Hey All,
I'm having an issue finding a best-practice approach for CRUD operations
with FDS. Create/Read/Delete are easy, I'm having a problem with
updates.
I can easily encapsulate CRD's in my Commands, but there doesn't seem to
be an option to explicitly commit only a single record with FDS.
In a non-cairngorm application, this is pretty easy, I can create a
record, then call ds.createItem(), update it and then ds.commit(). The
DataService object is local to the interface that is managing the
record. No problem, one record committed (correct?).
However, with Cairngorm:
1. Get a list of records
a. dispatch ProductEvent.GET_ALL
b. GetAllProductsCommand.execute()
c. ds = new DataService("productHome");
d. ds.fill(model.products);
2. Edit a product
a. myList.dataProvider = model.products
b. dispatch ProductEvent.EDIT, event.product =
myList.selectedItem
c. interface changes to the product form
d. make modifications via a form
e. dispatch ProductEvent.SAVE, event.product =
myform.product
f. SaveProductCommand.execute()
g. ds = new DataService("productHome");
h. ...... how do we commit just this one record?
Even if I still had a reference to the original DataService from the
fill operation, I may not want to commit all records that changed, only
the one that I'm interested in. This would be equivalent to keeping my
DataService in my ServiceLocator.
The only other option I can think of is that SaveProductCommand works
like this, which messes up conflict checks:
1. product = (event as ProductEvent).product;
2. ds = new DataService("productHome");
3. ds.getItem({product_id: product.product_id});
4. locally synchronize the item retrieved from ds.getItem() with
the product we received in the product event
5. ds.commit()
When we do this though, we very likely have the most recent copy of the
object from the database, so we're not sure that something hadn't
changed before getting it.
Am I making this too complex? Is there another way to simply commit one
particular record? I can think of all sorts of workarounds, but all of
them violate the Cairngorm protocols. I can definitely see the other
developers on the team bypassing our Command logic making Cairngorm a
little useless :-)
Jay Proulx
Application Developer
Internet Delivery Services - eVision Team
[EMAIL PROTECTED]
(613) 783-6711
