A psycopg2 namedtuple cursor de-duplicating repeated fields names

dedup.py

"""
An example of named tuple cursor de-duplicating repeated fields names.

This is **not** a good idea: it makes the program unpredictable. But if you put
the foot and really look for a gun...

See https://github.com/psycopg/psycopg2/issues/418
"""
from itertools import count
from collections import OrderedDict, namedtuple
from psycopg2.extras import NamedTupleCursor


class DedupingNamedTupleCursor(NamedTupleCursor):
    def _make_nt(self):
        return namedtuple("Record",
            self.dedupe([d[0] for d in self.description or ()]))

    def dedupe(self, l):
        rv = OrderedDict()
        for i in l:
            if i not in rv:
                rv[i] = True
            else:
                for n in count(1):
                    ii = "%s_%d" % (i, n)
                    if ii not in rv:
                        rv[ii] = True
                        break
        return list(rv)


if __name__ == '__main__':
    import psycopg2
    cnn = psycopg2.connect("dbname=postgres",
        cursor_factory=DedupingNamedTupleCursor)
    cur = cnn.cursor()
    cur.execute("select 10 as a, 20 as b, 30 as c, 40 as c, 50 as c")
    print cur.fetchone()
    # Record(a=10, b=20, c=30, c_1=40, c_2=50)