Re: [sqlalchemy] table inheritance: how to change a record from base type to derived type?
On Tue, Dec 10, 2013 at 3:54 PM, Michael Bayer mike...@zzzcomputing.comwrote: On Dec 10, 2013, at 5:04 PM, Iain Duncan iainduncanli...@gmail.com wrote: Hi, I'm stuck on how to do something that I'm sure must be possible. I have two kinds of records, using table inheritance, Client, and SpecialClient. SpecialClient has extra fields and it's own polymorphic identity. I need to *promote* a and existing client record to a special client. I tried just making a SpecialClient and copying over attributes, but this is giving me can't set attribute error messages. Can anyone tell me what the *right* way to do change a polymorphic type, while keeping it's ID the same, would be? In my case, the ID in the derived type is an fkey to the base type table's id col. if its joined inheritance, you have to INSERT into the new table manually, that feature isn’t supported right now. if it’s single, try emitting an UPDATE for the “discriminator” column, then reloading the object. I think it's joined inheritance? The derived table's primarky key is an id column that is also an fkey to the base table's id column and the base table has a _type column holding the poly id. Does this mean I should drop into sql directly to create the record in the derived table and it will just work? thanks Michael! iain Thanks! Iain -- 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 sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/groups/opt_out. -- 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 sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/groups/opt_out.
Re: [sqlalchemy] table inheritance: how to change a record from base type to derived type?
On Dec 11, 2013, at 12:45 PM, Iain Duncan iainduncanli...@gmail.com wrote: On Tue, Dec 10, 2013 at 3:54 PM, Michael Bayer mike...@zzzcomputing.com wrote: On Dec 10, 2013, at 5:04 PM, Iain Duncan iainduncanli...@gmail.com wrote: Hi, I'm stuck on how to do something that I'm sure must be possible. I have two kinds of records, using table inheritance, Client, and SpecialClient. SpecialClient has extra fields and it's own polymorphic identity. I need to *promote* a and existing client record to a special client. I tried just making a SpecialClient and copying over attributes, but this is giving me can't set attribute error messages. Can anyone tell me what the *right* way to do change a polymorphic type, while keeping it's ID the same, would be? In my case, the ID in the derived type is an fkey to the base type table's id col. if its joined inheritance, you have to INSERT into the new table manually, that feature isn’t supported right now. if it’s single, try emitting an UPDATE for the “discriminator” column, then reloading the object. I think it's joined inheritance? The derived table's primarky key is an id column that is also an fkey to the base table's id column and the base table has a _type column holding the poly id. Does this mean I should drop into sql directly to create the record in the derived table and it will just work”? you need to manipulate the tables directly, and then totally reload the original object fresh. pretty much make the ORM think the previous Client never existed. signature.asc Description: Message signed with OpenPGP using GPGMail
[sqlalchemy] table inheritance: how to change a record from base type to derived type?
Hi, I'm stuck on how to do something that I'm sure must be possible. I have two kinds of records, using table inheritance, Client, and SpecialClient. SpecialClient has extra fields and it's own polymorphic identity. I need to *promote* a and existing client record to a special client. I tried just making a SpecialClient and copying over attributes, but this is giving me can't set attribute error messages. Can anyone tell me what the *right* way to do change a polymorphic type, while keeping it's ID the same, would be? In my case, the ID in the derived type is an fkey to the base type table's id col. Thanks! Iain -- 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 sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/groups/opt_out.
Re: [sqlalchemy] table inheritance: how to change a record from base type to derived type?
