I found the missing space before literal_processor in my earlier listing, poor
font selection hid that pretty well - still not sure why I couldn't see that
earlier apologies again for that post.
The new listing below now runs to completion but literal_processor method is
not called for my UDT 'ArrayType', it's just being bound as the value NULL.
It's still not clear to me if there is an issue with literal_processor being
called, or I'm misusing the LiteralBindParam recipe from earlier post, or
possibly still and issue with the array type udt.
I'm not sure what type should be used in following line; currently just None.
a = LiteralBindParam(None, ArrayType([1,2,3,4,5]))
I'm also not sure if the return from ArrayType get_col_spec is valid; or if
this needs to be registered or defined somewhere.
def get_col_spec(self):
return "ARRAY"
------------------------
import os
import sqlalchemy
from sqlalchemy.orm import sessionmaker
from sqlalchemy import MetaData
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import func
from sqlalchemy.types import UserDefinedType
from sqlalchemy.sql.expression import BindParameter
from sqlalchemy.ext.compiler import compiles
#================================================
class LiteralBindParam(BindParameter):
pass
@compiles(LiteralBindParam)
def literal_bind(element, compiler, **kw):
kw['literal_binds'] = True
return compiler.visit_bindparam(element, **kw)
#================================================
class ArrayType(UserDefinedType):
def __init__(self, listVal):
self.listVal = listVal
return
def get_col_spec(self):
return "ARRAY"
def literal_processor(self, dialect):
print 'got called'
def process(value):
return 'int_array(' + self.listValue + ')'
return process
#================================================
dbUser = os.environ.get('uid')
dbPwd = os.environ.get('pwd')
oraSID = os.environ.get('sid')
connstr = 'oracle://%s:%s@%s' % (dbUser, dbPwd, oraSID)
#================================================
engine = sqlalchemy.create_engine(connstr)
metadata = MetaData(engine)
Base = declarative_base(metadata=metadata)
sessionMaker = sessionmaker(bind=engine)
session = sessionMaker()
a = LiteralBindParam(None, ArrayType([1,2,3,4,5]))
ret = session.execute(func.some_db_func(a)).scalar()
print ret
----- Original Message -----
From: "Amos Smith" <[email protected]>
To: [email protected]
Sent: Wednesday, February 12, 2014 3:57:40 PM
Subject: Re: [sqlalchemy] array types using OracleDialect
I migrated to 0.9.2 as I understood the literal_processor was new feature.
I always get this error from listing shown below:
def literal_processor(self, dialect):
^
IndentationError: unindent does not match any outer indentation level
ArrayType is obviously just a stub in this listing.
Apologies in advance if this is some obvious Python formatting issue of mine,
I'm still learning this language.
#===== Begin Listing =============================
import os
import sqlalchemy
from sqlalchemy.orm import sessionmaker
from sqlalchemy import MetaData
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import func
from sqlalchemy.types import UserDefinedType
from sqlalchemy.sql.expression import BindParameter
from sqlalchemy.ext.compiler import compiles
#================================================
class LiteralBindParam(BindParameter):
pass
@compiles(LiteralBindParam)
def literal_bind(element, compiler, **kw):
kw['literal_binds'] = True
return compiler.visit_bindparam(element, **kw)
#================================================
class ArrayType(UserDefinedType):
def get_col_spec(self):
return "ARRAY"
def column_expression(self, col):
return None
def literal_processor(self, dialect):
def process(value):
return "int_array(1, 2, 3, 4, 5)"
return process
#================================================
dbUser = os.environ.get('uid')
dbPwd = os.environ.get('pwd')
oraSID = os.environ.get('sid')
connstr = 'oracle://%s:%s@%s' % (dbUser, dbPwd, oraSID)
#================================================
engine = sqlalchemy.create_engine(connstr)
metadata = MetaData(engine)
Base = declarative_base(metadata=metadata)
dialectMgr = DialectManager()
sessionMaker = sessionmaker(bind=engine)
session = sessionMaker()
a = LiteralBindParam(None, ArrayType())
session.execute(func.some_db_func(a)).scalar()
#===== End Listing ===============================
----- Original Message -----
> Regarding the following:
>> if the type of the LiteralBindParameter implements “literal_processor()”,
>> that controls how the literal value is rendered into the statement.
>
> How does one implement the "literal_processor()" for a new type? Is
> literal_processor() method applicable for UserDefinedTypes?
the method is literal_processor:
http://docs.sqlalchemy.org/en/rel_0_9/core/types.html#sqlalchemy.types.TypeEngine.literal_processor
its new as of 0.9 and applies to any type, including UserDefinedType. If you
don’t see it taking effect, that’s a bug.
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