work on operator functions started

Author: rotten

rethinkdb-multicorn-fdw.py

@@ -1,11 +1,50 @@
 ## This is the implementation of the Multicorn ForeignDataWrapper class that does all of the work in RethinkDB
 ## R.Otten - 2014
 
+import operator
+
 from multicorn import ForeignDataWrapper
 from multicorn.utils import log_to_postgres, ERROR, WARNING, DEBUG
 
 import rethinkdb as r
 
+
+## Translate a string with an operator in it (eg. ">=") into a function.
+# hint from here:  http://stackoverflow.com/questions/1740726/python-turn-string-into-operator
+# Things that might come from PostgreSQL:  http://www.postgresql.org/docs/9.3/static/functions-comparison.html 
+def getOperatorFunction(opr):
+
+  '<': operator.lt
+  '>': operator.gt
+  '<=': operator.le
+  '>=': operator.ge
+  '=': operator.eq
+  '<>': operator.ne
+  '!=': operator.ne
+  '@>': operator.contains
+  '<@': 
+  '<<':
+  '>>':
+  '&<':
+  '>&':
+  '&&':
+  'is':
+  '~':
+  '~*':
+  '!~':
+  '!~*':
+  '~~':
+  'like':
+  '~~*':
+  'ilike':
+  'similar to':
+  # I'm not sure we'll get "between" so it isn't implemented for now.
+  # I'm not sure 'OR' will get through either as an operator.
+  # We are not going to try to support Geometric object operators at this time.
+  # Nor will we support the Network Address operators yet.
+  # There aren't any json specific comparison operators yet (if there were, we would want to try to implement them)
+
+## The Foreign Data Wrapper Class:
 class RethinkdbFDW(ForeignDataWrapper):
 
     """
@@ -51,8 +90,8 @@ def execute(self, quals, columns):
 
         for qual in quals:
 
-            ## -- this isn't right yet.
-            myQuery = myQuery.filter(qual.field_name + ' ' + qual.operator + ' ' + qual.value)
+            operatorFunction = getOperatorFunction(qual.operator)
+            myQuery = myQuery.filter(operatorFunction(r.row[qual.field_name], qual.value))
 
          return _run_rethinkdb_action(action=myQuery)