一首诗 schrieb: > I'm very glad to know that turbojson could automatic convert > SQLAlchemy object to JSON. But unfortunately, it can not handle SA > object circuit. > > For example, there are 2 of SA mapped class, User and Role. User has > more than 1 role and a role could be given to many user. This is a > very common M:N relationship in relational database. > > But turbojson can not convert an instance of User to JSON > automatically, because there is a reference loop. What now we can do > is add a "__json__" method to manually convert an object json, which > is very tedious. > > So my suggestion is : why not just skipped there objects referenced > more than one time? This will be a behavior easily undertood and will > save a lot of time writing "__json__".
There are two big problems with this: - JSON has no concept of refernces, it's a purely algrebraic structure. As a consequence, you can't serialize graph-structures with it. So you need to come up with a special key/value pair that denotes a reference. This is purely to your own design. - if that behavior would be default, it would mean that e.g. returning a user in facebook would return all his 4000 friends. Which is a rather dumb thing to do if all you want is a user's primary attributes, don't you agree? So I'm afraid this can't be implemented the way you wish. I'm not sure how this is dealt with in TG2, but in TG1 it was very easy to declare a special rendering for specific objects, based on rules dispatch. You should try & do that. Diez --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "TurboGears" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/turbogears?hl=en -~----------~----~----~----~------~----~------~--~---
