protected void GetStudents()
{
try
{
//connect to EF
using (DefaultConnectionEF db = new DefaultConnectionEF())
{
//query the students table using EF and LINQ
var Students = from s in db.Students
select s;
//append the current direction to the Sort Column
String Sort = Session["SortColumn"].ToString() + " " + Session["SortDirection"].ToString();
//bind the result to the gridview
grdStudents.DataSource = Students.AsQueryable().OrderBy(Sort).ToList();
grdStudents.DataBind();
}
}
catch (Exception)
{
Response.Redirect("/error.aspx");
}
}
protected void btnAdd_Click(object sender, EventArgs e)
{
try
{
using (DefaultConnectionEF db = new DefaultConnectionEF())
{
//get the values needed
Int32 CourseID = Convert.ToInt32(Request.QueryString["CourseID"]);
Int32 StudentID = Convert.ToInt32(ddlStudent.SelectedValue);
//populate the new enrollment object
Enrollment objE = new Enrollment();
objE.StudentID = StudentID;
objE.CourseID = CourseID;
//save
db.Enrollments.Add(objE);
db.SaveChanges();
//refresh
GetCourse();
}
}
catch (Exception)
{
Response.Redirect("/error.aspx");
}
}
protected void GetCourses()
{
try
{
using (DefaultConnectionEF db = new DefaultConnectionEF())
{
var courses = (from c in db.Courses
select new { c.CourseID, c.Title, c.Credits, c.Department.Name });
//append the current direction to the Sort Column
String Sort = Session["SortColumn"].ToString() + " " + Session["SortDirection"].ToString();
grdCourses.DataSource = courses.AsQueryable().OrderBy(Sort).ToList();
grdCourses.DataBind();
}
}
catch(Exception)
{
Response.Redirect("/error.aspx");
}
}
protected void grdCourses_RowDeleting(object sender, GridViewDeleteEventArgs e)
{
Int32 CourseID = Convert.ToInt32(grdCourses.DataKeys[e.RowIndex].Values["CourseID"].ToString());
try{
using (DefaultConnectionEF db = new DefaultConnectionEF())
{
Course objC = (from c in db.Courses
where c.CourseID == CourseID
select c).FirstOrDefault();
db.Courses.Remove(objC);
db.SaveChanges();
}
}
catch(Exception)
{
Response.Redirect("/error.aspx");
}
GetCourses();
}
protected void btnSave_Click(object sender, EventArgs e)
{
try
{
//connect
using (DefaultConnectionEF conn = new DefaultConnectionEF())
{
//instantiate a new deparment object in memory
Department d = new Department();
//decide if updating or adding, then save
if (Request.QueryString.Count > 0)
{
Int32 DepartmentID = Convert.ToInt32(Request.QueryString["DepartmentID"]);
d = (from dep in conn.Departments
where dep.DepartmentID == DepartmentID
select dep).FirstOrDefault();
}
//fill the properties of our object from the form inputs
d.Name = txtName.Text;
d.Budget = Convert.ToDecimal(txtBudget.Text);
if (Request.QueryString.Count == 0)
{
conn.Departments.Add(d);
}
conn.SaveChanges();
//redirect to updated departments page
Response.Redirect("departments.aspx");
}
}
catch (Exception)
{
Response.Redirect("/error.aspx");
}
}
protected void btnSave_Click(object sender, EventArgs e)
{
try
{
//do insert or update
using (DefaultConnectionEF db = new DefaultConnectionEF())
{
Course objC = new Course();
if (!String.IsNullOrEmpty(Request.QueryString["CourseID"]))
{
Int32 CourseID = Convert.ToInt32(Request.QueryString["CourseID"]);
objC = (from c in db.Courses
where c.CourseID == CourseID
select c).FirstOrDefault();
}
//populate the course from the input form
objC.Title = txtTitle.Text;
objC.Credits = Convert.ToInt32(txtCredits.Text);
objC.DepartmentID = Convert.ToInt32(ddlDepartment.SelectedValue);
if (String.IsNullOrEmpty(Request.QueryString["CourseID"]))
{
//add
db.Courses.Add(objC);
}
//save and redirect
db.SaveChanges();
Response.Redirect("courses.aspx");
}
}
catch (Exception)
{
Response.Redirect("/error.aspx");
}
}
protected void GetDepartments()
{
try
{
//connect using our connection string from web.config and EF context class
using (DefaultConnectionEF conn = new DefaultConnectionEF())
{
//use link to query the Departments model
