Entity Framework Code First with Repository Pattern and lazy loading?

Question

Consider the following simple example:

public class Employee
{
    public int Id { get; set; }
    public string Name { get; set; }
    ... other employee properties ...
    public virtual ICollection<Sale> Sales { get; set; } 
}

public class Sale
{
    public int Id { get; set; }
    public int EmployeeId { get; set; }
    public DateTime DateSold { get; set; }
    ... other sale properties ...
    public virtual Employee Employee { get; set; }
}

public class SampleContext: DbContext
{
    public DbSet<Employee> Employees { get; set; }
    public DbSet<Sale> Sales { get; set; }
}

I create a repository that uses the above entity framework context to return employees by id:

public interface IRepository
{
    Employee EmployeeById(int id);
}

My question is in regards to populating and returning employee sales. In the vast majority of use cases, the code requesting a particular person only needs the sales for a given day. How should I handle that? Do I extend the Employee class to some EmployeeWithDailySales object?

I can't use lazy loading in the calling function as the DbContext reference does not exist once I return from the repository class. Does that mean I am doing something incorrect to begin with? Is my idea of the repository itself flawed?

I could preload the employee's sales when I initially populate the Employee object but that would likely result in many unneeded records in most situations.

Any advice is greatly appreciated. I am still trying to get a clear understanding of how to use these patterns and frameworks correctly.

Be.St. · Accepted Answer · 2012-01-20 14:37:39Z

1

First of all I suggest you use the session-per-request pattern to handle DbContext.

In Application_BeginRequest method instantiate the DbContext and allow accessing it from your controllers.

In Application_EndRequest dispose/close your DbContext.

Then I think that "requesting a particular person only needs the sales for a given day" is a business rule you must put in a service.

So add a service like EmployeeService to manage your Employee class. Add a method like

Employee GetByDate(DateTime salesDay)

where you load Employee and Sales data for that given date.

You have to inject DbContext also in the EmployeeService.

answered Jan 20, 2012 at 14:37

Be.St.

4,1813 gold badges28 silver badges36 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Entity Framework Code First with Repository Pattern and lazy loading?

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related