lambda表达式的实体框架组不起作用？
我正在研究.net MVC很长一段时间。我想显示一个表格，我将一些列和组的总和发送给视图。我面临的问题=＆gt;（行动）
public ActionResult Index()
{
TempData["UserDetails"] = db.UserDetails.Include(x => x.User).ToList();
var financeofstudents = db.Financeofstudents.Include(f => f.Batche).Include(f => f.User).GroupBy(x => x.UserId).Select(x => new
{
debit = x.Sum(item => item.debit),
credit = x.Sum(item => item.credit),
balance = x.Sum(item => item.balance)
}).ToList();
return View(financeofstudents);
}
呀！可能是它的工作正常，但我不知道。因为我在客户端遇到了一些错误。
当我只是在客户端发送一个列表的工作文件时。似乎=＆gt;
var financeofstudents = db.Financeofstudents.Include(f => f.Batche).Include(f => f.User).ToList();
但是当我使用这个=＆gt;（因为我需要一个小组）==＆gt;
var financeofstudents = db.Financeofstudents.Include(f => f.Batche).Include(f => f.User).GroupBy(x => x.UserId).Select(x => new
{
debit = x.Sum(item => item.debit),
credit = x.Sum(item => item.credit),
balance = x.Sum(item => item.balance)
}).ToList();
我得到的错误就像=＆gt;
和我的观点=＆gt;
@using TSMS_Atp_2_Final_Project.Models.Com.Tsms
@model IEnumerable<Financeofstudent>
@{
ViewBag.Title = "Finance";
IEnumerable<UserDetail> UserDetailsTable = TempData["UserDetails"] as IEnumerable<UserDetail>;
}
<h2>Available Finance Detail Of Students...</h2>
<p>
<a href="@Url.Action("ASIB", "Batche")" class="btn btn-primary btn-sm">Assign New</a>
</p>
<div class="table-responsive">
<table class="table table-striped table-inverse table-bordered">
<tr>
<th>
@Html.DisplayNameFor(model => model.Batche.batch_code)
</th>
<th>
@Html.DisplayNameFor(model => model.Batche.name)
</th>
<th>
@Html.DisplayNameFor(model => model.User.UserId)
</th>
<th>
@Html.Label("Full Name")
</th>
<th>
@Html.DisplayNameFor(model => model.debit)
</th>
<th>
@Html.DisplayNameFor(model => model.credit)
</th>
<th>
@Html.DisplayNameFor(model => model.balance)
</th>
<th>
@Html.DisplayNameFor(model => model.lastTrunsaction)
</th>
<th></th>
</tr>
@foreach (var item in Model)
{
<tr>
<td>
@Html.ActionLink(item.Batche.batch_code, "Details", "Batche", new { id = item.Batche.batch_code }, null)
</td>
<td>
@Html.ActionLink(item.Batche.name, "Details", "Course", new { id = item.Batche.name }, null)
</td>
<td>
@Html.DisplayFor(modelItem => item.User.UserId)
</td>
<td>
@{
var UserDetailsId = UserDetailsTable.Where(x => x.UserId == item.User.UserId).Select(x => x.id).FirstOrDefault();
var FullName = UserDetailsTable.Where(x => x.UserId == item.User.UserId).Select(x => x.fullname).FirstOrDefault();
}
@Html.ActionLink(FullName, "Details", "Students", new { id = UserDetailsId }, null)
</td>
<td>
@Html.DisplayFor(modelItem => item.debit)
</td>
<td>
@Html.DisplayFor(modelItem => item.credit)
</td>
<td>
@Html.DisplayFor(modelItem => item.balance)
</td>
<td>
@Html.DisplayFor(modelItem => item.lastTrunsaction)
</td>
<td>
<div style="width:80px;">
@Html.ActionLink("Edit", "Edit", new { id = item.id }) |
@Html.ActionLink("Details", "Details", new { id = item.id }) |
@Html.ActionLink("Delete", "Delete", new { id = item.id })
</div>
</td>
</tr>
}
</table>
</div>
然后我在网上搜索，发现我需要使用=＆gt;
@model IEnumerable<System.Linq.IGrouping<object,Financeofstudent>>
的实例
@model IEnumerable<Financeofstudent>
这......
我用过，也许问题解决了！但是之后我现在得到的错误就像=＆gt;
我试图找到解决方案并找到
可能是它的解决方案，但我不理解任何事情。
我的模特=＆gt;
public class Financeofstudent
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int id { get; set; }
/// <summary>
/// /////////
/// </summary>
[Required(AllowEmptyStrings = false, ErrorMessage = "User Id Is Required!")]
[MaxLength(12, ErrorMessage = "The Max length Of User ID is 12 character!")]
