1 | """Helper functions and class to map between OGM Elements <-> DB Elements""" |
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2 | |||
3 | from typing import Any, Dict |
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4 | import functools |
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5 | import logging |
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6 | |||
7 | from goblin import exception |
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8 | from gremlin_python.process.traversal import T |
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9 | |||
10 | logger = logging.getLogger(__name__) |
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11 | |||
12 | |||
13 | def map_props_to_db(element, mapping): |
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14 | """Convert OGM property names/values to DB property names/values""" |
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15 | property_tuples = [] |
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16 | props = mapping.ogm_properties |
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17 | for ogm_name, (db_name, data_type) in props.items(): |
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18 | val = getattr(element, ogm_name, None) |
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19 | if val and isinstance(val, (list, set)): |
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20 | card = None |
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21 | for v in val: |
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22 | metaprops = get_metaprops(v, v.__mapping__) |
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23 | property_tuples.append((card, db_name, data_type.to_db( |
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24 | v.value), metaprops)) |
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25 | card = v.cardinality |
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26 | else: |
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27 | if hasattr(val, '__mapping__'): |
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28 | metaprops = get_metaprops(val, val.__mapping__) |
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29 | val = val.value |
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30 | else: |
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31 | metaprops = None |
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32 | property_tuples.append((None, db_name, data_type.to_db(val), |
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33 | metaprops)) |
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34 | return property_tuples |
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35 | |||
36 | |||
37 | def get_metaprops(vertex_property, mapping): |
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38 | props = mapping.ogm_properties |
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39 | metaprops = {} |
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40 | for ogm_name, (db_name, data_type) in props.items(): |
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41 | val = getattr(vertex_property, ogm_name, None) |
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42 | metaprops[db_name] = data_type.to_db(val) |
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43 | return metaprops |
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44 | |||
45 | |||
46 | def map_vertex_to_ogm(result, props, element, *, mapping=None): |
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47 | """Map a vertex returned by DB to OGM vertex""" |
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48 | props.pop('id') |
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49 | label = props.pop('label') |
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50 | for db_name, value in props.items(): |
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51 | metaprops = [] |
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52 | if len(value) > 1: |
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53 | values = [] |
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54 | for v in value: |
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55 | if isinstance(v, dict): |
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56 | val = v.pop('value') |
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57 | v.pop('key') |
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58 | vid = v.pop('id') |
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59 | if v: |
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60 | v['id'] = vid |
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61 | metaprops.append((val, v)) |
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62 | values.append(val) |
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63 | else: |
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64 | values.append(v) |
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65 | value = values |
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66 | else: |
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67 | value = value[0] |
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68 | if isinstance(value, dict): |
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69 | val = value.pop('value') |
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70 | value.pop('key') |
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71 | vid = value.pop('id') |
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72 | if value: |
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73 | value['id'] = vid |
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74 | metaprops.append((val, value)) |
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75 | value = val |
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76 | name, data_type = mapping.db_properties.get(db_name, (db_name, None)) |
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77 | if data_type: |
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78 | value = data_type.to_ogm(value) |
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79 | setattr(element, name, value) |
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80 | if metaprops: |
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81 | vert_prop = getattr(element, name) |
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82 | if hasattr(vert_prop, 'mapper_func'): |
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83 | # Temporary hack for managers |
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84 | vert_prop.mapper_func(metaprops, vert_prop) |
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85 | else: |
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86 | vert_prop.__mapping__.mapper_func(metaprops, vert_prop) |
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87 | setattr(element, '__label__', label) |
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88 | setattr(element, 'id', result.id) |
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89 | return element |
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90 | |||
91 | |||
92 | # TODO: temp hack |
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93 | def get_hashable_id(val: Dict[str, Any]) -> Any: |
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94 | if isinstance(val, dict) and "@type" in val and "@value" in val: |
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95 | if val["@type"] == "janusgraph:RelationIdentifier": |
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96 | val = val["@value"].get("value", val["@value"]["relationId"]) |
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97 | return val |
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98 | |||
99 | |||
100 | |||
101 | def map_vertex_property_to_ogm(result, element, *, mapping=None): |
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102 | """Map a vertex returned by DB to OGM vertex""" |
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103 | for (val, metaprops) in result: |
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104 | if isinstance(element, list): |
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105 | current = element.vp_map.get(get_hashable_id(metaprops['id'])) |
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106 | # This whole system needs to be reevaluated |
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107 | if not current: |
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108 | current = element(val) |
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109 | if isinstance(current, list): |
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110 | for vp in current: |
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111 | if not hasattr(vp, '_id'): |
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112 | element.vp_map[get_hashable_id( |
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113 | metaprops['id'])] = vp |
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114 | current = vp |
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115 | break |
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116 | elif isinstance(element, set): |
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117 | current = element(val) |
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118 | else: |
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119 | current = element |
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120 | for db_name, value in metaprops.items(): |
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121 | name, data_type = mapping.db_properties.get( |
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122 | db_name, (db_name, None)) |
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123 | if data_type: |
