protected void GetStudent()
{
//populate form with existing student record
Int32 StudentID = Convert.ToInt32(Request.QueryString["StudentID"]);
//connect to db via EF
using (comp2007Entities db = new comp2007Entities())
{
//populate a student instance with the StudentID from the URL parameter
Student s = (from objS in db.Students
where objS.StudentID == StudentID
select objS).FirstOrDefault();
//map the student properties to the form controls if we found a match
if (s != null)
{
txtLastName.Text = s.LastName;
txtFirstMidName.Text = s.FirstMidName;
txtEnrollmentDate.Text = s.EnrollmentDate.ToString("yyyy-MM-dd");
}
//enrollments - this code goes in the same method that populates the student form but below the existing code that's already in GetStudent()
var objE = (from en in db.Enrollments
join c in db.Courses on en.CourseID equals c.CourseID
join d in db.Departments on c.DepartmentID equals d.DepartmentID
where en.StudentID == StudentID
select new { en.EnrollmentID, en.Grade, c.Title, d.Name});
grdCourses.DataSource = objE.ToList();
grdCourses.DataBind();
}
}
protected void GetCourses()
{
using (comp2007Entities db = new comp2007Entities())
{
String SortString = Session["SortColumn"].ToString() + " " + Session["SortDirection"].ToString();
var Courses = from c in db.Courses
select new { c.CourseID, c.Title, c.Credits, c.Department.Name } ;
grdCourses.DataSource = Courses.AsQueryable().OrderBy(SortString).ToList();
grdCourses.DataBind();
}
}
protected void GetStudents()
{
//connect to EF
using (comp2007Entities db = new comp2007Entities())
{
//query the students table using EF and LINQ
var Students = from s in db.Students
select s;
//bind the result to the gridview
grdStudents.DataSource = Students.ToList();
grdStudents.DataBind();
}
}
protected void grdCourses_RowDeleting(object sender, GridViewDeleteEventArgs e)
{
//get selected course ID
Int32 CourseID = Convert.ToInt32(grdCourses.DataKeys[e.RowIndex].Values["CourseID"]);
using (comp2007Entities db = new comp2007Entities())
{
//get selected course
Course objC = (from c in db.Courses
where c.CourseID == CourseID
select c).FirstOrDefault();
//delete
db.Courses.Remove(objC);
db.SaveChanges();
//refresh grid
GetCourses();
}
}
protected void btnSave_Click(object sender, EventArgs e)
{
//use EF to connect to SQL Server
using (comp2007Entities db = new comp2007Entities())
{
//use the Student model to save the new record
Student s = new Student();
Int32 StudentID = 0;
//check the querystring for an id so we can determine add / update
if (Request.QueryString["StudentID"] != null)
{
//get the id from the url
StudentID = Convert.ToInt32(Request.QueryString["StudentID"]);
//get the current student from EF
s = (from objS in db.Students
where objS.StudentID == StudentID
select objS).FirstOrDefault();
}
s.LastName = txtLastName.Text;
s.FirstMidName = txtFirstMidName.Text;
s.EnrollmentDate = Convert.ToDateTime(txtEnrollmentDate.Text);
//call add only if we have no student ID
if (StudentID == 0)
{
db.Students.Add(s);
}
//run the update or insert
db.SaveChanges();
//redirect to the updated students page
Response.Redirect("students.aspx");
}
}
protected void grdStudents_RowDeleting(object sender, GridViewDeleteEventArgs e)
{
//store which row was clicked
Int32 selectedRow = e.RowIndex;
//get the selected StudentID using the grid's Data Key collection
Int32 StudentID = Convert.ToInt32(grdStudents.DataKeys[selectedRow].Values["StudentID"]);
//use EF to remove the selected student from the db
using (comp2007Entities db = new comp2007Entities())
{
Student s = (from objS in db.Students
where objS.StudentID == StudentID
select objS).FirstOrDefault();
//do the delete
db.Students.Remove(s);
db.SaveChanges();
}
//refresh the grid
GetStudents();
}
protected void grdCourses_RowDeleting(object sender, GridViewDeleteEventArgs e)
{
//get selected record id
Int32 EnrollmentID = Convert.ToInt32(grdCourses.DataKeys[e.RowIndex].Values["EnrollmentID"]);
using (comp2007Entities db = new comp2007Entities())
{
//get selected record
Enrollment objE = (from en in db.Enrollments
where en.EnrollmentID == EnrollmentID
select en).FirstOrDefault();
//delete
db.Enrollments.Remove(objE);
db.SaveChanges();
//refresh the data on the page
GetStudent();
}
}
