Re: iterating over DictRow
От | Adrian Klaver |
---|---|
Тема | Re: iterating over DictRow |
Дата | |
Msg-id | 27c3e20a-3ff8-28a7-b16b-4d052628f02d@aklaver.com обсуждение исходный текст |
Ответ на | iterating over DictRow (Karsten Hilbert <Karsten.Hilbert@gmx.net>) |
Список | psycopg |
On 9/23/20 2:54 PM, Karsten Hilbert wrote: > Dear all, > > I cannot currently wrap my head around why I am seeing this: > > 2020-09-23 23:30:23 gmConnectionPool.py::<module>() #87): psycopg2 module version: 2.8.5 (dt dec pq3 ext) > 2020-09-23 23:30:23 gmConnectionPool.py::<module>() #88): PostgreSQL via DB-API module "<module 'psycopg2' from '/usr/lib/python3/dist-packages/psycopg2/__init__.py'>":API level 2.0, thread safety 2, parameter style "pyformat" > 2020-09-23 23:30:23 gmConnectionPool.py::<module>() #89): libpq version (compiled in): 120002 > 2020-09-23 23:30:23 gmConnectionPool.py::<module>() #90): libpq version (loaded now) : 120004 > ... > 2020-09-23 23:30:28 gmConnectionPool.py::__log_on_first_contact() #445): heed Prime Directive > 2020-09-23 23:30:28 gmConnectionPool.py::__log_on_first_contact() #457): PostgreSQL version (numeric): 11.7 > ... > 2020-09-23 23:31:02 gmMacro.py::_get_variant_diagnoses() #2442): [[260, 'L: Bewegungsapparat', False, 'B', 'clin.health_issue'],[260, 'K: aHT/HI', False, 'B', 'clin.health_issue'], [260, 'D: Verdauung', False, None, 'clin.health_issue']] > 2020-09-23 23:31:02 gmMacro.py::_get_variant_diagnoses() #2443): <class 'psycopg2.extras.DictRow'> > 2020-09-23 23:31:02 gmMacro.py::_escape_dict() #2851): 260 > 2020-09-23 23:31:02 gmMacro.py::__getitem__() #880): placeholder handling error: diagnoses:: \item %(diagnosis)s:: > Traceback (most recent call last): > File "/home/ncq/Projekte/gm/git/gnumed/gnumed/Gnumed/wxpython/gmMacro.py", line 869, in __getitem__ > val = handler(data = options) > File "/home/ncq/Projekte/gm/git/gnumed/gnumed/Gnumed/wxpython/gmMacro.py", line 2445, in _get_variant_diagnoses > return '\n'.join(template % self._escape_dict(dx, none_string = '?', bool_strings = [_('yes'), _('no')]) for dxin selected) > File "/home/ncq/Projekte/gm/git/gnumed/gnumed/Gnumed/wxpython/gmMacro.py", line 2445, in <genexpr> > return '\n'.join(template % self._escape_dict(dx, none_string = '?', bool_strings = [_('yes'), _('no')]) for dxin selected) > File "/home/ncq/Projekte/gm/git/gnumed/gnumed/Gnumed/wxpython/gmMacro.py", line 2852, in _escape_dict > val = the_dict[field] > File "/usr/lib/python3/dist-packages/psycopg2/extras.py", line 169, in __getitem__ > return super(DictRow, self).__getitem__(x) > IndexError: list index out of range > > This line logs a list of DictRow's: > > 2020-09-23 23:31:02 gmMacro.py::_get_variant_diagnoses() #2442): [[260, 'L: Bewegungsapparat', False, 'B', 'clin.health_issue'],[260, 'K: aHT/HI', False, 'B', 'clin.health_issue'], [260, 'D: Verdauung', False, None, 'clin.health_issue']] > > as evidenced here: > > 2020-09-23 23:31:02 gmMacro.py::_get_variant_diagnoses() #2443): <class 'psycopg2.extras.DictRow'> > > The logging code: > > _log.debug('%s', selected) > _log.debug('%s', type(selected[0])) > > and then iterates over the list of DictRow's as per list > comprehension like so: > > return '\n'.join(template % self._escape_dict(dx, none_string = '?', bool_strings = [_('yes'), _('no')]) for dx inselected) > > where _escape_dict() does this: > > def _escape_dict(self, the_dict=None, date_format='%Y %b %d %H:%M', none_string='', bool_strings=None): > data = {} > for field in the_dict: > _log.debug('%s', field) > val = the_dict[field] > if val is None: > ... > if isinstance(val, bool): > ... > if isinstance(val, datetime.datetime): > ... > if self.__esc_style in ['latex', 'tex']: > ... > elif self.__esc_style in ['xetex', 'xelatex']: > ... > return data > > Iterating over the_dict should work for lists (produces > values) OR dicts (produces keys, under py3). It seems as if > the line > > for field in the_dict: # I hoped to iterate over the keys = column names > > somehow "decides": "currently we are treating the_dict as a > list (after all, it is a DictRow, which _can_ be treated as a > list) which then "turns" the dict-style access in > > val = the_dict[field] > > into a list access. > > Somehow I have a feeling that due to the type of "field" > -- it being integer (namely, a primary key) -- forces > > the_dict[field] > > to attempt a list-style index based access (which fails, due > to there not being 260 columns in the SQL query result :-) > > Solutions that come to mind: > > _Must_ I use RealDictCursor() to safely avoid this trap ? > > (or else dict()ify DictRow's as needed) > > Any insights to be had ? Maybe?: con = psycopg2.connect("dbname=production host=localhost user=postgres", cursor_factory=DictCursor) cur = con.cursor() cur.execute("select * from cell_per") the_dict = cur.fetchall() # Example 1 for row in the_dict: for fld in row: print(fld) # Return just field values ... 4 HERB 3.5 19 None 2020-09-22 17:34:31 None postgres herb none HR3 #Example 2 for row in the_dict: for fld in dict(row): print(fld, row[fld]) Showing the field name and field value. ... line_id 4 category HERB 3.5 cell_per 19 ts_insert None ts_update 2020-09-22 17:34:31 user_insert None user_update postgres plant_type herb season none short_category HR3 > > Thanks, > Karsten > -- > GPG 40BE 5B0E C98E 1713 AFA6 5BC0 3BEA AC80 7D4F C89B > > -- Adrian Klaver adrian.klaver@aklaver.com
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