将 Entity Framework 6 项目分层

Question

I am going through a tutorial on Entity Framework 6 and trying to implement this into a test project. This would be targeting ASP.Net webforms but i think the principle would be the same for MVC projects.

I have 3 projects DAL, BAL and Webforms project.

I create a Class Library called DAL, Install EF 6. Add ADO.Net Entity Data Model, link to the database. This has 2 tables for ease Customer and Addresses. The connection string is stored in the app.config file.

Table 1 (Customers)- Id, Firstname, Surname
Table 2 (Addresses)- Id, PrimaryAddress, CustomerId

1. I see a.tt file and expanding it i see all the classes resembling my database tables. If i want to add another method ie

   Public string GetCustomerFullName { return Firstname + " " + Surname; }

Where and how would i do this on the DAL project? I was thinking of the Class created when expanding the.tt file (ie Customer class) but i have a sneaky feeling this may get overridden if i was to regenerate /refresh some part of the ADO.Net Entity Data Model file, eg if a table is added or something?

2. I create another Class Library called BAL (this is where i would like to call all of the CRUD operations). Install EF6 from Nuget. I add reference to the DAL project. Currently the tutorial adds a new Dbcontext instance for every method ie Add, Update etc within the same project.

How do i reference the DbContext created in DAL project in this project? I've read a mixture of threads that a new context could give odd behaviour where others feel reusing the same context is/not a good idea. Could someone show me how to reference the DbContext in the correct way. I normally have an abstract class which is then added to my classes eg

    public class CustomerService : DbContxtService, ICustomer
    {
     public void Add(Customer c)
    {
    // Add customer
    }
    }

3. How could set the DAL project to retrieve the connection string from my Web forms project (so that i dont need to always change the Class Library and could have one area to change the connection string)

Answer 1

If i want to add another method.. where would I do it.

The entity definitions are partial classes . You can add members to the class in a separate file that wouldn't be overwritten.

How do i reference the DbContext created in DAL project in this project?

You set a reference to the project and add a constructor dependency for each service on your (single) DbContext.

eg

public class CustomerService 
{
    private MyDbContext db;
    public CustomerService(MyDbContext db)
    {
       this.db = db;
    {
    public void CreateNewCustomer(Customer c)
    {
       //CRUD and business logic here
       ...
       db.SaveChanges();
    }
    public Customer GetCustomerWithHistory(int customerId)
    {
       db.Customer.Include("SalesOrders").FirstOrDefault( c => c.Id = customerId);
    }

    public void CreateCustomerServiceTicket(Customer c, Incident i)
    {
    }
}

Note this should be a business service, not a repository.