DbUpdateException when removing and saving changes in EF - asp.net-mvc

Question

I'm trying to delete a record in the database by simply using db.'table'.remove('object') but when calling db.SaveChanges() exception is thrown.
'An exception of type 'System.Data.Entity.Infrastructure.DbUpdateException' occurred in EntityFramework.dll but was not handled in user code'
My deleting method in controller
public ActionResult Delete(int? id)
{
if (id == null)
{
return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
}
Customer customer = db.Customers.Find(id);
if (customer == null)
{
return HttpNotFound();
}
db.Customers.Remove(customer);
db.SaveChanges();
return RedirectToAction("Index");
}
Model:
public class Customer
{
[Key, ForeignKey("User")]
public int UserId { get; set; }
public string Email { get; set; }
public virtual CreditCard CreditCard { get; set; }
public virtual ShoppingCart ShoppingCart { get; set; }
public virtual List<Enquiry> Enquiries { get; set; }
public virtual List<Order> Orders { get; set; }
public virtual User User { get; set; }
}
public class User
{
[Key]
public int Id { set; get; }
public string Username { set; get; }
public string Password { set; get; }
public string FirstName { set; get; }
public string Surname { set; get; }
public virtual UserRole UserRole { get; set; }
}
public class ShoppingCart
{
[Key, ForeignKey("Customer")]
public int Id { get; set; }
public virtual List<CartItem> CartItems { get; set; }
public virtual Customer Customer { get; set; }
}
Part of the exception:
A DbUpdateException was caught while saving changes. Type: Customer_8D9A6B7F7D247C9CB9F95E830039791E299E94FC91841FD33610DD1804AEF739 was part of the problem.
Full exception:
System.Data.Entity.Infrastructure.DbUpdateException: An error occurred while updating the entries. See the inner exception for details. ---> System.Data.Entity.Core.UpdateException: An error occurred while updating the entries. See the inner exception for details. ---> System.Data.SqlClient.SqlException: The DELETE statement conflicted with the REFERENCE constraint "FK_dbo.ShoppingCarts_dbo.Customers_Id". The conflict occurred in database "MVC_COMP1562.Models.SchemaDBContext", table "dbo.ShoppingCarts", column 'Id'.
The statement has been terminated.
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, Boolean isInternal, Boolean forDescribeParameterEncryption)
at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async, Int32 timeout, Task& task, Boolean asyncWrite, Boolean inRetry, SqlDataReader ds, Boolean describeParameterEncryptionRequest)
at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, TaskCompletionSource`1 completion, Int32 timeout, Task& task, Boolean& usedCache, Boolean asyncWrite, Boolean inRetry)
at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(TaskCompletionSource`1 completion, String methodName, Boolean sendToPipe, Int32 timeout, Boolean& usedCache, Boolean asyncWrite, Boolean inRetry)
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()
--- End of inner exception stack trace ---
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__35()
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__DisplayClass2a.<SaveChangesInternal>b__27()
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()
--- End of inner exception stack trace ---
at System.Data.Entity.Internal.InternalContext.SaveChanges()
at System.Data.Entity.Internal.LazyInternalContext.SaveChanges()
at System.Data.Entity.DbContext.SaveChanges()
at MVC_COMP1562.Controllers.CustomersController.Delete(Nullable`1 id) in C:\Users\kacpe\Documents\Visual Studio 2015\Projects\MVC_COMP1562\MVC_COMP1562\Controllers\CustomersController.cs:line 165

Answer 1

It seems you have another Table called dbo.ShoppingCarts about a Shopping Cart, which have one or more rows related to the Customer you are trying to delete.
So first you must delete the rows related to that customer an then you can delete the customer. That happens because the Customer id is foreign key in that other table.
If that is no exactly the case, please add your ShoppingCarts class to the question.