On Dec 10, 2013, at 5:04 PM, Iain Duncan iainduncanli...@gmail.com wrote: Hi, I'm stuck on how to do something that I'm sure must be possible. I have two kinds of records, using table inheritance, Client, and SpecialClient. SpecialClient has extra fields and it's own polymorphic identity. I need to *promote* a and existing client record to a special client. I tried just making a SpecialClient and copying over attributes, but this is giving me can't set attribute error messages. Can anyone tell me what the *right* way to do change a polymorphic type, while keeping it's ID the same, would be? In my case, the ID in the derived type is an fkey to the base type table's id col. if its joined inheritance, you have to INSERT into the new table manually, that feature isn’t supported right now. if it’s single, try emitting an UPDATE for the “discriminator” column, then reloading the object. Thanks! Iain -- 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 sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/groups/opt_out. signature.asc Description: Message signed with OpenPGP using GPGMail
[sqlalchemy] table inheritance
Hey,
I have a declarative table called 'Foo':
_Base = declarative_base()
class Foo(_Base):
__tablename__ = 'foo'
__table_args__ = {'mysql_engine': 'InnoDB',
'mysql_charset': 'latin1'}
id = Column(String(64), primary_key=True, autoincrement=False)
stuff = Column(Integer(11), primary_key=True, nullable=False)
Now I create Foo1 that has exactly the same definition but differs
just by the name:
class Foo1(_Base):
__tablename__ = 'foo1'
__table_args__ = {'mysql_engine': 'InnoDB',
'mysql_charset': 'latin1'}
id = Column(String(64), primary_key=True, autoincrement=False)
stuff = Column(Integer(11), primary_key=True, nullable=False)
And I need more of those (FooN with N = 10). The use case is to shard
data across several tables.
To avoid cut/n/pastes, I tried inheritance, meta-class, a type
factory and the like, but everything fails. Whether because I was
reusing the same column class objects or whether because I was
conflicting with SQLALchemy meta-class magic.
Is there any sane way to do this and avoid a crazy copy/paste ?
Cheers
Tarek
--
Tarek Ziadé | http://ziade.org
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Re: [sqlalchemy] table inheritance
This is the entity name recipe, and we have a classical and declarative
version over at http://www.sqlalchemy.org/trac/wiki/UsageRecipes/EntityName .
It's using just the straight type() factory.
You definitely want to use distinct Column objects for each class, this because
a Column object is immediately made to reference its parent Table, for obvious
reasons. Recipes that generate multiple tables from a single set of Column
objects use the copy() method on Column for this purpose. However, you don't
even need to deal with that, since declarative mixins take care of the copy()
stuff for you. I've updated the EntityName example to illustrate taking
advantage of the mixin so check it out.
On Dec 7, 2010, at 10:45 AM, Tarek Ziadé wrote:
Hey,
I have a declarative table called 'Foo':
_Base = declarative_base()
class Foo(_Base):
__tablename__ = 'foo'
__table_args__ = {'mysql_engine': 'InnoDB',
'mysql_charset': 'latin1'}
id = Column(String(64), primary_key=True, autoincrement=False)
stuff = Column(Integer(11), primary_key=True, nullable=False)
Now I create Foo1 that has exactly the same definition but differs
just by the name:
class Foo1(_Base):
__tablename__ = 'foo1'
__table_args__ = {'mysql_engine': 'InnoDB',
'mysql_charset': 'latin1'}
id = Column(String(64), primary_key=True, autoincrement=False)
stuff = Column(Integer(11), primary_key=True, nullable=False)
And I need more of those (FooN with N = 10). The use case is to shard
data across several tables.
To avoid cut/n/pastes, I tried inheritance, meta-class, a type
factory and the like, but everything fails. Whether because I was
reusing the same column class objects or whether because I was
conflicting with SQLALchemy meta-class magic.
Is there any sane way to do this and avoid a crazy copy/paste ?
Cheers
Tarek
--
Tarek Ziadé | http://ziade.org
--
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Re: [sqlalchemy] table inheritance
On Tue, Dec 7, 2010 at 5:08 PM, Michael Bayer mike...@zzzcomputing.com wrote: This is the entity name recipe, and we have a classical and declarative version over at http://www.sqlalchemy.org/trac/wiki/UsageRecipes/EntityName . It's using just the straight type() factory. You definitely want to use distinct Column objects for each class, this because a Column object is immediately made to reference its parent Table, for obvious reasons. Recipes that generate multiple tables from a single set of Column objects use the copy() method on Column for this purpose. However, you don't even need to deal with that, since declarative mixins take care of the copy() stuff for you. I've updated the EntityName example to illustrate taking advantage of the mixin so check it out. Thanks ! I am always amazed by how fast and accurately you are always answering here, kudos for this. Cheers Tarek -- Tarek Ziadé | http://ziade.org -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
[sqlalchemy] Table Inheritance
Please refer to the Joined Table Inheritance Section under declarative.ext (I'm using SA 0.5.8). Is is possible to create a Person who is both an Engineer and a Manager using joined table inheritance? IOW, both Manager and Engineer would link to the same row in Person. Thanks, Mark -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
