在Startup.cs 中修改ConfigureService() 如下便可:

public void ConfigureServices(IServiceCollection services)
        {
            services.AddMvc().AddJsonOptions(options =>
            {
                options.SerializerSettings.ContractResolver = new CamelCasePropertyNamesContractResolver();
                options.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore;
            }).SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
        }

要解決的話, 只須在DbContext 中Disable 其設定便可.

public class DataContext : DbContext
{
    public DataContext()
    {
        this.Configuration.UseDatabaseNullSemantics = true;
    }
}

參考資料

• DbContextConfiguration.UseDatabaseNullSemantics Property, MSDN, https://msdn.microsoft.com/en-us/library/system.data.entity.infrastructure.dbcontextconfiguration.usedatabasenullsemantics(v=vs.113).aspx

使用時EntityFramework 會直接call SQL server function 並return 其value.

[DbFunction("hkcfDataModel.Store", "GetDonorName")]
public string GetDonorName(string nvchCompanyName, string nvchTcFirstName, string nvchTcLastName, string nvchTcPrefix, string vchEnFirstName, string vchEnLastName, string vchEnPrefix, string vchLang)
{
    throw new NotSupportedException("Direct call does not supported.");
}

 using (NotificationEntities entites = new NotificationEntities())
                {
 entites.EMAILs.Add(email);
                    entites.Database.ExecuteSqlCommand("SET IDENTITY_INSERT [dbo].[EMAIL] ON");
                    entites.SaveChanges();
                    entites.Database.ExecuteSqlCommand("SET IDENTITY_INSERT [dbo].[EMAIL] OFF");
}