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API: Stop modifying SQL column and names, and warn when pertinent. #6902

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Merged
merged 1 commit into from
Apr 22, 2014
Merged

API: Stop modifying SQL column and names, and warn when pertinent. #6902

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34 changes: 18 additions & 16 deletions pandas/io/sql.py
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@

import warnings
import itertools
import re
import numpy as np

import pandas.core.common as com
Expand Down Expand Up @@ -38,11 +39,6 @@ def _convert_params(sql, params):
return args


def _safe_col_name(col_name):
#TODO: probably want to forbid database reserved names, such as "database"
return col_name.strip().replace(' ', '_')


def _handle_date_column(col, format=None):
if isinstance(format, dict):
return to_datetime(col, **format)
Expand Down Expand Up @@ -587,11 +583,11 @@ def _index_name(self, index, index_label):
def _create_table_statement(self):
from sqlalchemy import Table, Column

safe_columns = map(_safe_col_name, self.frame.dtypes.index)
columns = list(map(str, self.frame.columns))
column_types = map(self._sqlalchemy_type, self.frame.dtypes)

columns = [Column(name, typ)
for name, typ in zip(safe_columns, column_types)]
for name, typ in zip(columns, column_types)]

if self.index is not None:
for i, idx_label in enumerate(self.index[::-1]):
Expand Down Expand Up @@ -836,6 +832,11 @@ def _create_sql_schema(self, frame, table_name):
}


_SAFE_NAMES_WARNING = ("The spaces in these column names will not be changed."
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A space after changed. is missing

"In pandas versions < 0.14, spaces were converted to "
"underscores.")


class PandasSQLTableLegacy(PandasSQLTable):
"""Patch the PandasSQLTable for legacy support.
Instead of a table variable just use the Create Table
Expand All @@ -847,19 +848,18 @@ def create(self):
self.pd_sql.execute(self.table)

def insert_statement(self):
# Replace spaces in DataFrame column names with _.
safe_names = [_safe_col_name(n) for n in self.frame.dtypes.index]
names = list(map(str, self.frame.columns))
flv = self.pd_sql.flavor
br_l = _SQL_SYMB[flv]['br_l'] # left val quote char
br_r = _SQL_SYMB[flv]['br_r'] # right val quote char
wld = _SQL_SYMB[flv]['wld'] # wildcard char

if self.index is not None:
[safe_names.insert(0, idx) for idx in self.index[::-1]]
[names.insert(0, idx) for idx in self.index[::-1]]

bracketed_names = [br_l + column + br_r for column in safe_names]
bracketed_names = [br_l + column + br_r for column in names]
col_names = ','.join(bracketed_names)
wildcards = ','.join([wld] * len(safe_names))
wildcards = ','.join([wld] * len(names))
insert_statement = 'INSERT INTO %s (%s) VALUES (%s)' % (
self.name, col_names, wildcards)
return insert_statement
Expand All @@ -881,13 +881,15 @@ def insert(self):
def _create_table_statement(self):
"Return a CREATE TABLE statement to suit the contents of a DataFrame."

# Replace spaces in DataFrame column names with _.
safe_columns = [_safe_col_name(n) for n in self.frame.dtypes.index]
columns = list(map(str, self.frame.columns))
pat = re.compile('\s+')
if any(map(pat.search, columns)):
warnings.warn(_SAFE_NAMES_WARNING)
column_types = [self._sql_type_name(typ) for typ in self.frame.dtypes]

if self.index is not None:
for i, idx_label in enumerate(self.index[::-1]):
safe_columns.insert(0, idx_label)
columns.insert(0, idx_label)
column_types.insert(0, self._sql_type_name(self.frame.index.get_level_values(i).dtype))

flv = self.pd_sql.flavor
Expand All @@ -898,7 +900,7 @@ def _create_table_statement(self):
col_template = br_l + '%s' + br_r + ' %s'

columns = ',\n '.join(col_template %
x for x in zip(safe_columns, column_types))
x for x in zip(columns, column_types))
template = """CREATE TABLE %(name)s (
%(columns)s
)"""
Expand Down
14 changes: 14 additions & 0 deletions pandas/io/tests/test_sql.py
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Original file line number Diff line number Diff line change
Expand Up @@ -550,6 +550,11 @@ def test_to_sql_index_label_multiindex(self):
'test_index_label', self.conn, if_exists='replace',
index_label='C')

def test_integer_col_names(self):
df = DataFrame([[1, 2], [3, 4]], columns=[0, 1])
sql.to_sql(df, "test_frame_integer_col_names", self.conn,
if_exists='replace')


class TestSQLApi(_TestSQLApi):
"""
Expand Down Expand Up @@ -661,10 +666,19 @@ def test_read_sql_delegate(self):
self.assertRaises(ValueError, sql.read_sql, 'iris', self.conn,
flavor=self.flavor)

def test_safe_names_warning(self):
# GH 6798
df = DataFrame([[1, 2], [3, 4]], columns=['a', 'b ']) # has a space
# warns on create table with spaces in names
with tm.assert_produces_warning():
sql.to_sql(df, "test_frame3_legacy", self.conn,
flavor="sqlite", index=False)


#------------------------------------------------------------------------------
#--- Database flavor specific tests


class _TestSQLAlchemy(PandasSQLTest):
"""
Base class for testing the sqlalchemy backend.
Expand Down