using LINQ update particular column in asp.net mvc 3

Question

I have following code for updating user's column

 public void UpdateLastModifiedDate(string username)
        {
            using (AppEntities db = new AppEntities())
            {
                var result = from u in db.Users where (u.UserName == username) select u;

                if (result.Count() != 0)
                {
                    var dbuser = result.First();

                    dbuser.LastModifiedDate = DateTime.Now;
                    db.SaveChanges();
                }
            }
        }

I have other's 2 function of almost same of above function for UpdateLastLogOutDate, UpdateLastLoginDate. So, I decided to define single function for all to update Last Date like:

public void UpdateLastDate(string username, string ColumnName);

Here, I can not put ColumnName variable like this:

dbuser.ColumnName = DateTime.Now;

Is there any other way to do this using LINQ

Darin Dimitrov · Accepted Answer · 2012-06-21 08:05:29Z

6

You could define the method like this:

public void Update(string username, Action<User> action)
{
    using (AppEntities db = new AppEntities())
    {
        var result = from u in db.Users where (u.UserName == username) select u;

        if (result.Count() != 0)
        {
            var dbuser = result.First();
            action(dbuser);
            db.SaveChanges();
        }
    }
}

And now there could be different usages of this method:

Update("john", user => user.LastModifiedDate = DateTime.Now);                
Update("smith", user => user.UpdateLastLogOutDate = DateTime.Now);
Update("admin", user => 
{
    user.LastModifiedDate = DateTime.Now;
    user.UpdateLastLogOutDate = DateTime.Now;
});

But if the expression is not known at compile time you may take a look at dynamic LINQ.

answered Jun 21, 2012 at 8:05

Darin Dimitrov

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1 Comment

CodeManiac Over a year ago

Thanks a lot I have tried it and works perfectly. It helps me to reduce a lot of code. Thanks again

Jay · Accepted Answer · 2012-10-11 01:09:10Z

1

You could write your code this way also by sending an instance of your entity as parameter:

public void UpdateLastModifiedDate(Entityclassname ent) //[like if table name is item then Entityclassname should be items etc..]
{   
  using (AppEntities db = new AppEntities())            
  {      
    var result = from u in db.Users where (u.UserName == ent.username) select u;   
    if (result.Count() != 0)         
      {                   
           var dbuser = result.First();        
             dbuser.LastModifiedDate = DateTime.Now; 
             dbuser.UpdateLastLogOutDate=ent.UpdateLastLogOutDate ;
             db.SaveChanges();    
      }
  } 
}

edited Oct 11, 2012 at 1:09

Jay

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answered Oct 11, 2012 at 1:02

sinjini chatterjee

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