Re: [sqlalchemy] Redefine class on runtime
Also there's a long term plan to remove classical mappings as a first class feature, replacing it with an equivalent function that applies declarative mapping to a class.There isn't a plan to have a "clear_mappers()" in this case, the way you clear a mapping for a class is that you stop using that class and allow it to be garbage collected. If your class happens to be referred to by a superclass which sees it as one of the inheriting mappers it might have to load, there's no plan to support surgical removal of that subclass.So you'd want to stop using the superclass as well. This all points to the recommended way to do this, which is to just use declarative normally and if you need a different kind of class / table def inside of a polymorphic inheritance hierarchy for the same name, you build out a new polymorphic inheritance hierarchy and throw the old one away. mapper.dispose() is not going to alter the polymorphic collection of the superclass either. Supporting the surgical removal of specific mappers from an existing mapper hierarchy adds a huge amount of complexity, testing, and development effort to every new mapping feature that associates mappers together, which is why we don't support this use case. On Tue, Mar 5, 2019 at 8:54 AM Mike Bayer wrote: > > The individual mapper clear process is via the mapper.dispose() > method. The individual class that was mapped will be de-instrumented > and act like a regular Python class. > > The next steps to take depend very highly on what kind of mappings you > are using and what you are trying to do. > > > On Tue, Mar 5, 2019 at 2:00 AM Tolstov Sergey wrote: > > > > Thanks for answer, can i get only part of classes mappers? Somethink about > > Myclass.mapper.clear()? > > > > -- > > 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 sqlalchemy+unsubscr...@googlegroups.com. > > To post to this group, send email to sqlalchemy@googlegroups.com. > > 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 sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at https://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
Re: [sqlalchemy] Redefine class on runtime
The individual mapper clear process is via the mapper.dispose() method. The individual class that was mapped will be de-instrumented and act like a regular Python class. The next steps to take depend very highly on what kind of mappings you are using and what you are trying to do. On Tue, Mar 5, 2019 at 2:00 AM Tolstov Sergey wrote: > > Thanks for answer, can i get only part of classes mappers? Somethink about > Myclass.mapper.clear()? > > -- > 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 sqlalchemy+unsubscr...@googlegroups.com. > To post to this group, send email to sqlalchemy@googlegroups.com. > 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 sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at https://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
Re: [sqlalchemy] Redefine class on runtime
Thanks for answer, can i get only part of classes mappers? Somethink about Myclass.mapper.clear()? -- 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 sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at https://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
Re: [sqlalchemy] Redefine class on runtime
On Mon, Mar 4, 2019 at 12:40 AM Tolstov Sergey wrote: > > Hi, for unit tests i need to create class with Base.metadata.create_all, and > delete table defintion (for tests) > > On second definition i have a error (already defined) > > With use Base.metadata.clear i get warning > > SAWarning: Reassigning polymorphic association for identity 'testparentclass' > from to 0x7f910d83f860; TestParentClass>: Check for duplicate use of > 'testparentclass' as value for polymorphic_identity. > > Can i clear cached inherit? metadata.create_all / drop_all aren't related to the state of your mappers, these two methods can be called freely with no need to call metadata.clear(). You likely should not be using metadata.clear(). If OTOH you are actually changing the structure of declarative classes per test such that something is being removed from a mapping, you would need to use clear_mappers() and redefine all classes and mappings from scratch, using a new Base.You can't remove elements from mappings, such as here where you'd want to remove a polymorphic subclass and replace it with a new one. If you are using classical mappings or hybrid delcarative mappings with __table__, there might be some more options here but it's usually best to keep class hierarchies that are local to tests fully within the setup/teardown of those tests. > > -- > 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 sqlalchemy+unsubscr...@googlegroups.com. > To post to this group, send email to sqlalchemy@googlegroups.com. > 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 sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at https://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
