Source Code for Module gavo.votable.tablewriter

  1  """ 
  2  Writing tabular data within VOTables. 
  3  """ 
  4   
  5  #c Copyright 2008-2019, the GAVO project 
  6  #c 
  7  #c This program is free software, covered by the GNU GPL.  See the 
  8  #c COPYING file in the source distribution. 
  9   
 10   
 11  from cStringIO import StringIO 
 12   
 13  from gavo import utils 
 14  from gavo.utils import stanxml 
 15  from gavo.votable import coding 
 16  from gavo.votable import common 
 17  from gavo.votable import enc_binary 
 18  from gavo.votable import enc_binary2 
 19  from gavo.votable import enc_tabledata 
 20  from gavo.votable.model import VOTable 
 21   
 22  _encoders = { 
 23          VOTable.TABLEDATA: enc_tabledata, 
 24          VOTable.BINARY: enc_binary, 
 25          VOTable.BINARY2: enc_binary2, 
 26  } 
 27   
 28   
 29 -def write(root, outputFile, xmlDecl=True): 
 30          """writes a VOTable to outputFile. 
 31   
 32          This is a compatiblity function that's in this place mainly for historical 
 33          reasons.  It's basically stanxml.write, except that the prefix of the root 
 34          element will be the empty prefix. 
 35          """ 
 36          return stanxml.write(root, outputFile, xmlDecl=xmlDecl, 
 37                  prefixForEmpty=root._prefix) 
 38   
 39   
 40 -def asString(root, xmlDecl=False): 
 41          """returns the V.VOTABLE root as a string. 
 42          """ 
 43          res = StringIO() 
 44          try: 
 45                  write(root, res, xmlDecl=xmlDecl) 
 46          except Exception: 
 47                  # something bad happened while generating the VOTable.  We probably 
 48                  # have unwound the element stack and left an error INFO, so probably 
 49                  # the document is all right.  Let's return it, but try to report an 
 50                  # error anyway if there's the infrastructure to do that 
 51                  utils.sendUIEvent("Error", "Exception during VOTable write (delivering" 
 52                          " the document anyway)") 
 53          return res.getvalue() 
 54   
 55   
 56 -class OverflowElement(stanxml.Stub): 
 57          """A container for VOTable elements that are written when it is 
 58          likely that a query has overflowed the limit. 
 59   
 60          This is for use with DelayedTable.  Instances of this can be 
 61          passed into overflowElement. 
 62   
 63          OverflowElements are constructed with the row limit and VOTable 
 64          material to be inserted when exactly row limit (or more) rows 
 65          have been written to the table. 
 66   
 67          All automatic namespace processing is turned off for the overflow 
 68          element.  This should not be a problem if you're embedding VOTable 
 69          elements into VOTables. 
 70          """ 
 71 -        def __init__(self, rowLimit, overflowStan): 
 72                  self.rowLimit, self.overflowStan = rowLimit, overflowStan 
 73                  self.rowsDelivered = None 
 74                  # disable namespace generation for write (ugly; fix this when 
 75                  # we've improved XML generation in xmlstan) 
 76                  self.overflowStan._fixedTagMaterial = "" 
 77   
 78 -        def __repr__(self): 
 79                  return "<Uninstanciated Overflow Warning>" 
 80   
 81 -        def setRowsDelivered(self, numRows): 
 82                  self.rowsDelivered = numRows 
 83           
 84 -        def write(self, outputFile): 
 85                  if self.rowLimit<=self.rowsDelivered: 
 86                          write(self.overflowStan, outputFile, xmlDecl=False) 
 87   
 88   
 89 -def DelayedTable(tableDefinition, rowIterator, contentElement, 
 90                  overflowElement=None, **attrs): 
 91          """returns tableDefinition such that when serialized, it contains 
 92          the data from rowIterator  
 93   
 94          rowIterator is an iterator yielding all rows from the table to be encoded, 
 95          tableDefinition is the TABLE element, and ContentElement is one of the 
 96          permitted DATA children from VOTable. 
 97   
 98          See the OverflowElement class for overflowElement. 
 99   
100          attrs are optional attributes to the content element. 
101          """ 
102          if contentElement not in _encoders: 
103                  raise common.VOTableError("Unsupported content element %s"%contentElement, 
104                          hint="Try something like TABLEDATA or BINARY") 
105          encodeRow = coding.buildEncoder(tableDefinition, _encoders[contentElement]) 
106   
107          def iterSerialized(): 
108                  numRows = 0 
109                  for row in rowIterator: 
110                          numRows += 1 
111                          yield encodeRow(row) 
112                  if overflowElement is not None: 
113                          overflowElement.setRowsDelivered(numRows) 
114           
115          content = contentElement(**attrs) 
116          content.text_ = "Placeholder for real data" 
117          content.iterSerialized = iterSerialized 
118   
119          return tableDefinition[ 
120                  VOTable.DATA[content]] 
121  # In a way, we'd like to have an overflow element here, assuming that 
122  # the table comes from a db query.  We could have that writing: 
123  #               overflowElement] 
124  # -- but TAP wants the overflow at the resource level.  So, we 
125  # put it there.  It will reflect the state of affairs for the last 
126  # table (which is probably as good as anything else). 
127