gavo.dm.vodml

53 """a vo-dml model. 54 55 These are usually constructed using the fromPrefix constructor, 56 which uses a built-in mapping from well-known prefix to VO-DML file 57 to populate the model. 58 """ 59 60 # non-well-known models can be fed in through fromFile; they well 61 # be entered here and can then be obtained through fromPrefix 62 # as long as the don't clash with KNOWN_MODELS. 63 64 _modelsReadFromFile = {} 65

66 - def __init__(self, prefix, dmlTree):

67 self.prefix = prefix 68 self.title = self.version = None 69 self.version = self.url = None 70 self.description = None 71 self.dmlTree = dmlTree 72 self.__idIndex = None 73 if self.dmlTree: 74 self._getModelMeta()

75 76 @classmethod

77 - def fromPrefix(cls, prefix):

78 """returns a VO-DML model for a well-known prefix. 79 80 User code should typically use the getModelFromPrefix function. 81 """ 82 if prefix in cls._modelsReadFromFile: 83 return cls._modelsReadFromFile[prefix] 84 85 inF = openModelFile(prefix) 86 try: 87 try: 88 res = cls(prefix, ElementTree.parse(inF)) 89 # as long as we can't get the URL from the XML, patch it in here 90 res.url = KNOWN_MODELS[prefix][1] 91 return res 92 except Exception as ex: 93 raise base.ui.logOldExc( 94 base.StructureError("Failure to parse VO-DML for prefix %s: %s"%( 95 prefix, repr(ex)))) 96 finally: 97 inF.close()

98 99 @classmethod

100 - def fromFile(cls, src, srcURL="http //not.given/invalid"):

101 """returns a VO-DML model from src. 102 103 src can either be a file name (interpreted relative to the root 104 of DaCHS' VO-DML repository) or an open file (which will be closed 105 as a side effect of this function). 106 107 This is intended for documents using non-standard models with custom 108 prefixes (i.e., not known to DaCHS). 109 """ 110 if hasattr(src, "read"): 111 inF = src 112 else: 113 inF = openModelFile(src) 114 115 try: 116 tree = ElementTree.parse(inF) 117 prefix = tree.find("name").text 118 res = cls(prefix, tree) 119 res.url = srcURL 120 121 if prefix not in KNOWN_MODELS: 122 cls._modelsReadFromFile[prefix] = res 123 return res 124 finally: 125 inF.close()

126 127 @property

128 - def idIndex(self):

129 """returns a dictionary mapping vodmlids to elementtree objects. 130 """ 131 if self.__idIndex is None: 132 self.__idIndex = self._createIndex() 133 return self.__idIndex

134

135 - def _createIndex(self):

136 """returns a dictionary mapping vodml-ids to elementtree objects. 137 138 Use the idIndex property rather than this function, as the former will 139 cache the dicts. 140 """ 141 res = {} 142 for element in self.dmlTree.getroot().iter(): 143 id = element.find("vodml-id") 144 if id is not None: 145 res[id.text] = element 146 return res

147

148 - def _getModelMeta(self):

149 """sets some metadata on the model from the parsed VO-DML. 150 151 This will fail silently (i.e., the metadata will remain on its 152 default). 153 154 Metadata obtained so far includes: title, version, description, 155 """ 156 try: 157 self.title = self.dmlTree.find("title").text 158 self.version = self.dmlTree.find("version").text 159 self.description = self.dmlTree.find("description").text 160 except AttributeError: 161 # probably the VO-DML file is bad; just fall through to 162 # non-validatable model. 163 pass

164

165 - def _resolveNonLocalVODMLId(self, id):

166 """returns an etree Element pointed to by the VO-DML id 167 168 This is a helper for getByVODMLId and works by sucessively 169 trying shorter pieces of id. 170 171 This returns None on a failure rather than raising an exception 172 (because it's really a helper for getByVODMLId). 173 """ 174 parts = id.split(".") 175 for splitPoint in range(len(parts)-1, 0, -1): 176 newId = ".".join(parts[:splitPoint]) 177 if newId in self.idIndex: 178 # this should be an attribute definition. Now follow 179 # the chain of attribute names to the end 180 att = self.idIndex[newId] 181 thisType = resolveVODMLId( 182 att.find("datatype").find("vodml-ref").text) 183 184 for attName in parts[splitPoint:]: 185 att = getAttributeDefinition(thisType, attName) 186 thisType = resolveVODMLId( 187 att.find("datatype").find("vodml-ref").text) 188 return att

189 # fall through on failure 190

191 - def getByVODMLId(self, vodmlId):

192 """returns the element with vodmlId. 193 194 This raises a NotFoundError for elements that are not present. 195 196 This can be used with or without the prefix. The prefix is not 197 validated, though. 198 """ 199 if ":" in vodmlId: 200 vodmlId = vodmlId.split(":", 1)[1] 201 202 # We may have to follow ids through several documents based on types. 203 # First try to directly find the element. 204 if vodmlId in self.idIndex: 205 return self.idIndex[vodmlId] 206 207 res = self._resolveNonLocalVODMLId(vodmlId) 208 if res: 209 return res 210 else: 211 raise base.NotFoundError(vodmlId, "data model element", 212 self.prefix+" data model")

213

214 - def getAttributeMeta(self, vodmlId):

215 """returns a metadata dictionary for a VO-DML element with vodmlId. 216 217 This includes datatype add description. If vodmlId points to 218 the value of a quantity, the associate unit and ucd attributes 219 are returned as well. 220 221 If the vodmlId cannot be found, a NotFoundError is raised. 222 """ 223 raise NotImplementedError("We've not yet figured out how this is" 224 " supposed to work.")

225

226 - def getVOT(self, ctx, instance):

227 """returns xmlstan for a VOTable declaration of this DM. 228 """ 229 return V.MODEL[ 230 V.NAME(version=self.version)[self.prefix], 231 V.URL[self.url]]

Source Code for Module gavo.dm.vodml