warlord at MIT.EDU
Thu Sep 1 20:40:47 EDT 2005
Quoting Mike B <songofmike at yahoo.com>:
> --- Josh Sled <jsled at asynchronous.org> wrote:
>> Account data is primarily organized in the engine's
>> data objects, which
>> are located in src/engine/. The business module
>> compartmentalized into src/business/, and it's
>> "engine"-equivalent is in
> What I'm confused about is how to load/store these
> data objects. We can call this OR mapping or
> serialization. I was under the impression that the
> backend storage could change into an actual relational
Begin_edit/Commit_Edit is first, and then the qof_session_save() is the
second. The former are used in online storage systems (e.g. SQL), the
serialized storage (e.g. XML).
>> What database schema? What SQL queries? What OR
>> mapping layer?
>> GnuCash doesn't have these things, in the same way
>> other systems do.
> Right, so as far as I can tell I need to interface
> with the storage system by using the Query objects.
> It seems like you can build queries of different
> types, and that you build parameters and predicates
> for them. I haven't seen any documentation about how
> this really works, and I'm unclear about how to build
> hese parameters and predicates (or even what is
> possible to build). It's difficult to follow the code
> through several layers of indirection in order to
> discover these things, so I'm asking here. Again, an
> example would really help me. A simple one would be
> getting a list of business customers.
Look in src/business/business-gnome/dialog-customer.c -- at the end of
is sets up the Search Dialog parameter lists for how to search for
customers. If you want a list of ALL customers you could build a query
select * from customers where name matches-regex '.'
The parameters are just what you would think they are, starting with the
QueryFor object. So when you QueryFor Customer, all parameters are based on a
Customer. When you QueryFor Invoice, all parameters are based on an
invoice. So, for example, when searching for an invoice you can search
<invoice>->Owner->Name matches "Company"
The parameter list for this predicate would be Owner, Name, <NULL>. Because
<invoice>->Owner->Name is a string, you need a String predicate to match
against this parameter.
It's all quite logical when you stop reading the code and think of the
architecture. There should even be some rudimentary docs in the source
this, and even in Doxygen.
> - mike
Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
Member, MIT Student Information Processing Board (SIPB)
URL: http://web.mit.edu/warlord/ PP-ASEL-IA N1NWH
warlord at MIT.EDU PGP key available
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