I defined the name space of this class, you can see below,But it is very strange to say that the namespace was not defined in Method OnPostCreateOrEdit. There is a name space(using EducationManagement.Application.Contract.CourseLevel)

namespace EducationManagement.Application.Contract.CourseLevel {

    public class EditCoursLevel
    {
        public long Id { get; set; }
        public string  Title { get; set; }             
    }

}

  public JsonResult OnPostCreateOrEdit(long id, EditCourseLevel CourseLevel)
{
    if (ModelState.IsValid)
    {
        if (id == 0)
        {
             _CourseLevelApplication.CreateLevel(CourseLevel);
             _unitOfWork.Commit();
        }
        else
        {
             _CourseLevelApplication.EditCourseLevel(CourseLevel);
             _unitOfWork.Commit();
        }
        lstLevel =  _CourseLevelApplication.GetCourseLevelForDisplay();
        var html =  _renderService.ToString("_ViewAll", lstLevel);
        return new JsonResult(new { isValid = true, html = html });
    }
    else
    {
        var html =  _renderService.ToString("_CreateOrEdit", CourseLevel);
        return new JsonResult(new { isValid = false, html = html });
    }
}

CodePudding user response：

public class EditCoursLevel   <-- TYPO! Change to EditCourseLevel 
{
    public long Id { get; set; }
    public string  Title { get; set; }             
}