On Feb 7, 2011, at 11:42 AM, Martijn Moeling wrote: > I think, I might be helped with the create_instance "event"
Assuming you're talking about when the ORM establishes an instance from a newly fetched row, you can use the @reconstructor hook for that. 0.7 publishes this event additionally as the "load" event. > > I will never ever stop a class from being saved/persistent, > > it is the other way around. I thought I was able to use joins and or > relations to limit for "allowed" results from a query. > With all the polymorphic and self references I have got and the fact that I > need to do so for multiple Polymorphic colums I came up with the ACL idea. > > Im not sure it if will perform, but in the create_instance I will look up the > ACL and set additional properties on the instance or create an empty one. > > This whole system is getting very complex now and limiting returned data > involves modifying relationsships a lot. I'm really glad I got that working. > > Many classes are base on top of that and I the only IT guy working on this > together with "programmers" with a chemistry degree. Who will need the API I > am working on to do their stuff without knowing anything about > Databases........ > > To have that I Inherit polymorphicly, have many-to-many self references, use > mixins. > > I'll have a look at the PreFilteredQuery example you gave me, Any thoughts > are helpful, I'll see If I can make up an example with persons and addresses > again since the molecule stuff makes it even more confusing.. > Will take me some time though > > Martijn > > > > > On Feb 7, 2011, at 5:18 PM, Michael Bayer wrote: > >> >> On Feb 7, 2011, at 10:55 AM, Martijn Moeling wrote: >> >>> Hi, >>> >>> It is me again with an interesting thing, I've searched the net, this group >>> etc. Not a lot of people seem interested in append_result, I AM!! >>> >>> I am looking for a way to implement the following: >>> >>> >>> I have many tables, a lot with polymorphic inheritance and self and cross >>> references. >>> >>> In order to control "available" data I have set up a system similar to ACL >>> (Access Control Lists) >>> >>> Depending on "Who I am" I can get data from the database. >>> >>> I want to do so within the MapperExtension I already have set up to do some >>> "before update" and "before insert" >> >> Limitations on inserts, updates and queries are best done outside of the >> Mapper. By the time the mapper is dealing with instructions to persist or >> load a row, its usually too late, unless you're looking to raise an >> exception upon certain conditions. For example there's no way to >> "stop" the insert from happening inside of a "before insert" operation, >> short of raising an exception (maybe that's what you're doing). >> >> A SessionExtension.before_flush() OTOH allows you to modify everything >> that's going to happen before any flush plans are made. >> >> Regarding append_result(), its a very old hook from 0.1 that's never had any >> real use. In this case I would instead be ensure that the undesired rows >> are not in the result set to start with. The recipe at >> http://www.sqlalchemy.org/trac/wiki/UsageRecipes/PreFilteredQuery is a >> decent starting point for such a recipe. >> >> >>> >>> >>> def append_result(self, mapper, selectcontext, row, instance, result, >>> **flags): >>> if instance.__tablename__ == 'he': >>> return EXT_STOP >>> else: >>> return EXT_CONTINUE >>> >>> would do such a thing, but I want (for the sake of the code behind that) to >>> continue with a heavily modified instance. >>> >>> To avoid making this long code (a lot of different object types pass >>> through here, remember the polymorhic bit) >>> >>> Does anyone have an interesting approach to this? basically I need to do >>> something like instance= instance_class_type(new, configuration, based, on, >>> the, ACL) >>> >>> >>> >>> Any help would be wonderfull, >>> >>> Martijn >>> >>> >>> >>> >>> >>> >>> >>> >>> -- >>> 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 >>> sqlalchemy+unsubscr...@googlegroups.com. >>> For more options, visit this group at >>> http://groups.google.com/group/sqlalchemy?hl=en. >>> >> >> -- >> 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 >> sqlalchemy+unsubscr...@googlegroups.com. >> For more options, visit this group at >> http://groups.google.com/group/sqlalchemy?hl=en. >> > > -- > 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 > sqlalchemy+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/sqlalchemy?hl=en. > -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. 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