ASP MVC Nested Models - asp.net-mvc

Question

I need a view that displays rows of header-detail info. For a trivial case I set up a Course-Student tiny database with 4 simple tables. The Courses and Students tables are linked with a Section table which also has a student grade in it. Also, the Student table is owned by a Student Type Table. There are helper classes to hold the list of "header" data for the course and a "detail" list for each student who takes that class.
namespace SchoolA.Models
{
public class CourseInfo2
{
public int CourseID { get; set; }
public int CourseNumber { get; set; }
public string CourseName { get; set; }
public IEnumerable<CourseSectionList> CourseStudentList { get; set; }
}
}
namespace SchoolA.Models
{
public class CourseSectionList
{
public string Student { get; set; }
public string Type { get; set; }
public string Grade { get; set; }
}
}
The controller is:
public ActionResult Courselisting()
{
List<CourseInfo2> courseInfo2 = new List<CourseInfo2>();
List<CourseSectionList> courseSectionList = new List<CourseSectionList>();
var Cquery = from c in db.Courses select c;
foreach (var item in Cquery)
{
Course course = db.Courses.Find(item.CourseID); // first find the selected course
// get the sections
foreach (var s in query) // go through each section
{
// get the section data
courseSectionList.Add(new CourseSectionList
{
Student = student.StudentName,
Type = studentType.StudentTypeName,
Grade = s.SectionStudentGrade
});
} // end of section loop
courseInfo2.Add(new CourseInfo2
{
CourseID = course.CourseID,
CourseNumber = course.CourseNumber,
CourseName = course.CourseName,
CourseStudentList = courseSectionList
});
} // end of Course loop
return View(courseInfo2); // Course List and Section list for each course
}
The View is:
#model SchoolA.Models.CourseInfo2
#* doesn't work either: model List<SchoolA.Models.CourseInfo2>*#
<div>
<table>
<tr><th>ID</th> <th>Number</th> <th>Course</th></tr>
#foreach (var CourseInfo2 in Model)
{
<tr>
<td>
#CourseInfo2.CourseID
</td>
<td>
#CourseInfo2.CourseNumber
</td>
<td>
#CourseInfo2.CourseName
</td>
<td>
<table class="table">
<tr><th>Student</th> <th>Type</th><th>Grade</th></tr>
#foreach (var s in Model.CourseStudentList)
{
<tr>
<td>
#s.Student
</td>
<td>
#s.Type
</td>
<td>
#s.Grade
</td>
</tr>
}
</table>
</td>
</tr>
}
</table>
</div>
The problem is that I get a variety of errors as I try to pass these two models to the view. In the code as shown above I get this error:
CS1579: foreach statement cannot operate on variables of type 'SchoolA.Models.CourseInfo2' because 'SchoolA.Models.CourseInfo2' does not contain a public definition for 'GetEnumerator'
I've tried a number of variations for passing the models but always run into one error other the other that prevents both models from working in the view. I should note that I tested each part of the view independently and the controller code works fine to deliver the correct data to the view. However, I can't combine the two.
The problem seems to be the way I create instances of the models an how they are passed to the view. What am I doing wrong?

Answer 1

You're passing your view a List<SchoolA.Models.CourseInfo2>, but the view expects a single SchoolA.Models.CourseInfo2.
Change your #model declaration to IEnumerable<SchoolA.Models.CourseInfo2>.
Then change your foreach loops.
Change the first loop to foreach (var courseInfo in Model)
Change the inner loop to foreach (var s in courseInfo.CourseStudentList)

Answer 2

You are passing a model which is list of object, while in view you have single object.
Change your view model bind as below:
#model List<SchoolA.Models.CourseInfo2>

Answer 3

Problem: I have to edit Level2Name (by UI it's a textbox inside the child grid).
I'm able to edit Level1name (parent grid text field) and able to get value in my controller.
Question: How do I able to edit the nested textbox.
What I've tried.
Code:
Model
public class Level0
{
public Level0()
{
Level1= new List<Level1>();
}
public int? ID{ get; set; }
public int? NameText{ get; set; }
public List<Level1> lev1{ get; set; }
}
public class Level1
{
public Level1()
{
Level2= new List<Level2>();
}
public int Lev1ID {get;set;}
public string Level1name{ get; set; }
public List<Level2> level2{ get; set; }
}
public class Level2
{
public string Level2_ID { get; set; }
public string Level2Name{ get; set; }
}
UI Code
#for (int i = 0; i < Model.Level1.Count; i++)
{
#Html.HiddenFor(modelItem => Model.Floors[i].Lev1ID )
#for (int j = 0; j < Model.Level1[i].Level2.Count; j++)
{
#Html.HiddenFor(m => m.Level1[i].Level2[j].OP)
#Html.TextBoxFor(m => m.Level1[i].Level2[j].Level2Name, new { #class = "form-control" })
}
}