EF4 和 MVC3 将 ViewModel 映射到实体

Question

我有一个 EF4 实体工作组。以下是该模型的元数据以供参考。

    [MetadataType(typeof(WorkgroupMetaData))]
public partial class Workgroup {
    public Contact manager { get; set; }
}

[Bind(Exclude = "id")]
public class WorkgroupMetaData
{
    [ScaffoldColumn(false)]
    public int id { get; set; }

    [DisplayName("Org. Number")]
    [Required(ErrorMessage = "Org. Number is required.")]
    public string org_number { get; set; }

    [DisplayName("Workgroup Name")]
    [Required(ErrorMessage = "Workgroup name is required.")]
    public string name { get; set; }

    [DisplayName("Customer Contact")]
    public int customer_contact_id { get; set; }

    [DisplayName("Manager")]
    public int manager_id { get; set; }

    [DisplayName("Tech. Lead")]
    public int lead_id { get; set; }

    [DisplayName("Time Approver")]
    public int time_approver { get; set; }

    [DisplayName("Description")]
    public string description { get; set; }

    [ScaffoldColumn(false)]
    public object created_at { get; set; }

    [ScaffoldColumn(false)]
    public object last_modified_at { get; set; }
}

我有一个 ViewModel 定义为：

    public class WorkgroupViewModel
{
    public Workgroup Workgroup { get; set; }
    public List<Workgroup> Workgroups { get; set; }
}

在视图中，我有一个网格来转储可用的工作组。这可行，但我想知道如何将 ID 字段转换为另一个表中的实际字符串。基本上，经理、customer_contact、lead 都是对 Contact 实体的引用。我想显示联系人中的姓名，而不仅仅是 id。

如何做到这一点？我环顾四周，但似乎找不到建议或答案。也许我从错误的角度看待这个问题？

Answer 1

您可以考虑使用 Workgroup（装饰器模式）或 Tuple 的包装器，或者创建一个将它们绑定在一起的自定义类。

public class WorkgroupDisplayModel
{
    public Workgroup Workgroup { get; set; }
    public Manager Manager { get; set; }
    // Add additional properties for each related type
}

在您的 EF 查询中，您可以执行以下操作：

var query = from w in Context.Workgroups
            join m in Context.Managers
                on w.manager_id equals m.uid
            // Additional joins for each related table
            where w.Description == "Project 1" // Whatever criteria
            select Tuple.Create(w, m); // Add param for each type
            //or
            //select new WorkgroupDisplayModel { Workgroup = w, Manager = m, ... };
var list = query.ToList();
var contact = list[0].Item1; // Tuple has strongly typed Item1 thru ItemN
var manager = list[0].Item2;

那么你的视图模型可能有：

List<Tuple<Workgroup, Manager, Customer, Lead>> Workgroups { get; set; }

或

List<WorkgroupDisplayModel> Workgroups { get; set; }