Can I update my employee record as given in the function below or do I have to make a query of the employee collection first and then update the data?
public int updateEmployee(App3_EMPLOYEE employee)
{
DBContextDataContext db = new DBContextDataContext();
db.App3_EMPLOYEEs.Attach(employee);
db.SubmitChanges();
return employee.PKEY;
}
Or do I have to do the following?
public int updateEmployee(App3_EMPLOYEE employee)
{
DBContextDataContext db = new DBContextDataContext();
App3_EMPLOYEE emp = db.App3_EMPLOYEEs.Single(e => e.PKEY == employee.PKEY);
db.App3_EMPLOYEEs.Attach(employee,emp);
db.SubmitChanges();
return employee.PKEY;
}
But I don't want to use the second option. Is there any efficient way to update data?
I am getting this error by using both ways:
An attempt has been made to Attach or Add an entity that is not new, perhaps having been loaded from another DataContext. This is not supported.
I find following work around to this problem :
1) fetch and update entity (I am going to use this way because it's ok for me )
public int updateEmployee(App3_EMPLOYEE employee)
{
AppEmployeeDataContext db = new AppEmployeeDataContext();
App3_EMPLOYEE emp = db.App3_EMPLOYEEs.Single(e => e.PKEY == employee.PKEY);
emp.FIRSTNAME = employee.FIRSTNAME;//copy property one by one
db.SubmitChanges();
return employee.PKEY;
}
2) disable ObjectTrackingEnabled as following
// but in this case lazy loading is not supported
public AppEmployeeDataContext() :
base(global::LinqLibrary.Properties.Settings.Default.AppConnect3DBConnectionString, mappingSource)
{
this.ObjectTrackingEnabled = false;
OnCreated();
}
3) Detach all the related objects
partial class App3_EMPLOYEE
{
public void Detach()
{
this._APP3_EMPLOYEE_EXTs = default(EntityRef<APP3_EMPLOYEE_EXT>);
}
}
public int updateEmployee(App3_EMPLOYEE employee)
{
AppEmployeeDataContext db = new AppEmployeeDataContext();
employee.Detach();
db.App3_EMPLOYEEs.Attach(employee,true);
db.SubmitChanges();
return employee.PKEY;
}
4) use Time stamp in the column
http://www.west-wind.com/weblog/posts/135659.aspx
5) Create stored procedure for updating your data and call it by db context