如何将查询中的项目添加到List< StudentDetails> ？ [英] How can I add items in a query to the List<StudentDetails> ?

问题描述

我已经提到以下链接：



http://www.aspdotnet-suresh.com/2012/03/bind-data-to-gridview-with-jquery-or.html [< a href =http://www.aspdotnet-suresh.com/2012/03/bind-data-to-gridview-with-jquery-or.html\"target =_ blanktitle =New Window> ^ ]



我在.asmx文件中编写了以下代码，并在.aspx文件中调用此WebMethod

 使用 JSON：
 
 [WebMethod] 
  public  StudentDetails [] GetTodayReport（ int  StudentID，DateTime startdate）
 {
  try  
 {
 context =  new  TMSEntities（）; 
列表< studentdetails> details =  new 列表< studentdetails>（）; 
 List< string> sdetails =  new  List< string>（）; 
 DataTable NewTable =  new  DataTable（）; 
 NewTable.Columns.AddRange（ new  DataColumn [ 6 ] { new  DataColumn（ 输入， typeof （ string ））， new  DataColumn（  StartDate， typeof （ string ））， new  DataColumn（ 名称， typeof （ string ））， new  DataColumn（ 状态， typeof （ string ））， n ew  DataColumn（  EndDate， typeof （ string ））， new  DataColumn（  课程， typeof （ string ））}）; 
  var  query =（ from  E  in  context.tbl_ExamCreation 
  join  EA   context.tbl_ExamAttendence on E.Exam_ID等于EA .Exam_ID 
  join  C   context.tbl_Course on E.Course_ID等于C.CourseID 
 其中 EA.StudentID == StudentID&& SqlFunctions.DateDiff（  DAY，E.DateOfExam，startdate）==  0 && E.Status ==   
 选择  new  {Typ e =  考试，StartDate = E.DateOfExam，Name = E.ExamName，Status = EA。 status，EndDate = E.ExamEndDatetime，Course = C.Name}）
 .Union 
（ from  LS  in  context.tbl_LectureScheduling 
  join  LA  in  context.tbl_LectureAttendence on LS .LectureScheduleID等于LA.LectureScheduleID 
  join  L 在 context.tbl_Lectures on LS.LectureID等于L .LectureID 
  join  CR   context.tbl_Course on L.CourseID等于CR.CourseID 
 其中 LA.StudentID == StudentID&& SqlFunctions.DateDiff（  DAY，LS.StartDateTime，startdate）==  0 && LS.Status ==   A 
 选择  new  {Type =   Lecture ，StartDate = LS.StartDateTime，Name = L.LectureName，Status = LA.status，EndDate = LS.EndDateTime，Course = CR.Name} 
）; 
  foreach （ var  item  in 查询）
 {
  //  这里我想将上面的查询结果添加到详细信息中list< studentdetails>类型的列表 
} 
 
} 
  catch （例外情况）
 {
  return   null ; 
} 
} 
} 
  public   class  StudentDetails 
 {
  public   string 输入{获得;  set ;} 
  public   string  StartDate { get ;  set ; } 
  public   string 名称{ get ;  set ; } 
  public   string 状态{ get ;  set ; } 
  public   string  EndDate { get ;  set ; } 
  public   string 课程{ get ;  set ; } 
} 
 
} 

我想将上面的查询结果添加到详细信息列表中，该列表的类型为List< studentdetails>在上面循环。那我怎么能这样做？

解决方案

用这个替换你的查询部分

列表与LT; studentdetails> query =（ from  E  in  context.tbl_ExamCreation 
 加入 EA   context.tbl_ExamAttendence on E.Exam_ID等于EA.Exam_ID 
  join  C   context.tbl_Course on E.Course_ID等于C.CourseID 
 其中 EA。 StudentID == StudentID&& SqlFunctions.DateDiff（  DAY，E.DateOfExam，startdate） ==  0 && E.Status ==   
 选择  new  {Type =  考试，StartDate = E.DateOfExam，Name = E.ExamName，Status = EA.status，EndDate = E.ExamEndDatetime，Course = C.Name}）
 .Union 
（来自 LS  in  context.tbl_LectureScheduling 
 加入 LA 在 context.tbl_LectureAttendence on LS.LectureScheduleID等于LA.LectureScheduleID 
  join  L   context.tbl_Lectures on LS.LectureID equals L.LectureID 
  join  CR  context.tbl_Course上的class =code-keyword> L.CourseID等于CR.CourseID 
 其中 LA.StudentID == StudentID& ;&安培; SqlFunctions.DateDiff（  DAY，LS.StartDateTime，startdate）==  0 && LS.Status ==   A 
 选择  new  StudentDetails（）{Type =  讲座，StartDate = LS.StartDateTime，Name = L.LectureName，Status = LA.status，EndDate = LS.EndDateTime，Course = CR.Name} 
）.ToList（）; 

