I want to override the default value of a column in the table A, where B is a child of A.
On Fri, Jun 29, 2018 at 4:29 PM, Mike Bayer <[email protected]> wrote: > On Fri, Jun 29, 2018 at 4:20 PM, Marcus Mann <[email protected]> wrote: > > And why do you use the doc property in > > data = column_property(A.data, doc="B's data") > > and why do you change A.data in class B? > > well you said you wanted a "description", which I am still unclear > what you mean by that, "doc" is used to assign a docstring to a column > attribute. It places it in __doc__ and shows up in Sphinx > doumentation, for example. Then you said you wanted to override it > on B so I re-wrapped it. > > I'm not sure that's what you want now, your example looks more like > you want the value of the attribute to be fixed on the subclass, but > persisted on the superclass? i don't see how that would work yet. > > > > > > On Fri, Jun 29, 2018 at 4:18 PM, Mike Bayer <[email protected]> > > wrote: > >> > >> a Column is a Core schema construct that is not part of the ORM. The > >> ORM maps a Column to your mapped class using a column_property() that > >> wraps around it. When you use declarative_base, the declarative > >> system is automatically generating these column_property() objects for > >> each Column you have by itself. > >> > >> On Fri, Jun 29, 2018 at 4:16 PM, Marcus Mann <[email protected]> > wrote: > >> > I guess I am still a little confused about the relationship between > >> > Column > >> > and column_property > >> > > >> > On Fri, Jun 29, 2018 at 4:14 PM, Mike Bayer <[email protected] > > > >> > wrote: > >> >> > >> >> On Fri, Jun 29, 2018 at 11:46 AM, Marcus Mann <[email protected]> > >> >> wrote: > >> >> > When I said description, I just meant a simple string that > describes > >> >> > the > >> >> > object, not a python docstring. Just an example column. > >> >> > >> >> so....does my example answer your question? > >> >> > >> >> > >> >> > >> >> > >> >> > > >> >> > On Friday, June 29, 2018 at 9:49:07 AM UTC-4, Mike Bayer wrote: > >> >> >> > >> >> >> your question is getting no answers because it is vague and > doesn't > >> >> >> provide any code. what's a "description"? you mean a Python > >> >> >> docstring ? Python attributes don't have a __doc__ normally, if > >> >> >> you > >> >> >> mean the "doc" parameter, just make a separate property: > >> >> >> > >> >> >> class A(Base): > >> >> >> __tablename__ = 'a' > >> >> >> > >> >> >> id = Column(Integer, primary_key=True) > >> >> >> > >> >> >> data = column_property(Column(String), doc="the data") > >> >> >> > >> >> >> > >> >> >> class B(A): > >> >> >> __tablename__ = 'b' > >> >> >> > >> >> >> id = Column(ForeignKey('a.id'), primary_key=True) > >> >> >> > >> >> >> data = column_property(A.data, doc="B's data") > >> >> >> > >> >> >> > >> >> >> > >> >> >> > >> >> >> On Fri, Jun 29, 2018 at 8:41 AM, Marcus Mann <[email protected]> > >> >> >> wrote: > >> >> >> > > >> >> >> > > >> >> >> > > >> >> >> > https://stackoverflow.com/questions/51046900/how-to- > access-override-defaults-on-parents-attribute-in-sql-alchemy > >> >> >> > > >> >> >> > -- > >> >> >> > SQLAlchemy - > >> >> >> > The Python SQL Toolkit and Object Relational Mapper > >> >> >> > > >> >> >> > http://www.sqlalchemy.org/ > >> >> >> > > >> >> >> > To post example code, please provide an MCVE: Minimal, Complete, > >> >> >> > and > >> >> >> > Verifiable Example. See http://stackoverflow.com/help/mcve for > a > >> >> >> > full > >> >> >> > description. > >> >> >> > --- > >> >> >> > 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]. > >> >> >> > To post to this group, send email to [email protected]. > >> >> >> > Visit this group at https://groups.google.com/group/sqlalchemy. > >> >> >> > For more options, visit https://groups.google.com/d/optout. > >> >> > > >> >> > -- > >> >> > SQLAlchemy - > >> >> > The Python SQL Toolkit and Object Relational Mapper > >> >> > > >> >> > http://www.sqlalchemy.org/ > >> >> > > >> >> > To post example code, please provide an MCVE: Minimal, Complete, > and > >> >> > Verifiable Example. See http://stackoverflow.com/help/mcve for a > full > >> >> > description. > >> >> > --- > >> >> > 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]. > >> >> > To post to this group, send email to [email protected]. > >> >> > Visit this group at https://groups.google.com/group/sqlalchemy. > >> >> > For more options, visit https://groups.google.com/d/optout. > >> >> > >> >> -- > >> >> SQLAlchemy - > >> >> The Python SQL Toolkit and Object Relational Mapper > >> >> > >> >> http://www.sqlalchemy.org/ > >> >> > >> >> To post example code, please provide an MCVE: Minimal, Complete, and > >> >> Verifiable Example. See http://stackoverflow.com/help/mcve for a > full > >> >> description. > >> >> --- > >> >> 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]. > >> >> To post to this group, send email to [email protected]. > >> >> Visit this group at https://groups.google.com/group/sqlalchemy. > >> >> For more options, visit https://groups.google.com/d/optout. > >> > > >> > > >> > -- > >> > SQLAlchemy - > >> > The Python SQL Toolkit and Object Relational Mapper > >> > > >> > http://www.sqlalchemy.org/ > >> > > >> > To post example code, please provide an MCVE: Minimal, Complete, and > >> > Verifiable Example. See http://stackoverflow.com/help/mcve for a full > >> > description. > >> > --- > >> > 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]. > >> > To post to this group, send email to [email protected]. > >> > Visit this group at https://groups.google.com/group/sqlalchemy. > >> > For more options, visit https://groups.google.com/d/optout. > >> > >> -- > >> SQLAlchemy - > >> The Python SQL Toolkit and Object Relational Mapper > >> > >> http://www.sqlalchemy.org/ > >> > >> To post example code, please provide an MCVE: Minimal, Complete, and > >> Verifiable Example. See http://stackoverflow.com/help/mcve for a full > >> description. > >> --- > >> 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]. > >> To post to this group, send email to [email protected]. > >> Visit this group at https://groups.google.com/group/sqlalchemy. > >> For more options, visit https://groups.google.com/d/optout. > > > > > > -- > > SQLAlchemy - > > The Python SQL Toolkit and Object Relational Mapper > > > > http://www.sqlalchemy.org/ > > > > To post example code, please provide an MCVE: Minimal, Complete, and > > Verifiable Example. See http://stackoverflow.com/help/mcve for a full > > description. > > --- > > 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]. > > To post to this group, send email to [email protected]. > > Visit this group at https://groups.google.com/group/sqlalchemy. > > For more options, visit https://groups.google.com/d/optout. > > -- > SQLAlchemy - > The Python SQL Toolkit and Object Relational Mapper > > http://www.sqlalchemy.org/ > > To post example code, please provide an MCVE: Minimal, Complete, and > Verifiable Example. See http://stackoverflow.com/help/mcve for a full > description. > --- > 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]. > To post to this group, send email to [email protected]. > Visit this group at https://groups.google.com/group/sqlalchemy. > For more options, visit https://groups.google.com/d/optout. > -- SQLAlchemy - The Python SQL Toolkit and Object Relational Mapper http://www.sqlalchemy.org/ To post example code, please provide an MCVE: Minimal, Complete, and Verifiable Example. See http://stackoverflow.com/help/mcve for a full description. --- 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]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
