Good Practices: DataContexts and BO's
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I've just nearly finished my first LINQ to SQL winforms application, and I'm quite impressed with how the generated BO's work well with DataGridView etc. The application is a simple invoicing application, allowing grid based maintenance of a product list, grid and detail maintenance of customers, and a detail based form for capturing new invoices, with a line items child grid. I'm curious as to good practices for editing single items in details forms, creating new objects etc. First I passed the selected BO to the details form, but then I had changes reflecting immediately in the grid. Now I pass only the BO ID, and use a new DataContext to load another copy of the object in the details form. This way, changes are only persisted when the user invokes a Save command on the details form. To create a new invoice, I create a new Invoice instance and call InsertOnSubmit with it, then I present it for editing, and when done, I call SubmitChanges to insert the invoice.
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I've just nearly finished my first LINQ to SQL winforms application, and I'm quite impressed with how the generated BO's work well with DataGridView etc. The application is a simple invoicing application, allowing grid based maintenance of a product list, grid and detail maintenance of customers, and a detail based form for capturing new invoices, with a line items child grid. I'm curious as to good practices for editing single items in details forms, creating new objects etc. First I passed the selected BO to the details form, but then I had changes reflecting immediately in the grid. Now I pass only the BO ID, and use a new DataContext to load another copy of the object in the details form. This way, changes are only persisted when the user invokes a Save command on the details form. To create a new invoice, I create a new Invoice instance and call InsertOnSubmit with it, then I present it for editing, and when done, I call SubmitChanges to insert the invoice.
Brady, the way you're doing it sounds reasonable. Another approach may be to modify your BO to support a transaction: when your details form opens up, call BO.BeginTransaction. When the user clicks save, commit the transaction. If not, rollback the transaction. I'm sure there are a number of ways to do this. I don't know whether a transaction approach is superior to your BO copy approach.
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