Entity Framework

Question

Hi good people. where can find a complete step by step downloadable tutorial on Entity Framework in VB.NET

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John Sot

Answer 1

I doubt you can. Most seem to be in C# and without knowing Entity Framework and reading the tutorials I could not recommend them anyhow in any language as I would not know how good they are. Nor do many of them seem to be downloadable as a .PDF or Word document from what I see.

Perhaps you should ask at StackOverflow where you will need to become a member unless StackOverflow allows MSDN member logons which I doubt. The MSDN Forum for Entity Framework is no longer active and possibly archived.

Also see Entity Framework (EF) Documentation.

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La vida loca

Answer 2

There are no complete step by step guides for Entity Framework online or downloadable. 

There are two camps for Entity Framework, Code First or Model First which variations to both. Then there are versions to contend with e.g. the current flavor is Entity Framework 6 which is being eclipsed by Entity Framework Core.

What I can provide is as follows in regards to Model First (which is a personal choice made by a developer and easier to explain). In the following I'm using one project but generally you would break out EF to a class project.

Create a new windows form project, add new item, under data select ADO.NET Entity Data Model, follow the prompts, from selecting a database table(s) to completion. At one point you will be prompted to provide an name for both the model and entity. Let's say I call my Entity DemoEntities and include a Customer table, no relations to other tables. We get the following (note Navigation properties, if there were relations they are listed here).

To read data we create an instance of the entity and use LINQ or Lambda to read the data. If I wanted all Customers.

Using entity As New DemoEntities
    DataGridView1.DataSource = entity.Customers.ToList
End Using

Sadly the DataGridView is not sortable so we need to use a custom component.

Using entity As New DemoEntities
    DataGridView1.DataSource = New SortableBindingList(Of Customer)(entity.Customers.ToList)
End Using

In short we also want a BindingSource

Using entity As New DemoEntities
    bsCustomers.DataSource = New SortableBindingList(Of Customer)(entity.Customers.ToList)
    DataGridView1.DataSource = bsCustomers
End Using

The BindingSource allows us to get the current item in the DataGridView

Dim LastName As String = CType(bsCustomers.Current, Customer).LastName
Dim Identifier As Integer = CType(bsCustomers.Current, Customer).id
MessageBox.Show($"id: {Identifier} Lastname: {LastName}")

Let's look at an edit for the current row in the DataGridView, we get the current value by casting, set the value, add the item to the context and set it's state follow by saving changes.

Dim customer = CType(bsCustomers.Current, Customer)
customer.FirstName = CType(bsCustomers.Current, Customer).FirstName
Using entity As New DemoEntities
    entity.Entry(customer).State = Data.Entity.EntityState.Modified
    entity.SaveChanges()
End Using

Similarly an add is pretty much the same, delete is slightly different.

I've touch very little here other then the basics. What I have not covered which is huge is validation that is not at form level but instead in the backend and my only public example is in C# on MSDN code sample,

It's a walk in the park for the simple things but can be difficult to grasp when you get into more complex operations, no different then using a managed data provider but I prefer Entity Framework any day.

In closing I recommend a subscription to Plural site and look at the following starting from the top if you want to go code first, if model first then you should still look at her stuff because there is nothing per-say on Model First out there.

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