Asp.Net Foreach和groupby

Question

I want get all my records and group by ProgramId and then view this.

var userProgramsStats = (from a in db.Statistics where a.UserId == login.GetUserObject().UserId select a)
                .GroupBy(a => a.ProgramId);

ViewBag.userProgramsStats = userProgramsStats

And in template:

 @foreach (var item in ViewBag.UserProgramsStats)
 {
     @item.MoneyRate
 } 

Unfortunately I see this error:

An unhandled exception has occurred: 'object' does not contain a definition for 'MoneyRate'

I must get all records where userid, and then groupby programid and sum one column MoneyRate . Then I want use like this:

@item.MoneyRate<br /> // sum MoneyRate
@item.OthercolumnNormal

Answer 1

Your error is due to the wrong type of object of your data item : While processing the foreach, the type of your data is not recognized.

You should specify a Data Model :

public class UserStat {

   public double MoneyRate { get; set; }
   public string ColumnNormal {get; set;} 

   public UserStat() { }
   public UserStat(double moneyRate, string columnNormal)
   {
       MoneyRate = moneyRate;
       ColumnNormal = columnNormal;
   }
}

Then in your template, you should :

@foreach (UserStat item in ViewBag.UserProgramsStats)
{
    @item.MoneyRate
}

You might also do something like this:

@foreach (dynamic item in ViewBag.UserProgramsStats)
{
    @item.MoneyRate
}

Using the dynamic keyword will evaluate if the property exist at run time.

Answer 2

You are getting a type error because the type of userProgramsStats does not contain a property MoneyRate.

You say you want to sum the MoneyRate column, to do this you need to project the grouped result into a new type.

Taking your existing query I've added a select statement onto the end of it that projects into a new anonymous type the programId and the sum of the MoneyRate column for each programId.

var result = (from a in db.Statistics where a.UserId login.GetUserObject().UserId select a)
                .GroupBy(a => a.programid)
                .Select(group => new { MoneyRateSum = group.Sum(i => i.MoneyRate), ProgramId = group.Key });

For more information on projecting and anonymous types read https://msdn.microsoft.com/en-us/library/bb397914.aspx .