如何扩展实体框架6模型

我正在尝试扩展一个EF6代码优先的模型，但遇到了一个错误。我已经搜索过了，找不到太多关于这个问题的信息。我在同一个命名空间中创建了一个与我的模型同名的分部类。这是我的型号和扩展名：

型号-

namespace DataAccess.Models
{
    using System;
    using System.Collections.Generic;
    using System.ComponentModel.DataAnnotations;
    using System.ComponentModel.DataAnnotations.Schema;
    using System.Data.Entity.Spatial;
    [Table("Vehicle")]
    public partial class Vehicle
    {
        public Vehicle()
        {
            WorkOrders = new HashSet<WorkOrder>();
        }
        public int VehicleID { get; set; }
        public int CustomerID { get; set; }
        [StringLength(17)]
        public string VIN { get; set; }
        public int Mileage { get; set; }
        [StringLength(4)]
        public string Year { get; set; }
        [StringLength(50)]
        public string Make { get; set; }
        [StringLength(50)]
        public string Model { get; set; }
        [StringLength(50)]
        public string Engine { get; set; }
        [StringLength(50)]
        public string BodyStyle { get; set; }
        [StringLength(50)]
        public string Transmission { get; set; }
        [StringLength(50)]
        public string Trim { get; set; }
        [StringLength(50)]
        public string Origin { get; set; }
        public bool IsDeleted { get; set; }
        [StringLength(25)]
        public string License { get; set; }
        public bool? Is4WD { get; set; }
        [StringLength(25)]
        public string Color { get; set; }
        public string Notes { get; set; }
        [StringLength(2)]
        public string LicenseState { get; set; }
        public virtual Customer Customer { get; set; }
        public virtual ICollection<WorkOrder> WorkOrders { get; set; }
    }
}

扩展-

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace DataAccess.Models
{
    public partial class Vehicle
    {
        public string CustomerName { get; set; }
    }
}

我得到的错误是：

｛"自数据库已创建。考虑使用代码优先迁移进行更新数据库(http://go.microsoft.com/fwlink/?LinkId=238269)。"｝

尝试调用存储过程时出现此错误。更具体地说，它被扔到了这条线上：

using (ObjectContext objectContext = ((System.Data.Entity.Infrastructure.IObjectContextAdapter)dbContext).ObjectContext)

这种方法的

public List<Vehicle> SearchVehicles(string vin,
                                            string license,
                                            string year,
                                            string make,
                                            string model)
        {
            SqlParameter vinParameter;
            if (vin != null)
            {
                vinParameter = new SqlParameter("vin", vin);
            }
            else
            {
                vinParameter = new SqlParameter("vin", "");
            }
            SqlParameter licenseParameter;
            if (license != null)
            {
                licenseParameter = new SqlParameter("license", license);
            }
            else
            {
                licenseParameter = new SqlParameter("license", "");
            }
            SqlParameter yearParameter;
            if (year != null)
            {
                yearParameter = new SqlParameter("year", year);
            }
            else
            {
                yearParameter = new SqlParameter("year", "");
            }
            SqlParameter makeParameter;
            if (make != null)
            {
                makeParameter = new SqlParameter("make", make);
            }
            else
            {
                makeParameter = new SqlParameter("make", "");
            }
            SqlParameter modelParameter;
            if (model != null)
            {
                modelParameter = new SqlParameter("model", model);
            }
            else
            {
                modelParameter = new SqlParameter("model", "");
            }
            using (AiContext dbContext = new AiContext())
            {
                using (ObjectContext objectContext = ((System.Data.Entity.Infrastructure.IObjectContextAdapter)dbContext).ObjectContext)
                {
                    return objectContext.ExecuteStoreQuery<Vehicle>("SearchVehicles  @VIN, " +
                                                                    "@License, @Year, " +
                                                                    "@Make, @Model",
                                                                    vinParameter,
                                                                    licenseParameter,
                                                                    yearParameter,
                                                                    makeParameter,
                                                                    modelParameter).ToList();
                }
            }
        }

我熟悉这个错误。EF显然认为我已经对模型进行了更改，并希望我更新数据库。关于我为什么会出现这个错误，或者用其他方法扩展模型以添加属性或业务逻辑，有什么想法吗？感谢您提前提供的帮助。

[NotMapped]
public string CustomerName { get; set; }