Asp.net mvc 在EF MVC中应用左内联接

我有以下SQL语法：

如何将该语法应用于MVC中的EF sytax？我目前在EF中的语法是：

var recordManagementAPs = db.RecordManagementAPs.Include(r => r.MasterAP).Include(r => r.MasterLocation).Include(r => r.MasterRack);
return View(recordManagementAPs.ToList());

有什么想法吗？ 非常感谢。 谢谢。

投影

为视图的数据声明视图模型。而不是传递实体

[Serializable]
public class RecordDetailViewModel
{
    public int MasterAPId { get; set; }
    public string Year { get; set; }
    public string Month { get; set; }
    public string DocumentNumber { get; set; }
    public string BoxNumber { get; set; }
    public string LocationShortName { get; set; }
    public string RackShortName { get; set; }
}

将实体查询投影到视图模型中并返回：

var viewModels = db.MasterAPs
    .Where(x => x.Month == month) // "2"
    .Select(x => new RecordDetailViewModel
    {
        MasterAPId = x.MasterAPId,
        Year = x.Year,
        Month = x.Month,
        DocumentNumber = x.DocumentNumber,
        BoxNumber = x.RecordManagementAP.BoxNumber,
        LocationShortName = x.MasterLocation.LocationShortName,
        RackShortName = x.MasterRack.RackShortName
     }).ToList();

假设您的实体关系已映射

---

当您返回整个实体并希望预取相关实体时，会使用Include关键字。如果访问这些实体，则会包含它们，而不是延迟加载它们。通常，如果要执行更新之类的操作，即接受视图模型或一组字段以从视图更新、加载实体并在保存实体之前应用更新，则仅应检索实体和相关实体。不要将实体传递给视图。这会暴露更多有关域的信息，需要更多内存，并且在序列化关系时可能会导致错误或性能缺陷。从视图接收实体更糟糕，因为它会使您的系统容易受到意外篡改、潜在的附加引用错误以及使用过时更改覆盖数据的攻击。

您可以通过以下方式编写查询：

var query = (from a in Context.MasterAP
            join b in Context.RecordManagementAP on new { a.MasterAPID } equals new { b.MasterAPID }
            into b1
            from b in b1.DefaultIfEmpty()
            join c in Context.MasterLocation on new { b.LocationID } equals new { c.LocationID }
            into c1
            from c in c1.DefaultIfEmpty()
            join d in Context.MasterRack on new { b.RackID } equals new { d.RackID }
            into d1
            from d in d1.DefaultIfEmpty()
            where a.Month == 2
            select new //Write YourModelName Here After new kwyword
            {
                Year = a.Year,
                Month = a.Month,
                DocumentNumber = a.DocumentNumber,
                BoxNumber = b.BoxNumber,
                LocationShortName = c.LocationShortName, 
                RackShortName = d.RackShortName
            });

var query = (from a in Context.MasterAP
            join b in Context.RecordManagementAP on new { a.MasterAPID } equals new { b.MasterAPID }
            into b1
            from b in b1.DefaultIfEmpty()
            join c in Context.MasterLocation on new { b.LocationID } equals new { c.LocationID }
            into c1
            from c in c1.DefaultIfEmpty()
            join d in Context.MasterRack on new { b.RackID } equals new { d.RackID }
            into d1
            from d in d1.DefaultIfEmpty()
            where a.Month == 2
            select new //Write YourModelName Here After new kwyword
            {
                Year = a.Year,
                Month = a.Month,
                DocumentNumber = a.DocumentNumber,
                BoxNumber = b.BoxNumber,
                LocationShortName = c.LocationShortName, 
                RackShortName = d.RackShortName
            });