_array.append(JsonSerializationMixin._jsonify_value(v)) 

80 return json_array 

81 

82 @staticmethod 

83 def _jsonify_value(v): 

84 """Convert an object into a JSON-serizable object, recursively 

85 processes dicts and iterables. 

86 """ 

87 if isinstance(v, JsonSerializationMixin): 

88 return v.json 

89 elif isinstance(v, dict): 

90 return JsonSerializationMixin.jsonify_dict(v) 

91 elif isinstance(v, (list, tuple, set)): 

92 return JsonSerializationMixin._jsonify_list(v) 

93 else: 

94 return v 

95 

96 def write_json(self, filepath): 

97 """Write JSON to a file. 

98 

99 Parameters 

100 ---------- 

101 filepath : `str` 

102 Destination file name for JSON output. 

103 """ 

104 with open(filepath, 'w') as outfile: 

105 json.dump(self.json, outfile, sort_keys=True, indent=2)