而不是foreach使用

  return  query.Select（x => new StudentDetails（）{Type = x.Type，StartDate = x.StartDate.HasValue？x.StartDate.Value：DateTime.MinValue，...} ）.ToArray（）; 

I have referred following link :

http://www.aspdotnet-suresh.com/2012/03/bind-data-to-gridview-with-jquery-or.html[^]

I have written following code in .asmx file and calling this WebMethod in .aspx file

using JSON:

 [WebMethod]
        public StudentDetails[] GetTodayReport(int StudentID, DateTime startdate)
        {
            try
            {
                context = new TMSEntities();
                List<studentdetails> details = new List<studentdetails>();
                List<string> sdetails = new List<string>();
                DataTable NewTable = new DataTable();
                NewTable.Columns.AddRange(new DataColumn[6] { new DataColumn("Type", typeof(string)), new DataColumn("StartDate", typeof(string)), new DataColumn("Name", typeof(string)), new DataColumn("Status", typeof(string)), new DataColumn("EndDate", typeof(string)), new DataColumn("Course", typeof(string)) });
                var query = (from E in context.tbl_ExamCreation
                             join EA in context.tbl_ExamAttendence on E.Exam_ID equals EA.Exam_ID
                             join C in context.tbl_Course on E.Course_ID equals C.CourseID
                             where EA.StudentID == StudentID && SqlFunctions.DateDiff("DAY", E.DateOfExam, startdate) == 0 && E.Status == "A"
                             select new { Type = "Exam", StartDate = E.DateOfExam, Name = E.ExamName, Status = EA.status, EndDate = E.ExamEndDatetime, Course = C.Name })
                           .Union
                           (from LS in context.tbl_LectureScheduling
                            join LA in context.tbl_LectureAttendence on LS.LectureScheduleID equals LA.LectureScheduleID
                            join L in context.tbl_Lectures on LS.LectureID equals L.LectureID
                            join CR in context.tbl_Course on L.CourseID equals CR.CourseID
                            where LA.StudentID == StudentID && SqlFunctions.DateDiff("DAY", LS.StartDateTime, startdate) == 0 && LS.Status == "A"
                            select new { Type = "Lecture", StartDate = LS.StartDateTime, Name = L.LectureName, Status = LA.status, EndDate = LS.EndDateTime, Course = CR.Name }
                            );
                foreach(var item in query)
                {
                   // Here I want to add above query result into "details" list which is of type   List<studentdetails> 
                }
              
            }
            catch (Exception ex)
            {
                return null;
            }
        }
    }
    public class StudentDetails
    {
        public string Type{get; set;}
        public string StartDate { get; set; }
        public string Name { get; set; }
        public string Status { get; set; }
        public string EndDate { get; set; }
        public string Course { get; set; }
    }

}

I want to add above query result into "details" list which is of type List<studentdetails> in above for loop. So how can I do the same?

解决方案

Replace your query porion with this

List<studentdetails> query = (from E in context.tbl_ExamCreation
                             join EA in context.tbl_ExamAttendence on E.Exam_ID equals EA.Exam_ID
                             join C in context.tbl_Course on E.Course_ID equals C.CourseID
                             where EA.StudentID == StudentID && SqlFunctions.DateDiff("DAY", E.DateOfExam, startdate) == 0 && E.Status == "A"
                             select new { Type = "Exam", StartDate = E.DateOfExam, Name = E.ExamName, Status = EA.status, EndDate = E.ExamEndDatetime, Course = C.Name })
                           .Union
                           (from LS in context.tbl_LectureScheduling
                            join LA in context.tbl_LectureAttendence on LS.LectureScheduleID equals LA.LectureScheduleID
                            join L in context.tbl_Lectures on LS.LectureID equals L.LectureID
                            join CR in context.tbl_Course on L.CourseID equals CR.CourseID
                            where LA.StudentID == StudentID && SqlFunctions.DateDiff("DAY", LS.StartDateTime, startdate) == 0 && LS.Status == "A"
                            select new StudentDetails(){ Type = "Lecture", StartDate = LS.StartDateTime, Name = L.LectureName, Status = LA.status, EndDate = LS.EndDateTime, Course = CR.Name }
                            ).ToList();

instead of foreach use

return query.Select(x=>new StudentDetails() { Type = x.Type, StartDate = x.StartDate.HasValue ? x.StartDate.Value : DateTime.MinValue,...}).ToArray();

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