[Grok-dev] Re: 0.14 wishlist items

[Martijn Faassen]

Hi there,

Wichert Akkerman wrote:
[snip]
> Keep in mind that 'data export' as I think you intend it is something
> very different than 'zodb export' other people refer to:
> 
> * ZODB dumps (like the .zexp dumps Zope2 produces) are a full
>   representation of all data in the system. This means it is highly
>   tied to the specific versions of packages you have installed and
>   lots of implementation details. Such a dump is useless for most
>   purposes except backup and restore or moving data between two
>   systems that are completely equivalent.
> 
> * data dumps that contain more 'normal data'. With that I mean things
>   like objects and their data as defined in a schema. This is data
>   that has a well defined structure and can easily be handled by
>   standard tools.

Yes, these are two very different use cases. Thanks for pointing this 
out; I was assuming one from the initial request but it turns out to be 
the other one. :)

The second case is very hard/impossible to do in a completely general 
way. A generic piece of code has only a faint idea what kind of complex 
classes you're using for your application after all, and it doesn't have 
any idea about what would be a nice representation in, say, XML, of this 
same information.

What we could create is the following:

* an infrastructure for exporting and importing content. We could 
consider z3c.vcsync for this. It does much more, but it does contain 
infrastructure for exporting and importing content. Whether it's good 
enough for the generic Grok case, I don't know.

* For schema-driven content, there's z3c.schema2xml which can be used to 
generate an XML representation of content. For anything else, we could 
provide some form of plugin structure so you can define whatever you want.

I don't see it as very realistic to provide an infrastructure that's 
guaranteed to export *everything*, though, without some manual, and 
possibly complicated, work for the application developer.

Regards,

Martijn