Lets take an example of WinForms applcation and making invoice. On the Invoice form we retrieve a list of products, so the user will be ale to pick products for current invoice. Lets also consider that during this process user realizes that he needs to add a new product (or edit current) to ProductList before he can place it in invoice. So he opens a ProductForm where all the products are retreived (again).
It could also be in opposite order, that user first edits Products, and then without closing the Products Form, opens new Invoice. The principle is that data is two times loaded, and effectively its the same data.
What is the propper way to handle this scenario, so we can tell one form that data is already loaded, and to retrieve that data from memory? And when all the consumers (Forms) of the data are closed, then also the data should be released from memory? Or I am going in wrong direction, and there is a better way?
Thanks,
Goran
Definitelly go with data loaded “twice” or you will introduce much worse problems.
Sharing data means sharing ObjectContext. Even in WinForms application this is considered as bad approach. Check this article (it is about NHibernate but the description is valid for EF as well).
The problem is that ObjectContext is unit of work. If share context between two windows you can easily get into situation where you modify data in first window (without saving them!) and you continue in second window where you push save button but it will save data from both windows! You can’t selectively save data only from one window when you share the context.