Proper way to use dbcontext (Global or pass as parameter?)

Question

When I call a method that need dbcontext for update or insert but only want one saveChange() like following

Action: Login

        TempDBEntity context = new TempDBEntity();
        var temp = context.Users.Where(m => m.user_unique_id == 1).FirstOrDefault();
        temp.timestamp = new DateTime();
        temp.AddLog("Login");
        context.SaveChanges();

Function: AddLog

public void AddLog(string activity){
        TempDBEntity context2 = new TempDBEntity();
        var log = new UserLog();
        log.user_id = this.user_id;
        log.activity = activity;
        context2.UserLog.Add(log);
        context2.SaveChanges();
 }

As you can see, there is double SaveChanges() which I only need 1 SaveChanges().

Should I pass DBContext as another parameter for AddLog() or should I declare static variable for dbcontextin this case?

Thanks a lot.

Answer 1

In your case i would create a new dabtase context in the method you need it, because this is the easiest way and you can reuse your methods very good.

This should not make a lot of performance problems, because entity framework cache all important information over the database context, so creating a new one is very fast.

If you want optimize the amount of transactions, than i would write a kind of handler, which implements it's own SaveChanges method and hold one databse context per instance. Than you have one more abstraction layer and a nice API for later use.

Here is a simple example:

class UserLogin
{
    private TempDBEntity dbContex;

    UserLogin()
    {
        // ctor create dbContext
    }

    void Login()
    {
        // Login...
    }

    void AddLog()
    {
        // ...
    }

    void SaveChanges()
    {
        //dbContext.SaveChanges()...
    }
}

Passing a dbcontext as parameter is in my point of view not a very good solution. But this is opinion based...

Answer 2

You can use the dbcontext as follows:

Action: Login

using(TempDBEntity context = new TempDBEntity())
{
   var temp = context.Users.Where(m => m.user_unique_id == 1).FirstOrDefault();
   temp.timestamp = new DateTime();
   temp.AddLog("Login", context);
}

Function: AddLog

public void AddLog(string activity, TempDBEntity context)
{
    var log = new UserLog();
    log.user_id = this.user_id;
    log.activity = activity;
    context.UserLog.Add(log);
    context.SaveChanges(); 
}

This will properly dispose the object after its use.