Unity, Using Statement and PerRequestLifetimeManager

Question

I'm using Unity in my project. But I'm unsure whether I should be using the using statement or not as I'm using the PerRequestLifetimeManager.

Simple example:

Injection:

container.RegisterType<IDataContext, MyContext>(new PerRequestLifetimeManager());

Usage:

class MyClass
{
     private readonly IDataContext _context;

     public MyClass(IDataContext context)
     {
           _context = context;
     }

     public string MyMethod()
     {
          // 1. Is this needed?
          using (var u = _context)
          {
               var customers = u.Set<Customer>().OrderBy(o => o.Name);
               // ........
          }

          // 2. OR can I just do this
          var customers = _context.Set<Customer>().OrderBy(o => o.Name);

As I'm using PerRequestLifetimeManager() in my injection, does this negate the requirement of the using statement as the context will be disposed after every http request anyway?

Answer 1

If you would use using then you would immediately dispose DbContext and if you try to access it again it will result in exception, so 1 approach is generally bad idea. 2 would work but what if there would occur problem in DbContext, for instance new data that you would like to persist will be not compliant to db design (for instance indexes). In such case you will be unable to recreate DbContext. My advice would be to register and then resolve factory method for DbContexts:

class MyClass
{
     private readonly Func<IDataContext> _contextFactory;

     public MyClass(Func<IDataContext> contextFactory)
     {
           _contextFactory = contextFactory;
     }

     public string MyMethod()
     {
           // 1. Is this needed?
           using (var u = _contextFactory())
           { 
               var customers = u.Set<Customer>().OrderBy(o => o.Name);
               // ........
           }
     }