Editing an object in Entity Framework 6 - asp.net-mvc

Question

I have an object Employee containing lots of information on an Employee, such as his Login, Name, LastName, e-mail address etc.
After retrieving all the information imputed on the edit page of an employee, I then call the following to update the object :
public Employee Edit(Employee objEmployee) // Work on EDIT
{
var Original = Get(objEmployee.Login);
_entities.Employees.Add(objEmployee);
_entities.SaveChanges();
return objEmployee;
}
Once it reaches SaveChanges() I get the following :
System.Data.Entity.Infrastructure.DbUpdateException was caught
HResult=-2146233087
Message=An error occurred while updating the entries. See the inner exception for details.
Source=EntityFramework
StackTrace:
at System.Data.Entity.Internal.InternalContext.SaveChanges()
at System.Data.Entity.Internal.LazyInternalContext.SaveChanges()
at System.Data.Entity.DbContext.SaveChanges()
at CRAWebSiteMVC.Models.EntityEmployeeManagerRepository.Edit(Employee objEmployee) in c:\Users\kade\Source\Workspaces\InfoCubedProjects\CRA\CRAWebSiteMVC\Models\Employee\EntityEmployeeManagerRepository.cs:line 26
at CRAWebSiteMVC.Models.EmployeeManagerService.Edit(Employee objEmployee) in c:\Users\kade\Source\Workspaces\InfoCubedProjects\CRA\CRAWebSiteMVC\Models\Employee\EmployeeManagerService.cs:line 113
InnerException: System.Data.Entity.Core.UpdateException
HResult=-2146233087
Message=An error occurred while updating the entries. See the inner exception for details.
Source=EntityFramework
StackTrace:
at System.Data.Entity.Core.Mapping.Update.Internal.UpdateTranslator.Update()
at System.Data.Entity.Core.EntityClient.Internal.EntityAdapter.<Update>b__2(UpdateTranslator ut)
at System.Data.Entity.Core.EntityClient.Internal.EntityAdapter.Update[T](T noChangesResult, Func`2 updateFunction)
at System.Data.Entity.Core.EntityClient.Internal.EntityAdapter.Update()
at System.Data.Entity.Core.Objects.ObjectContext.<SaveChangesToStore>b__d()
at System.Data.Entity.Core.Objects.ObjectContext.ExecuteInTransaction[T](Func`1 func, IDbExecutionStrategy executionStrategy, Boolean startLocalTransaction, Boolean releaseConnectionOnSuccess)
at System.Data.Entity.Core.Objects.ObjectContext.SaveChangesToStore(SaveOptions options, IDbExecutionStrategy executionStrategy, Boolean startLocalTransaction)
at System.Data.Entity.Core.Objects.ObjectContext.<>c__DisplayClassb.<SaveChangesInternal>b__8()
at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute[TResult](Func`1 operation)
at System.Data.Entity.Core.Objects.ObjectContext.SaveChangesInternal(SaveOptions options, Boolean executeInExistingTransaction)
at System.Data.Entity.Core.Objects.ObjectContext.SaveChanges(SaveOptions options)
at System.Data.Entity.Internal.InternalContext.SaveChanges()
InnerException: System.Data.SqlClient.SqlException
HResult=-2146232060
Message=Violation of PRIMARY KEY constraint 'PK_EMPLOYEE'. Cannot insert duplicate key in object 'dbo.Employee'.
The statement has been terminated.
Source=.Net SqlClient Data Provider
ErrorCode=-2146232060
Class=14
LineNumber=1
Number=2627
Procedure=""
Server=MMSDEVNEW\SQL2008
State=1
StackTrace:
at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose)
at System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady)
at System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString)
at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async, Int32 timeout, Task& task, Boolean asyncWrite, SqlDataReader ds)
at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, TaskCompletionSource`1 completion, Int32 timeout, Task& task, Boolean asyncWrite)
at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(TaskCompletionSource`1 completion, String methodName, Boolean sendToPipe, Int32 timeout, Boolean asyncWrite)
at System.Data.SqlClient.SqlCommand.ExecuteNonQuery()
at System.Data.Entity.Infrastructure.Interception.DbCommandDispatcher.<NonQuery>b__0(DbCommand t, DbCommandInterceptionContext`1 c)
at System.Data.Entity.Infrastructure.Interception.InternalDispatcher`1.Dispatch[TTarget,TInterceptionContext,TResult](TTarget target, Func`3 operation, TInterceptionContext interceptionContext, Action`3 executing, Action`3 executed)
at System.Data.Entity.Infrastructure.Interception.DbCommandDispatcher.NonQuery(DbCommand command, DbCommandInterceptionContext interceptionContext)
at System.Data.Entity.Internal.InterceptableDbCommand.ExecuteNonQuery()
at System.Data.Entity.Core.Mapping.Update.Internal.DynamicUpdateCommand.Execute(Dictionary`2 identifierValues, List`1 generatedValues)
at System.Data.Entity.Core.Mapping.Update.Internal.UpdateTranslator.Update()
InnerException:
Violation of PRIMARY KEY constraint 'PK_EMPLOYEE'. Cannot insert duplicate key in object 'dbo.Employee'.
What could be causing that, and how may I solve it?

Answer 1

You need to update the entity and not to re-insert it:
public Employee Edit(Employee objEmployee) // Work on EDIT
{
_entities.Employees.Attach(objEmployee);
var entity = _entities.Entry(objEmployee);
entry.State = EntityState.Modified; // Mark as modified
_entities.SaveChanges();
return objEmployee;
}