I am using Microsoft SQL Server 2008 R2 and have three relevant tables: ConvertCarbs, Countries and StateProvinces
Using the EF Power Tools I have Reverse Engineered the Database (http://msdn.microsoft.com/en-us/data/jj593170.aspx) and am trying to insert a record into the ConvertCarb table using the Entity Framework.
But, the program is throwing the following error when trying to save the changes:
Cannot insert explicit value for identity column in table 'ConvertCarb' when IDENTITY_INSERT is set to OFF.
Here is the run time code:
var convertCarb = new ConvertCarb();
convertCarb.CountryID = 150;
db.ConvertCarbs.Add(convertCarb);
db.SaveChanges();
Here are the classes from the domain model:
public partial class ConvertCarb
{
    public int ConvertCarbID { get; set; }
    public Nullable<int> CountryID { get; set; }
    public virtual Country Country { get; set; }
}
public partial class Country
{
    public Country()
    {
        this.ConvertCarbs = new List<ConvertCarb>();
        this.Offices = new List<Office>();
    }
    public int CountryID { get; set; }
    public string CountryName { get; set; }
    public virtual ICollection<ConvertCarb> ConvertCarbs { get; set; }
}
public partial class StateProvince
{
    public StateProvince()
    {
        this.Offices = new List<Office>();
    }
    public int StateProvID { get; set; }
    public string StateProvAbbr { get; set; }
    public virtual ConvertCarb ConvertCarb { get; set; }
    public virtual ICollection<Office> Offices { get; set; }
}
There should be no problem doing this insert since the ConvertCarbID is an Identity Column and I have verified this by running a tsql insert on the database directly.
Here is the create code for the tables in the database:
/****** Object:  Table [dbo].[ConvertCarb]    Script Date: 04/11/2014 03:04:24 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[ConvertCarb](
    [ConvertCarbID] [int] IDENTITY(1,1) NOT NULL,
    [CountryID] [int] NULL,
    [StateProvID] [int] NULL,
    [KWH_FT2] [float] NULL,
    [G_KWH] [decimal](18, 4) NULL,
    [NatGas_GJ_M2] [float] NULL,
    [FuelOil_GJ_M2] [float] NULL,
 CONSTRAINT [PK_ConvertCarb] PRIMARY KEY CLUSTERED 
(
    [ConvertCarbID] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[ConvertCarb]  WITH NOCHECK ADD  CONSTRAINT [FK_ConvertCarb_Countries] FOREIGN KEY([CountryID])
REFERENCES [dbo].[Countries] ([CountryID])
GO
ALTER TABLE [dbo].[ConvertCarb] NOCHECK CONSTRAINT [FK_ConvertCarb_Countries]
GO
ALTER TABLE [dbo].[ConvertCarb]  WITH NOCHECK ADD  CONSTRAINT [FK_ConvertCarb_StateProvinces] FOREIGN KEY([ConvertCarbID])
REFERENCES [dbo].[StateProvinces] ([StateProvID])
GO
ALTER TABLE [dbo].[ConvertCarb] NOCHECK CONSTRAINT [FK_ConvertCarb_StateProvinces]
GO
/****** Object:  Table [dbo].[Countries]    Script Date: 04/11/2014 03:04:12 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[Countries](
    [CountryID] [int] IDENTITY(1,1) NOT NULL,
    [CountryName] [varchar](255) NULL,
 CONSTRAINT [PK_Countries] PRIMARY KEY CLUSTERED 
(
    [CountryID] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
SET ANSI_PADDING OFF
GO
/****** Object:  Table [dbo].[StateProvinces]    Script Date: 04/11/2014 03:05:23 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[StateProvinces](
    [StateProvID] [int] IDENTITY(1,1) NOT NULL,
    [StateProvAbbr] [varchar](2) NULL,
 CONSTRAINT [PK_StateProvinces] PRIMARY KEY CLUSTERED 
(
    [StateProvID] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
SET ANSI_PADDING OFF
GO
Here are the mapping classes generated by the EF tool:
public class ConvertCarbMap : EntityTypeConfiguration<ConvertCarb>
{
    public ConvertCarbMap()
    {
        // Primary Key
        this.HasKey(t => t.ConvertCarbID);
        // Properties
        // Table & Column Mappings
        this.ToTable("ConvertCarb");
        this.Property(t => t.ConvertCarbID).HasColumnName("ConvertCarbID");
        this.Property(t => t.CountryID).HasColumnName("CountryID");
        this.Property(t => t.StateProvID).HasColumnName("StateProvID");
        this.Property(t => t.KWH_FT2).HasColumnName("KWH_FT2");
        this.Property(t => t.G_KWH).HasColumnName("G_KWH");
        this.Property(t => t.NatGas_GJ_M2).HasColumnName("NatGas_GJ_M2");
        this.Property(t => t.FuelOil_GJ_M2).HasColumnName("FuelOil_GJ_M2");
        // Relationships
        this.HasOptional(t => t.Country)
            .WithMany(t => t.ConvertCarbs)
            .HasForeignKey(d => d.CountryID);
        this.HasRequired(t => t.StateProvince)
            .WithOptional(t => t.ConvertCarb);
    }
}
public class CountryMap : EntityTypeConfiguration<Country>
{
    public CountryMap()
    {
        // Primary Key
        this.HasKey(t => t.CountryID);
        // Properties
        this.Property(t => t.CountryName)
            .HasMaxLength(255);
        // Table & Column Mappings
        this.ToTable("Countries");
        this.Property(t => t.CountryID).HasColumnName("CountryID");
        this.Property(t => t.CountryName).HasColumnName("CountryName");
    }
}
public class StateProvinceMap : EntityTypeConfiguration<StateProvince>
{
    public StateProvinceMap()
    {
        // Primary Key
        this.HasKey(t => t.StateProvID);
        // Properties
        this.Property(t => t.StateProvAbbr)
            .HasMaxLength(2);
        // Table & Column Mappings
        this.ToTable("StateProvinces");
        this.Property(t => t.StateProvID).HasColumnName("StateProvID");
        this.Property(t => t.StateProvAbbr).HasColumnName("StateProvAbbr");
    }
}
 
     
     
    