Is it possible to create 0-code (trivial) app using data binding and Entity Framework? How?

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+1 Q:

Is it possible to create 0-code (trivial) app using data binding and Entity Framework? How?

I tried following the steps I describe below in VS 2010, but to no avail:

Create new Windows Forms App. Project
Add new empty ADO EDM to Project
Add new entity Customer with scalar properties FirstName and LastName
Generate db script
Execute db script to create tables in db
Add new Object Data Source based on EDM Model1
Select object Customer in Data Sources window and drop it on form in form of Details view.
All typical binding controls are created, all I need to do is to enable the Save button.

I run the app, form is displayed. I can add new records and navigate between them. I press save, but when I reinitialize the app, all data is lost.

Is it possible to make this work with 0 code, if not, what is the minimum I should add to make this work.

+2 A:

Thomas Levesque 2009-08-16 00:28:32

What db file do you refer to exactly? My EDM points to database in Sql Server and I would expect changes to be persisted to DB ie. new records should be visible as data in a table in a database.

Dan 2009-08-16 01:16:43

OK, you're not using an attached .mdf file ?

Thomas Levesque 2009-08-16 02:13:08

see my updated answer

Thomas Levesque 2009-08-16 02:17:30

Only after adding following code am I able to persist to DB. However, binding is still not working since data is not loaded initially. *** Public Class Form1 Dim ctx As Model1Container = New Model1Container() Private Sub CustomerBindingNavigatorSaveItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles CustomerBindingNavigatorSaveItem.Click Dim c = Customer.CreateCustomer(IdTextBox.Text, FirstNameTextBox.Text, LastNameTextBox.Text) ctx.Customers.AddObject(c) ctx.SaveChanges() End Sub End Class ***

Dan 2009-08-16 04:01:25

You need to set the BindingSource's DataSource property to an instance of the entity set : `customerBindingSource.DataSource = ctx.Customers;`

Thomas Levesque 2009-08-16 13:54:32

Even after setting the DataSource, the code is still flawed. It will work only if I press Save after adding each new item. If I add 3 in a row and press Save it will not work. **Could you by any chance post the whole code for this trivial example?**

Dan 2009-08-16 17:11:35

See my updated answer for the link

Thomas Levesque 2009-08-16 18:18:24

Hi Thomas. Thanks for going through all this trouble. I added another line to CustomerBindingNavigatorSaveItem_Click event handler: CustomerBindingSource.MoveFirst(). It seems that binding is not aware of the value you entered into the control until the control loses focus. I was getting NULL value exceptions from the DB on insert and that fixed the problem. I got a feeling VS 2010 is still quirky; it’s beta so I guess it’s understandable.

Dan 2009-08-16 23:04:37

By default the binding updates the source when the control is validated (which happens, for instance, when it looses focus). You can change the properties of the bindings so that the source is immediately updated (PropertyChanged)

Thomas Levesque 2009-08-16 23:15:32

ansaurus

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Is it possible to create 0-code (trivial) app using data binding and Entity Framework? How?

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