[RegularExpression("[1-3]{2}-[0-9]{5}-[123]{1}|[1-3]{2}-[0-9]{7}-[123]{1}", ErrorMessage = "Invalid Id,It should [xx]-[xxxxx]-[x] or [xx]-[xxxxxxx]-[x]!")]
[Display(Name = "User ID")]
public string UserId { get; set; }
/// <summary>
/// ////////
/// </summary>
[Required(AllowEmptyStrings = false, ErrorMessage = "Batch Code Is Required!")]
[MaxLength(700, ErrorMessage = "The Max Length For Batch Code Is 700 Character!")]
[Display(Name = "Batch Code")]
public string batch_code { get; set; }
/// <summary>
/// ////////
/// </summary>
[Required(ErrorMessage = "Debit Is Required!")]
[RegularExpression("^[0-9]*$", ErrorMessage = "Invalid Number!")]
[Display(Name = "Debit Amount")]
public int debit { get; set; }
/// <summary>
/// ////////
/// </summary>
[Required(ErrorMessage = "Credit Is Required!")]
[RegularExpression("[0-9]*", ErrorMessage = "Invalid Number!")]
[Display(Name = "Credit Amount")]
public int credit { get; set; }
/// <summary>
/// /////////
/// </summary>
[Required(ErrorMessage = "Balance Is Required!")]
[RegularExpression("[0-9]*", ErrorMessage = "Invalid Number!")]
[Display(Name = "Current Balance")]
public int balance { get; set; }
/// <summary>
/// //////////
/// </summary>
[DataType(DataType.Date, ErrorMessage = "Invalid Date!")]
[Display(Name = "Last Trunsaction Date")]
public DateTime lastTrunsaction { get; set; }
[Display(Name = "Date Of Entry")]
[DataType(DataType.DateTime, ErrorMessage = "Invalid Date!")]
public DateTime entry_date { get; set; }
///relationship with anothere table
[ForeignKey("UserId")]
public User User { get; set; }
/// <summary>
/// ///////
/// </summary>
[ForeignKey("batch_code")]
public Batche Batche { get; set; }
}
我期待像=＆gt;
这样的东西 
和query =＆gt;
select UserId,sum(debit),sum(credit),sum(balance) from Financeofstudents group by UserId;
如上表所示？请帮助我。我可以解决我的问题。或者我做错了什么。或者还有其他方法来获得我的愿望。
3 个答案:
答案 0 :(得分：0)
您的组只返回3个整数的列表。该列表在他们根据您的视图建模时是过时的。您无权访问任何数据库对象属性。
基本上，执行的SQL只获取3个Sums的列表......
答案 1 :(得分：0)
看看这段代码：
.Select(x => new
{
debit = x.Sum(item => item.debit),
credit = x.Sum(item => item.credit),
balance = x.Sum(item => item.balance)
}).ToList();
它返回匿名类型，但您的视图使用了IEnumerable＆lt; Financeofstudent＆GT;模型。
尝试这样做：
创建类FinanceofstudentModel
class FinanceofstudentsModel
{
public string UserId { get; set; }
public int Debit { get; set; }
public int Credit { get; set; }
public int Balance { get; set; }
}
而不是将您的选择更改为此类
var financeofstudents = db.Financeofstudents
.Include(f => f.Batche)
.Include(f => f.User)
.GroupBy(x => x.UserId)
.Select(x => new FinanceofstudentsModel()
{
UserId = x.Key,
Debit = x.Sum(item => item.debit),
Credit = x.Sum(item => item.credit),
Balance = x.Sum(item => item.balance)
});
在您的视图中使用此模型
@model IEnumerable<FinanceofstudentModel>
您的观点可能如下所示：
@model IEnumerable<FinanceofstudentModel>
@foreach (var fm in Model)
{
<p>User: @fm.UserId Debit: @fm.Debit Credit: @fm.Credit Balance: @fm.Balance</p>
<hr/>
}
因此，您的模型只有4个属性（UserId，Debit，Credit和Balance）非常重要。如果要添加额外的属性，则应将其添加到FinanceofstudentModel中并填写控制器。
我希望这可以帮到你
答案 2 :(得分：-1)
创建一个类：
public class StudentFinance
{
public double debit { get; set; }
public double credit { get; set; }
public double balance { get; set; }
}
将LINQ查询更改为
var financeofstudents = db.Financeofstudents.Include(f => f.Batche).Include(f => f.User).GroupBy(x => x.UserId).Select(x => new StudentFinance
{
debit = x.Sum(item => item.debit),
credit = x.Sum(item => item.credit),
balance = x.Sum(item => item.balance)
}).ToList();
现在最后，将视图上的模型更改为：
@model IEnumerable<StudentFinance>
这应该可以正常工作..如果能解决你的问题，请标记答案。
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