Getting ObjectContext error even after calling ToList - entity-framework

Question

When calling the method directly below I get a ObjectDisposedException when calling Mapper.Map with the retrieved list.
System.ObjectDisposedException: The ObjectContext instance has been disposed and can no longer be used for operations that require a connection.
public IEnumerable<Models.Provider> Get(string owner)
{
List<Data.Models.Provider> providers;
using (var db = new Data.ProviderDirectoryContext())
{
providers = db.Providers.Where(p => p.Owner.Name == owner).ToList();
}
var dtoProviders = Mapper.Map<List<Data.Models.Provider>, List<Models.Provider>>(providers);
return dtoProviders;
}
I previously had the code like this (below), I wasn't getting an error, but the database was getting pounded when doing the mapping, and it was taking too long. I don't want to hit the database, when doing the mapping.
public IEnumerable<Models.Provider> Get(string owner)
{
using (var db = new Data.ProviderDirectoryContext())
{
var providers = db.Providers.Where(p => p.Owner.Name == owner).ToList();
var dtoProviders = Mapper.Map<List<Data.Models.Provider>, List<Models.Provider>>(providers);
return dtoProviders;
}
}
How can I retrieve all the data before doing the mapping?
Here is the DbContext and the Data.Models.Provider for your reference.
public class ProviderDirectoryContext : DbContext
{
public DbSet<Owner> Owners { get; set; }
public DbSet<Location> Locations { get; set; }
public DbSet<LocationAuditLog> LocationAuditLog { get; set; }
public DbSet<Office> Offices { get; set; }
public DbSet<OfficePhoneNumber> OfficePhoneNumbers { get; set; }
public DbSet<OfficeAuditLog> OfficeAuditLog { get; set; }
public DbSet<OfficeDay> OfficeDays { get; set; }
public DbSet<Provider> Providers { get; set; }
public DbSet<ProviderPhoneNumber> ProviderPhoneNumbers { get; set; }
public DbSet<ProviderAuditLog> ProviderAuditLog { get; set; }
public DbSet<ProviderType> ProviderTypes { get; set; }
public DbSet<ProviderSpecialty> ProviderSpecialties { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
modelBuilder.Entity<Provider>().HasRequired(cn => cn.Owner).WithMany().WillCascadeOnDelete(false);
modelBuilder.Entity<Office>().HasRequired(cn => cn.Owner).WithMany().WillCascadeOnDelete(false);
}
}
public class Provider
{
public int Id { get; set; }
public int OwnerId { get; set; }
public virtual Owner Owner { get; set; }
public int? ProviderTypeId { get; set; }
public virtual ProviderType ProviderType { get; set; }
public int? ProviderSpecialtyId { get; set; }
public virtual ProviderSpecialty ProviderSpecialty { get; set; }
[Required]
[StringLength(75)]
public string FirstName { get; set; }
[StringLength(75)]
public string MiddleName { get; set; }
[Required]
[StringLength(75)]
public string LastName { get; set; }
[StringLength(100)]
public string EmailAddress { get; set; }
public virtual ICollection<ProviderPhoneNumber> PhoneNumbers { get; set; }
public string Note { get; set; }
public DateTime? InactiveOn { get; set; }
public int OfficeId { get; set; }
public virtual Office Office { get; set; }
public virtual ICollection<ProviderAuditLog> AuditLog { get; set; }
[Required]
public DateTime CreatedOn { get; set; }
[Required]
[StringLength(75)]
public string CreatedBy { get; set; }
[Required]
public DateTime ModifiedOn { get; set; }
[Required]
[StringLength(75)]
public string ModifiedBy { get; set; }
}
Thanks for the help!

Answer 1

The problem is that the Models.Provider class contains other classes like Models.Office, and Models.PhoneNumbers that were not eagerly loaded by the query. In addition to that, the Models.Provider class needs to be flattened. The Mapper wants to recursively map everything, and it keeps going down to the next class. For example, Provider.Office.Location.Offices.
The solution is to flatten Models.Provider and add .Include() to the query so it eagerly loads the data required.
I'll clean this up a bit more, but this is currently working.
public IEnumerable<Models.Provider> Get(string owner)
{
List<Data.Models.Provider> providers;
using (var db = new Data.ProviderDirectoryContext())
{
providers = db.Providers
.Where(p => p.Owner.Name == owner)
.Include("ProviderType")
.Include("ProviderSpecialty")
.Include("Office")
.Include("PhoneNumbers")
.ToList();
}
var dtoProviders = Mapper.Map<List<Data.Models.Provider>, List<Models.Provider>>(providers);
return dtoProviders;
}
public class Provider
{
public int Id { get; set; }
public int OwnerId { get; set; }
public int OfficeId { get; set; }
public string OfficeName { get; set; }
public int? ProviderTypeId { get; set; }
public string ProviderTypeName { get; set; }
public int? ProviderSpecialtyId { get; set; }
public string ProviderSpecialtyName { get; set; }
public string FirstName { get; set; }
public string MiddleName { get; set; }
public string LastName { get; set; }
public string EmailAddress { get; set; }
public virtual ICollection<PhoneNumber> PhoneNumbers { get; set; }
public string Note { get; set; }
public DateTime? InactiveOn { get; set; }
public DateTime CreatedOn { get; set; }
public string CreatedBy { get; set; }
public DateTime ModifiedOn { get; set; }
public string ModifiedBy { get; set; }
}

Answer 2

I am not sure how much this will help with performance but declaring the variable you don't want to dispose outside the using statement should fix your dispose exception.
public IEnumerable<Models.Provider> Get(string owner)
{
IEnumerable<Models.Provider> dtoProviders;
using (var db = new Data.ProviderDirectoryContext())
{
List<Data.Models.Provider> providers = db.Providers.Where(p => p.Owner.Name == owner).ToList();
dtoProviders = Mapper.Map<List<Data.Models.Provider>, List<Models.Provider>>(providers);
}
return dtoProviders;
}