Entity Framework Concurrency control using "Timestamp" value check

Question

For concurrency control i Write "VersionCheck" function in my Context class,I need to dynamically load Context object and check if version is the same as the current context object RowVersion. now i use switch statement. (code below) and also, Is there more convenient way for version control?

p.s. RowVersion is TimeStamp type in Database.

  public class SchoolContext : DbContext
  {
    public DbSet<Group> Groups { get; set; }
    public DbSet<Person> Persons { get; set; }

    public bool VersionCheck(string objName)
    {
        var dbc = new SchoolContext();
        byte[] bt1 = null;
        byte[] bt2 = null;

        switch (objName)
        {
            case "Person":
                dbc.Persons.Load();
                bt1 = dbc.Persons.SingleOrDefault(p => p.Id == 1).RowVersion;
                bt2 = this.Persons.Local.SingleOrDefault(p => p.Id == 1).RowVersion;
                break;
            case "Group":
                dbc.Groups.Load();
                bt1 = dbc.Groups.SingleOrDefault(p => p.Id == 1).RowVersion;
                bt2 = this.Groups.Local.SingleOrDefault(p => p.Id == 1).RowVersion;
                break;
        }

        if (bt1 == null && bt2 == null)
        {
            throw new Exception("One of the Variable is null!");
            return true;
        }
        for (int i = 0; i < bt1.Length; i++)
        {
            if (bt1[i] != bt2[i])
            {
                MessageBox.Show("Current object changed!");
                return false;
            }
        }
        return true;
    }

 }

what are you trying to achieve? why do you have 2 separate db context? Are you using the ConcurrencyCheckAttribute for the timestamp or this is a custom solution? If so then what is your goal (again)? — Peter Porfy
– Peter Porfy, Commented Dec 12, 2013 at 14:33
sorry it was my mistake. I edited code. there is only SchoolContext. — sdkarm
– sdkarm, Commented Dec 12, 2013 at 15:12
You have to use optimistic concurrency as described. It is the only way to do the check while updating. Your approach always leaves room for conflicts between the check and the actual update. — Gert Arnold
– Gert Arnold, Commented Dec 12, 2013 at 20:41

Community · Accepted Answer · 2017-05-23 11:49:45Z

1

Optimistic concurrency explained

The described approach looks like data corruption waiting to happen.
Unless you are locking the row or table during the time you read and check the rowversion, then it can change after to you have read it to check its value.

Use Optimistic concurrency paradigm properly.

eg https://stackoverflow.com/a/14718991/1347784

edited May 23, 2017 at 11:49

CommunityBot

11 silver badge

answered Dec 12, 2013 at 14:45

phil soady

11.4k5 gold badges55 silver badges100 bronze badges

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

Collectives™ on Stack Overflow

Entity Framework Concurrency control using "Timestamp" value check

1 Answer 1

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related