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124 | value = data_type.to_ogm(value) |
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125 | setattr(current, name, value) |
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126 | |||
127 | |||
128 | def map_edge_to_ogm(result, props, element, *, mapping=None): |
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129 | """Map an edge returned by DB to OGM edge""" |
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130 | props.pop(T.id) |
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131 | label = props.pop(T.label) |
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132 | for db_name, value in props.items(): |
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133 | name, data_type = mapping.db_properties.get(db_name, (db_name, None)) |
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134 | if data_type: |
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135 | value = data_type.to_ogm(value) |
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136 | setattr(element, name, value) |
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137 | setattr(element, '__label__', label) |
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138 | setattr(element, 'id', result.id) |
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139 | # Currently not included in graphson |
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140 | # setattr(element.source, '__label__', result.outV.label) |
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141 | # setattr(element.target, '__label__', result.inV.label) |
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142 | sid = result.outV.id |
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143 | esid = getattr(element.source, 'id', None) |
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144 | if _check_id(sid, esid): |
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145 | from goblin.element import GenericVertex |
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146 | element.source = GenericVertex() |
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147 | tid = result.inV.id |
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148 | etid = getattr(element.target, 'id', None) |
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149 | if _check_id(tid, etid): |
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150 | from goblin.element import GenericVertex |
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151 | element.target = GenericVertex() |
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152 | setattr(element.source, 'id', sid) |
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153 | setattr(element.target, 'id', tid) |
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154 | return element |
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155 | |||
156 | |||
157 | def _check_id(rid, eid): |
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158 | if eid and rid != eid: |
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159 | logger.warning('Edge vertex id has changed') |
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160 | return True |
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161 | return False |
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162 | |||
163 | |||
164 | # DB <-> OGM Mapping |
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165 | def create_mapping(namespace, properties): |
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166 | """Constructor for :py:class:`Mapping`""" |
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167 | element_type = namespace['__type__'] |
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168 | if element_type == 'vertex': |
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169 | mapping_func = map_vertex_to_ogm |
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170 | mapping = Mapping(namespace, element_type, mapping_func, properties) |
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171 | elif element_type == 'edge': |
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172 | mapping_func = map_edge_to_ogm |
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173 | mapping = Mapping(namespace, element_type, mapping_func, properties) |
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174 | elif element_type == 'vertexproperty': |
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175 | mapping_func = map_vertex_property_to_ogm |
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176 | mapping = Mapping(namespace, element_type, mapping_func, properties) |
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177 | else: |
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178 | mapping = None |
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179 | return mapping |
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180 | |||
181 | |||
182 | class Mapping: |
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183 | """ |
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184 | This class stores the information necessary to map between an OGM element |
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185 | and a DB element. |
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186 | """ |
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187 | |||
188 | def __init__(self, namespace, element_type, mapper_func, properties): |
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189 | self._label = namespace['__label__'] |
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190 | self._element_type = element_type |
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191 | self._mapper_func = functools.partial(mapper_func, mapping=self) |
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192 | self._db_properties = {} |
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193 | self._ogm_properties = {} |
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194 | self._map_properties(properties) |
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195 | |||
196 | @property |
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197 | def label(self): |
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198 | """Element label""" |
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199 | return self._label |
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200 | |||
201 | @property |
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202 | def mapper_func(self): |
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203 | """Function responsible for mapping db results to ogm""" |
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204 | return self._mapper_func |
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205 | |||
206 | @property |
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207 | def db_properties(self): |
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208 | """A dictionary of property mappings""" |
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209 | return self._db_properties |
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210 | |||
211 | @property |
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212 | def ogm_properties(self): |
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213 | """A dictionary of property mappings""" |
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214 | return self._ogm_properties |
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215 | |||
216 | def __getattr__(self, value): |
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217 | try: |
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218 | mapping, _ = self._ogm_properties[value] |
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219 | return mapping |
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220 | except KeyError: |
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221 | raise exception.MappingError( |
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222 | "unrecognized property {} for class: {}".format( |
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223 | value, self._element_type)) |
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224 | |||
225 | def _map_properties(self, properties): |
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226 | for name, prop in properties.items(): |
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227 | data_type = prop.data_type |
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228 | if prop.db_name: |
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229 | db_name = prop.db_name |
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230 | else: |
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231 | db_name = name |
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232 | if hasattr(prop, '__mapping__'): |
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233 | if not self._element_type == 'vertex': |
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234 | raise exception.MappingError( |
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235 | 'Only vertices can have vertex properties') |
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236 | self._db_properties[db_name] = (name, data_type) |
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237 | self._ogm_properties[name] = (db_name, data_type) |
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238 | |||
239 | def __repr__(self): |
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240 | return '<{}(type={}, label={}, properties={})>'.format( |
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241 | self.__class__.__name__, self._element_type, self._label, |
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242 | self._ogm_properties) |
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243 |