var deps = from d in conn.Departments
select d;
String Sort = Session["SortColumn"].ToString() + " " + Session["SortDirection"].ToString();
//bind the query result to the gridview
grdDepartments.DataSource = deps.AsQueryable().OrderBy(Sort).ToList();
grdDepartments.DataBind();
}
}
catch (Exception)
{
Response.Redirect("/error.aspx");
}
}
protected void GetDepartment()
{
try
{
//connect
using (DefaultConnectionEF conn = new DefaultConnectionEF())
{
//get id from url parameter and store in a variable
Int32 DepartmentID = Convert.ToInt32(Request.QueryString["DepartmentID"]);
var d = (from dep in conn.Departments
where dep.DepartmentID == DepartmentID
select dep).FirstOrDefault();
//populate the form from our department object
txtName.Text = d.Name;
txtBudget.Text = d.Budget.ToString();
var objE = (from en in conn.Courses
join c in conn.Departments on
en.DepartmentID equals c.DepartmentID
where en.DepartmentID == DepartmentID
select new { en.Title, en.DepartmentID });
grdCourses.DataSource = objE.ToList();
grdCourses.DataBind();
//show the courses
grdCourses.Visible = true;
}
}
catch (Exception)
{
Response.Redirect("/error.aspx");
}
}
protected void grdStudents_RowDeleting(object sender, GridViewDeleteEventArgs e)
{
try
{
//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 (DefaultConnectionEF db = new DefaultConnectionEF())
{
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();
}
catch (Exception)
{
Response.Redirect("/error.aspx");
}
}
protected void GetCourse()
{
//populate the existing course for editing
try
{
using (DefaultConnectionEF db = new DefaultConnectionEF())
{
Int32 CourseID = Convert.ToInt32(Request.QueryString["CourseID"]);
Course objC = (from c in db.Courses
where c.CourseID == CourseID
select c).FirstOrDefault();
//populate the form
txtTitle.Text = objC.Title;
txtCredits.Text = objC.Credits.ToString();
ddlDepartment.SelectedValue = objC.DepartmentID.ToString();
var objE = (from en in db.Enrollments
join d in db.Students on en.StudentID equals d.StudentID
join e in db.Courses on en.CourseID equals e.CourseID
where en.CourseID == CourseID
select new { en.EnrollmentID, d.LastName, d.FirstMidName });
grdStudents.DataSource = objE.ToList();
grdStudents.DataBind();
ddlStudent.ClearSelection();
var studs = from d in db.Students select d;
ddlStudent.DataSource = studs.ToList();
ddlStudent.DataBind();
ListItem newItem = new ListItem("-Select-", "0");
ddlStudent.Items.Insert(0, newItem);
}
}
catch (Exception)
{
Response.Redirect("/error.aspx");
}
}
protected void grdStudents_RowDeleting(object sender, GridViewDeleteEventArgs e)
{
//get the selected EnrollmentID
Int32 EnrollmentID = Convert.ToInt32(grdStudents.DataKeys[e.RowIndex].Values["EnrollmentID"]);
try
{
using (DefaultConnectionEF db = new DefaultConnectionEF())
{
Enrollment objE = (from en in db.Enrollments
where en.EnrollmentID == EnrollmentID
select en).FirstOrDefault();
db.Enrollments.Remove(objE);
db.SaveChanges();
//repopulate the page
GetCourse();
}
}
catch (Exception)
{
Response.Redirect("/error.aspx");
}
}
protected void GetDepartments()
{
try
{
using (DefaultConnectionEF db = new DefaultConnectionEF())
{
var deps = (from d in db.Departments
orderby d.Name
select d);
ddlDepartment.DataSource = deps.ToList();
ddlDepartment.DataBind();
}
}
catch (Exception)
{
Response.Redirect("/error.aspx");
}
}
protected void grdDepartments_RowDeleting(object sender, GridViewDeleteEventArgs e)
{
try
{
//connect
using (DefaultConnectionEF conn = new DefaultConnectionEF())
{
//get the selected DepartmentID
Int32 DepartmentID = Convert.ToInt32(grdDepartments.DataKeys[e.RowIndex].Values["DepartmentID"]);
var d = (from dep in conn.Departments
where dep.DepartmentID == DepartmentID
select dep).FirstOrDefault();
//process the delete
conn.Departments.Remove(d);
conn.SaveChanges();
//update the grid
GetDepartments();
}
}
catch (Exception)
{
Response.Redirect("/error.aspx");
}
}
