[sqlalchemy] Re: Dynamically adding MapperExtension
I think I came up with a decent solution for this: I do something like: extension = MyMapperExtension() for mapper in mapper_registry.values(): mapper.extension = extension mapper._compile_extensions() If you want all classes currently defined in the metadata to map to your new extension. This is actually working quite well. cheers. chris On Feb 9, 11:33 am, Michael Bayer [EMAIL PROTECTED] wrote: I should add that you *can* be more creative, and construct each mapper with aMapperExtensionat the beginning which later can be enabled with a hello world callable. i.e. class MyExt(MapperExtension): def __init__(self): self.func = None def after_insert(self, ...): if self.func: self.func() extension = MyExt() mapper(foo, bar, extension=extension) mapper(foo2, bar2, extension=extension) mapper(foo3, bar3, extension=extension) ... do stuff ... def helloworld(): print hello world extension.func = helloworld ... do stuff ... percious wrote: question. Lets say I have a series of table definitions, and a series of objects linked to the tables with a bunch of mappers. First question: Is there a way to get from the table definitions in the metadata to the Mapper? Second question: If I create aMapperExtension, can I then link it to the mapper associated with a table? What I want to do is create a simple application that goes through the tables defined within a metadata, and create an extension so that every time a table entry is added it prints 'hello world' to the screen. TIA -chris --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] Re: Dynamically adding MapperExtension
percious wrote: question. Lets say I have a series of table definitions, and a series of objects linked to the tables with a bunch of mappers. First question: Is there a way to get from the table definitions in the metadata to the Mapper? not conveniently. you could loop through the dictionary of mappers in sqlalchemy.orm.mapperlib.mapper_registry and just look at all the mapped_table attributes of those mappers. or just track yourself. Second question: If I create a MapperExtension, can I then link it to the mapper associated with a table? MapperExtensions currently like to be set at the time of mapper construction. there is also a way to say query.options(extension(someext)), but theres a pending ticket which is needed for some fixes to that...also that only sets an extension that takes place within the realm of a select. What I want to do is create a simple application that goes through the tables defined within a metadata, and create an extension so that every time a table entry is added it prints 'hello world' to the screen. yah that pattern is not really supported. tables/mappers/etc like to be constructed and then not changed after that, so if you cant apply your hello world function at table/mapper construction time, the closest thing you could do is either use a customized logging stream to trap INSERT statements, or if you used DynamicMetaData you could have it connect() to a ProxyEngine instance which does similar. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] Re: Dynamically adding MapperExtension
question. Lets say I have a series of table definitions, and a series of objects linked to the tables with a bunch of mappers. First question: Is there a way to get from the table definitions in the metadata to the Mapper? For simple table==class, the link is 1:1. For multi-table-inheritances/ single-inheritances, it's many:1. And the linking is mostly the other way (mapper-to-tables, not tables-to-mappers), so u may have to dig: u can use either m=class_mapper( yourclas) or m=object_mapper( obj); then check isinstance( m.localtable, Table), and use it... all mappers are in mapper_registry... but this is all pure gymnastics... Second question: If I create a MapperExtension, can I then link it to the mapper associated with a table? themapper.extension = yours... ; or see global_extensions. dontknow about their compilation though... What I want to do is create a simple application that goes through the tables defined within a metadata, and create an extension so that every time a table entry is added it prints 'hello world' to the screen. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] Re: Dynamically adding MapperExtension
I should add that you *can* be more creative, and construct each mapper with a MapperExtension at the beginning which later can be enabled with a hello world callable. i.e. class MyExt(MapperExtension): def __init__(self): self.func = None def after_insert(self, ...): if self.func: self.func() extension = MyExt() mapper(foo, bar, extension=extension) mapper(foo2, bar2, extension=extension) mapper(foo3, bar3, extension=extension) ... do stuff ... def helloworld(): print hello world extension.func = helloworld ... do stuff ... percious wrote: question. Lets say I have a series of table definitions, and a series of objects linked to the tables with a bunch of mappers. First question: Is there a way to get from the table definitions in the metadata to the Mapper? Second question: If I create a MapperExtension, can I then link it to the mapper associated with a table? What I want to do is create a simple application that goes through the tables defined within a metadata, and create an extension so that every time a table entry is added it prints 'hello world' to the screen. TIA -chris --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
