包括来自不同 DbContext 的模型

Question

我不确定如何实现 2 个 DbContext 之间的关系。 PurchaseOrderDbContext 是一种代码优先的方法，而 AgencyDbContext 是一个现有的数据库。如何根据 PurchaseOrder DivisionId 包含来自 AgencyDbContext 的“部门”？

从这里开始是我的代码的一个非常简化的版本。

采购订单模型

   namespace Website.Models.PurchaseOrders
  {
    public class PurchaseOrder
    {
    public int ID { get; set; }
    public DateTime OrderDate { get; set; } 
    public string Name { get; set; }     
    public int DivisionId { get; set; }
    public int StatusID { get; set; }    
    public Agency.Division Division { get; set; }
    } 
  }

划分模型（这是在不同的 DbContext 中）

    namespace Website.Models.Agency
{
    public class Division
    {
            public int DivisionId { get; set; }
            public string DivisionName { get; set; }
            public string DivisionShortName { get; set; }
            public string DivisionAbbrev { get; set; }
            public int? DivisionDirectorEmpId { get; set; }

    }
}

Agency DbContext

    namespace Website.Models.Agency
{
    public class AgencyDbContext : DbContext
    {


        public Agency DbContext(DbContextOptions<AgencyDbContext> options) : base(options)
        {

        }

        public virtual DbSet<Division> Division { get; set; }
        public virtual DbSet<Section> Section { get; set; }


        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {

        }
    }
}

PurchaseOrderDbContext

  namespace Website.Models.PurchaseOrders
{
    public class PurchaseOrderDbContext : DbContext
    {

        public PurchaseOrderDbContext(DbContextOptions<PurchaseOrderDbContext> options) : base(options)
        {}
        public DbSet<Status> Statuses { get; set; }
        public DbSet<PurchaseOrder> PurchaseOrder { get; set; }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
        }

    }

    }

我收到错误 InvalidOperationException：在 Include 中使用的 Lambda 表达式无效。这是指 Division 上的 Include 扩展。

                 var purchaseOrder = _context.PurchaseOrder
                                    .Include(p => p.Division)
                                    .Include(p => p.Status)
                                    .OrderByDescending(p => p.OrderDate);

提前谢谢你！

Answer 1

解决问题的唯一方法可能是在第一个上下文中查询您要查找的项目，然后使用来自第二个上下文的条目填充 Division 属性

public class PurchaseOrderService
{
    private readonly PurchaseOrderDbContext purchaseOrderDbContext;
    private readonly AgencyDbContext agencyDbContext;

    public PurchaseOrderService(PurchaseOrderDbContext purchaseOrderDbContext,
        AgencyDbContext agencyDbContext)
    {
        this.purchaseOrderDbContext = purchaseOrderDbContext;
        this.agencyDbContext = agencyDbContext;
    }

    public PurchaseOrder Get(int id)
    {
        var purchaseOrder = purchaseOrderDbContext.PurchaseOrder.FirstOrDefault(x => x.ID == id);

        if (purchaseOrder == null)
        {
            return null;
        }

        purchaseOrder.Division = agencyDbContext.Division.FirstOrDefault(x => x.DivisionId == purchaseOrder.DivisionId);

        return purchaseOrder;
    }
}