asp.net-mvc - 多个 DbContexts 不同的数据库

Question

我是 EF Code First 的新手，几周来一直很喜欢它。我面临着处理 2 个数据库(都在同一个 Sqlserver 中)。第一个数据库包含一个表，我只需要引用它的主键，它与我创建的表“逻辑上”相关(第二个 DbContext -- 第二个数据库)。基于这个键，我将查询我的第二个 DbContext 表(mvc 站点的实际相关表)。顺便说一下，Customer 有 0..* 个 CustomerUsers。

第一个数据库上下文:

public class Customer
{

    [StringLength(10, MinimumLength = 3), Required]
    public string CompanyID { get; set; }

    [StringLength(8, MinimumLength = 3)]
    [DatabaseGenerated(DatabaseGeneratedOption.None)]
    public string CustomerID { get; set; }


    [StringLength(500)]
    public string CustomerName { get; set; }


    //*Initially, under the same dbContext, they were related, but now am separating
    //them because of physical database separation; hence the navigation property   
    //public virtual ICollection<CustomerUser> CustomerUsers { get; set; }

}

在 OnModelCreating 方法中:

modelBuilder.Entity<Customer>()
            .HasKey(c => new { c.CompanyID, c.CustomerID});

“逻辑上”相关的实体

public class CustomerUser
{

    [Display(Name = "Customer ID")]
    public int CustomerUserID { get; set; }

    //[ForeignKey("Customer")]
    [Display(Name = "CompanyID"), Required]
    [StringLength(10, MinimumLength = 3)]
    public string CompanyID { get; set; }

    //[ForeignKey("Customer")]
    [Display(Name = "CustomerID"), Required]
    [StringLength(8, MinimumLength = 3)]
    public string CustomerID { get; set; }


    [StringLength(50), Display(Name = "First Name"), Required]
    public string FirstName { get; set; }

    [StringLength(50), Display(Name = "Last Name"), Required]
    public string LastName { get; set; }

    //*Initially related thru foreign key to Customer but separation of database
    //thus no more relations – just a querying of Customer’s id from other database
    //public virtual Customer Customer { get; set; }


}

OnModelCreating方法:

modelBuilder.Entity<CustomerUser>()
            .HasKey(c => new { c.CustomerUserID });

        modelBuilder.Entity<CustomerUser>()
            .HasRequired(p => p.Customer)
            .WithMany(c => c.CustomerUsers)
            .HasForeignKey(p => new {p.CompanyID, p.CustomerID});

如何以及在何处声明我的 DbContext？目前我有一个由网络应用程序引用的程序集。另外，这对我的部署有何影响？仅用于引用其键的那个表已经存在，而其余表，我还没有在 SqlServer 中创建(它们存在于我的 VS2012 Server Explorer 中)。

使用此设计我会遇到任何与部署相关的问题吗？

Answer 1

How and where do i declare my DbContexts?

大问题。数据访问层是典型的。不在核心/领域层。这将核心与 EF 耦合。

Currently I have an assembly that is referenced by the web app. Also, how would this pan out for my deployment?

如果您不使用 CORE/DOMAIN 层 + 数据访问层 + UI 层，开发将与数据访问工具紧密耦合。

That one table used for just referencing its key is already existing, while the rest of the tables, I will have yet to create in SqlServer(they're existing in my VS2012 Server Explorer). Would there be any deployment-related issues I could run into with this design?

不，来自一个解决方案的多上下文多数据库访问对于 EF 来说不是问题。尽管实例化上下文的方式需要谨慎管理。例如https://stackoverflow.com/a/20118259/1347784