Is the general case that a context typically lasts as long as the
transaction, gets discarded, and a new one is created for the next
transaction or is it dependent on usage in the program? For example, a
web app as discussed here discards contexts based on user interactions
while a thick client app would tend to reuse the same context.
Just curious...
Garth
On 11/07/2012 12:51 AM, Aristedes Maniatis wrote:
On 7/11/12 4:57pm, Alexey Katorgin wrote:
You should always create a context and then create objects within
that context
using the methods Cayenne
gives you. This is different to the undecorated POJO that Hibernate
allows you
to create.
Ari
I develop a web-app and if I will create entities bounded to a
dataContext, and
after user has leaved the page (by browser navigation buttons,
closing the tab,
etc.) such entities will stay uncommitted and may be in inconsistency
state
(user has not filled all required fields). And on the next commit
this objects
will be committed and raise validation exception.
It is the reason why I want to use unbounded dataObjects.
So I've decide to use transient objects not bounded to any
dataContext. In this
case such object just be removed by garbage collector after user
leaved page
unexpectedly. And where user will click OK, such objects will be
manually
attached to a dataContext and committed.
It makes my code less clearly if can't set relationships between
transient
objects. Because I need to create additional temporary lists to store
all
transient entities and iterate its to register to a dataContext before
committing.
What is the best practice for this use case?
Typically you bind a context to the user session so that the user can
continue to navigate through the site and not lose the work they have
done but not yet saved. For example, they may assemble a shopping
basket, contact details and payment information. Then you commit the
whole thing atomically at the end.
Don't think of a data context as something you create when you are
ready to save. Think of it as a big bucket into which you put all the
objects you are working with. At the end, throw it away and make a new
one, or commit it to the database. For more complex arrangements read
up on how to create parent/child contexts, but you don't need to do
that here. Start simple.
Make as many contexts as you need to have buckets of different
information.
Ari
