DataBinding to class objects

[chris van duin]

I've split my solution into business layer (class objects), data layer (SQL specific), and UI layer (forms and user controls). I can add a datasource for my class objects within the main project but I can't do the same at my UI level where I need it.

I have an openning form in my main project which I can drag and drop the datasource objects to the form with no problem. However, I need this functionality in my UI form objects which are contained in a seperate project (.dll) which I reference in my main project.

When I try to add a datasource at my UI level I get the following problem: I select Object as my datasource and then select next. I get the following error: An unexpected error has occurred - Error Message: Object reference not set to and instance of an object.

Any ideas?

 

[jmcilhinney]

You can't use the designer to bind business objects. You need to do it in code. Your DAL retrieves the data and pass it to your BLL in a DataTable. Your BLL creates a business object for each row in the table, adds then all to a collection and passes that to your PL. Your PL then binds that collection to the controls, e.g.

Me.BindingSource1.DataSource = Me.businessLogicManager.GetWidgets()
Me.DataGridView1.DataSource = Me.BindingSource1

businessLogicManager is a class in your BLL that manages your business rules. GetWidgets is a method that gets a DataTable full of Widget records from the DAL, packages that data into a collection of Widget objects and returns it. That way you get your DataGridView bound to a collection of Widget objects, which is what you want.