On 8/4/15 7:41 AM, Abhishek Sharma wrote:
in case lot of overhead will be there so it is better to use that
column label only
well it doesn't work anyway because data from a CLOB is not in
cx_oracle's world a "String", it's a LOB. The CLOB / NCLOB types for
cx_oracle are organized in their own way where only NCLOB actually has
unicode handling capability, regardless of the coerce_to_unicode or
convert_unicode flags; CLOB does not. So either use NCLOB, or build
out your own convert unicode, here is a demo:
from sqlalchemy import create_engine, CLOB, Table, MetaData, Column,
select, TypeDecorator
from sqlalchemy.dialects.oracle import NCLOB
e = create_engine("oracle+cx_oracle://scott:tiger@xe", echo='debug')
class ForceUnicodeClob(TypeDecorator):
impl = CLOB
def process_result_value(self, value, dialect):
if value is not None:
value = value.decode('utf-8')
return value
m = MetaData()
t = Table('test', m, Column('data1', NCLOB()), Column('data2',
ForceUnicodeClob()))
m.drop_all(e)
m.create_all(e)
e.execute(t.insert(), data1=u'unicode', data2=u'unicode')
result = e.execute(select([t.c.data1, t.c.data2]))
value1, value2 = result.fetchone()
print repr(value1), repr(value2)
On Tue, Aug 4, 2015 at 6:15 AM, Mike Bayer <[email protected]
<mailto:[email protected]>> wrote:
On 8/4/15 5:47 AM, Abhishek Sharma wrote:
applying convert_unicode to CLOB type does not have any effect.
Still I am getting str type object from sqlalchemy for CLOB type
column
have you tried the coerce_to_unicode flag on create_engine() ?
On Mon, Aug 3, 2015 at 1:27 PM, Mike Bayer
<[email protected] <mailto:[email protected]>> wrote:
On 8/3/15 1:04 PM, Abhishek Sharma wrote:
what about CLOB type? Unicode only handles String type. Do i
need to use convert_unicode there?
if your CLOB expects non-ascii characters then yes.
though on Oracle I thought you really need to be using NCLOB
for a col that stores unicode.
On Mon, Aug 3, 2015 at 6:56 PM, Mike Bayer
<[email protected] <mailto:[email protected]>>
wrote:
On 8/1/15 12:12 PM, Abhishek Sharma wrote:
Thanks for help. But still i have confusion over
encoding and decoding procedure which will take place
before retrieving and storing the results in DB.
In case if i am not using convert_unicode option and
data type is String so python process will give str
object to sqlalchemy at the time of insert record in DB
using ORM. So will alchemy store that object in encoded
form?. So at the time of retrieving ORM will give str
object for String type column to python and python
decode that object with default encoding?
Can i simply use Unicode Data type for columns where
there might be chance of using non ascii data?
if you know that your unicode data is on specific
columns then yes, the Unicode type plugs in an
encoder/decoder for those backends that require it.
On Thu, Jul 30, 2015 at 2:55 AM, Mike Bayer
<[email protected]
<mailto:[email protected]>> wrote:
On 7/29/15 2:23 PM, Abhishek Sharma wrote:
We are using sqlalchemy version 0.7, python 2.7
and oracle Database.
We have ASCII as default python encoding and DB
have ISO-8052 encoding. Our DB tables contains
some of characters which are out of ASCII range.
So when we are running query on those tables we
are getting Unicode Decode error saying "ASCII"
codec can not decode. This error we are getting
without accessing model attributes.
How i can handle these errors without changing
python default encoding.
Oracle's client encoding is controlled by the
NLS_LANG environment variable. That has to be set
correctly first off (see
http://www.oracle.com/technetwork/products/globalization/nls-lang-099431.html).
If you have non-ASCII strings encoded in datatypes
that are explicitly not of type NVARCHAR or NCLOB ,
or you're relying on a lot of raw SQL, and you are
still getting errors, I would set the
"coerce_to_unicode=True" flag on create_engine(),
which allows cx_Oracle's unicode facilities to take
place fully for all string data being returned, at
the expense of some performance. See
http://docs.sqlalchemy.org/en/rel_1_0/dialects/oracle.html#unicode
for background.
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