c# - ASP.NET MVC 和实体 - 使用原始 SQL 时加载导航属性/对象

Question

我正在开发一个应用程序，该应用程序根据用户在表单中选择的选项生成“报告” View 。由于我根据用户输入“动态”生成必要的数据库查询，因此我选择使用原始 SQL，而不是 LINQ 查询。

  [HttpPost]
   public  ActionResult GeneratedReport(String StartDate, String EndDate, String EquipmentID, String LocationID, String UserID )
    {
        String sqlQuery = String.Format("SELECT * from Records WHERE RecordDate BETWEEN '{0}' and '{1}'", StartDate, EndDate);
        GeneratedReportViewModel vm = new GeneratedReportViewModel();
        List<Record> records;

        bool userFilter = (UserID == "") ? false : true;
        bool locationFilter = (LocationID == "") ? false : true;
        bool equipmentFilter = (EquipmentID == "") ? false : true;

        if(userFilter) {
            sqlQuery += " AND UserID = " + UserID;
        } if(locationFilter) {
            sqlQuery += " AND LocationID = " + LocationID;
        } if(equipmentFilter) {
            sqlQuery += " AND EquipmentID = " + EquipmentID;
        }

        records = dbContext.Database.SqlQuery<Record>(sqlQuery).ToList();
       vm.FilteredRecords = records;

       return View("GeneratedReport", vm);

    }
}

实体生成的Record类的定义:

{
    using System;
    using System.Collections.Generic;
    using System.ComponentModel.DataAnnotations;
    using System.ComponentModel.DataAnnotations.Schema;
    using System.Data.Entity.Spatial;

    public partial class Record
    {
        public int RecordID { get; set; }

        public DateTime RecordDate { get; set; }

        public int EquipmentID { get; set; }

        public int ActionTypeID { get; set; }

        public int UserID { get; set; }

        [StringLength(200)]
        public string Notes { get; set; }

        public int LocationID { get; set; }

        public virtual Action Action { get; set; }

        public virtual Equipment Equipment { get; set; }

        public virtual Location Location { get; set; }

        public virtual User User { get; set; }
    }
}

但是，每当服务器尝试加载与GenerateReport 关联的 View (代码如下)时，Record 对象的所有导航属性(用户、位置、设备、操作)都为空。

@model IT_Equipment_Log.ViewModels.GeneratedReportViewModel

@{
    ViewBag.Title = "GeneratedReport";
}

<table>
    <tr><th>Equipment</th><th>User</th><th>Date</th><th>Location</th><th>Action</th><th>Notes</th></tr>

    @foreach (var record in @Model.FilteredRecords)
    {
        <tr><td>@record.Equipment.SerialNumber</td><td>@record.User.FullName</td><td>@record.RecordDate</td><td>@record.Location.DisplayName</td><td>@record.Action.Description</td><td>@record.Notes</td></tr>
    }

</table>

我不知道如何使 Include() 在这种情况下工作，也不知道如何将此 SQL 语句(因为它会根据用户输入而变化)转换为 LINQ 查询。是否还有其他可用选项，或者我如何解决此问题？

非常感谢。

Answer 1

我尝试使用 LINQ 重写您的代码。猜测它会获得您想要的导航属性。

var records = dbContext.Record.Where(p => p.RecordDate >= StartDate && p.RecordDate <= EndDate);
if(!string.IsNullOrEmpty(UserID)){
    records.Where(p => p.UserID = UserID);
}

if(!string.IsNullOrEmpty(LocationID)){
    records.Where(p => p.LocationID = LocationID);
}

if(!string.IsNullOrEmpty(EquipmentID)){
    records.Where(p => p.EquipmentID = EquipmentID);
}

var vm = vm = new GeneratedReportViewModel{
    FilteredRecords = records
};

return View("GeneratedReport", vm);