that object already got saved in DB after session.commit(). After that i am retrieving object which already stored in db. still same issue.
On Wed, Aug 5, 2015 at 7:41 PM, Mike Bayer <[email protected]> wrote: > > > On 8/5/15 9:24 AM, Abhishek Sharma wrote: > > Hi Team, > I have created customized data type using TypeDecorator approach. > > *from sqlalchemy import TypeDecorator, CLOB* > > *class ForceUnicodeClob(TypeDecorator): impl = CLOB* > > > > * def process_bind_param(self, value, dialect): if > isinstance(value, str): value = value.decode('utf-8', 'ignore') > return value* > > > > * def process_result_value(self, value, dialect): if value is > not None: value = "PREFIX" + value.decode('utf-8', 'ignore') > return value* > > > After this in my table definition I declared the type of one of column as > *ForceUnicodeClob.* > > *dlr_dclmr = Table('dlr_dclmr', metadata, Column('dclmr_ds', > ForceUnicodeClob(), primary_key=False))* > > After this I am executing the query on this table with > session.query(Model) , but when I am accessing result.*dclmr_ds *i am not > getting response prepended with "PREFIX". > > this can happen in the ORM if you retrieve a Model object that is already > present in the Session, which you created as a pending object: > > > model = Model(dclmr_ds='somestring') > session.add(model) > session.flush() > > m2 = session.query(Model).filter(...).first() > > assert model is m2 > > > that is, you get the same object back. The values of the attributes are > not updated unless you first expire that object, which normally happens > when you say session.commit(). > > > > > > > am i missing some steps? > > SQLAlchemy Version: 0.9.9 > We are using classic mapping for attributes mapping with DB columns. > > > > > On Tue, Aug 4, 2015 at 3:49 PM, Mike Bayer <[email protected]> > wrote: > >> >> >> On 8/4/15 1:41 PM, Abhishek Sharma wrote: >> >> is this followings two instructions compulsory while defining new type? >> m.drop_all(e) >> m.create_all(e) >> >> >> no that is just part of the demonstration script. >> >> >> >> this instructions are not feasible , because DB team already defined >> schema and normal user can not drop and create table. >> >> yup, that is a given >> >> >> >> On Tue, Aug 4, 2015 at 8:59 PM, Mike Bayer < <[email protected]> >> [email protected]> wrote: >> >>> >>> >>> 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]> >>> [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]> >>>> [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]>[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]>[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> >>>>>>> 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> >>>>>>> http://docs.sqlalchemy.org/en/rel_1_0/dialects/oracle.html#unicode >>>>>>> for background. >>>>>>> >>>>>>> >>>>>>> >>>>>>> -- >>>>>>> You received this message because you are subscribed to the Google >>>>>>> Groups "sqlalchemy" group. >>>>>>> To unsubscribe from this group and stop receiving emails from it, >>>>>>> send an email to <[email protected]> >>>>>>> [email protected]. >>>>>>> To post to this group, send email to <[email protected]> >>>>>>> [email protected]. >>>>>>> Visit this group at <http://groups.google.com/group/sqlalchemy> >>>>>>> http://groups.google.com/group/sqlalchemy. >>>>>>> For more options, visit <https://groups.google.com/d/optout> >>>>>>> https://groups.google.com/d/optout. >>>>>>> >>>>>>> >>>>>>> -- >>>>>>> You received this message because you are subscribed to a topic in >>>>>>> the Google Groups "sqlalchemy" group. >>>>>>> To unsubscribe from this topic, visit >>>>>>> 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