issue2551142 - Import of retired node ... unique constraint failure. Title: Import of retired node with username after active node fails with unique constraint failure. More fixes needed for mysql and postgresql. mysql: add unique constraint for (keyvalue, __retired__) when creating class in the database. On schema change if class is changed, remove the unique constraint too. upgrade version of rdbms database from 5 to 6 to add constraint to all version 5 databases that were created as version 5 and didn't get the unique constraint. Make no changes on version 5 databases upgraded from version 4, the upgrade process to 5 added the constraint. Make no changes to other databases (sqlite, postgres) during upgrade from version 5 to 6. postgres: Handle the exception raised on unique constraint violation. The exception invalidates the database connection so it can't be used to recover from the exception. Added two new database methods: checkpoint_data - performs a db.commit under postgres does nothing on other backends restore_connection_on_error - does a db.rollback on postgres, does nothing on other backends with the rollback() done on the connection I can use the database connection to fixup the import that failed on the unique constraint. This makes postgres slower but without the commit after every imported object, the rollback will delete all the entries done up to this point. Trying to figure out how to make the caller do_import batch and recover from this failure is beyond me. Also dismissed having to process the export csv file before importing. Pushing that onto a user just seems wrong. Also since import/export isn't frequently done the lack of surprise on having a failing import and reduced load/frustration for the user seems worth it. Also the import can be run in verbose mode where it prints out a row as it is processed, so it may take a while, ut the user can get feedback. db_test-base.py: add test for upgrade from 5 to 6.

"""Parse the Accept-Language header as defined in RFC2616.

See http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.4
for details.  This module should follow the spec.
Author: Hernan M. Foffani (hfoffani@gmail.com)
Some use samples:

>>> parse("da, en-gb;q=0.8, en;q=0.7")
['da', 'en_gb', 'en']
>>> parse("en;q=0.2, fr;q=1")
['fr', 'en']
>>> parse("zn; q = 0.2 ,pt-br;q =1")
['pt_br', 'zn']
>>> parse("es-AR")
['es_AR']
>>> parse("es-es-cat")
['es_es_cat']
>>> parse("")
[]
>>> parse(None)
[]
>>> parse("   ")
[]
>>> parse("en,")
['en']
"""

import re
import heapq

# regexp for languange-range search
nqlre = "([A-Za-z]+[-[A-Za-z]+]*)$"
# regexp for languange-range search with quality value
qlre = r"([A-Za-z]+[-[A-Za-z]+]*);q=([\d\.]+)"
# both
lre = re.compile(nqlre + "|" + qlre)

whitespace = ' \t\n\r\v\f'
try:
    # Python 3.
    remove_ws = (str.maketrans('', '', whitespace),)
except AttributeError:
    # Python 2.
    remove_ws = (None, whitespace)


def parse(language_header):
    """parse(string_with_accept_header_content) -> languages list"""

    if language_header is None: return []

    # strip whitespaces.
    lh = language_header.translate(*remove_ws)

    # if nothing, return
    if lh == "": return []

    # split by commas and parse the quality values.
    pls = [lre.findall(x) for x in lh.split(',')]

    # drop uncomformant
    qls = [x[0] for x in pls if len(x) > 0]

    # use a heap queue to sort by quality values.
    # the value of each item is 1.0 complement.
    pq = []
    order=0
    for l in qls:
        order +=1
        if l[0] != '':
            heapq.heappush(pq, (0.0, order, l[0]))
        else:
            heapq.heappush(pq, (1.0-float(l[2]), order, l[1]))

    # get the languages ordered by quality
    # and replace - by _
    return [ heapq.heappop(pq)[2].replace('-','_') 
             for x in range(len(pq)) ]

if __name__ == "__main__":
    import doctest
    doctest.testmod()

# vim: set et sts=4 sw=4 :