/**
* <summary>
* This method gets the student data from the DB
* </summary>
*
* @method GetStudents
* @returns {void}
*/
protected void GetStudents()
{
// connect to EF
using (DefaultConn db = new DefaultConn()) {
//create query string
string SortString = Session["SortColumn"].ToString() + " " + Session["SortDirection"].ToString();
// query the Students Table using EF and LINQ
var Students = (from allStudents in db.Students
select new { allStudents.StudentID, allStudents.LastName, allStudents.FirstMidName, allStudents.EnrollmentDate });
// bind the result to the GridView
StudentsGridView.DataSource = Students.AsQueryable().OrderBy(SortString).ToList();
StudentsGridView.DataBind();
}
}
/**
* <summary>
* This method gets the student data from the DB
* </summary>
*
* @method GetDepartments
* @returns {void}
*/
protected void GetDepartments()
{
// connect to EF
using (DefaultConn db = new DefaultConn()) {
//create query string
string SortString = Session["SortColumn"].ToString() + " " + Session["SortDirection"].ToString();
// query the Students Table using EF and LINQ
var Departments = (from allDepartments in db.Departments
select allDepartments);
// bind the result to the GridView
DepartmentsGridView.DataSource = Departments.AsQueryable().OrderBy(SortString).ToList();
DepartmentsGridView.DataBind();
}
}
protected void GetDepartment()
{
//populate form with existing student record
int DepartmentID = Convert.ToInt32(Request.QueryString["DepartmentID"]);
//connect to database with ef
using (DefaultConn db = new DefaultConn()) {
//populate student instance with student id with url param
Department updatedDepartment = (from department in db.Departments
where department.DepartmentID == DepartmentID
select department).FirstOrDefault();
if (updatedDepartment != null)
{
NameTextBox.Text = updatedDepartment.Name.ToString();
BudgetTextBox.Text = updatedDepartment.Budget.ToString();
}
}
}
protected void GetStudent()
{
//populate form with existing student record
int StudentID = Convert.ToInt32(Request.QueryString["StudentID"]);
//connect to database with ef
using (DefaultConn db = new DefaultConn()) {
//populate student instance with student id with url param
Student updatedStudent = (from student in db.Students
where student.StudentID == StudentID
select student).FirstOrDefault();
if (updatedStudent != null)
{
LastNameTextBox.Text = updatedStudent.LastName.ToString();
FirstNameTextBox.Text = updatedStudent.FirstMidName.ToString();
EnrollmentDateTextBox.Text = updatedStudent.EnrollmentDate.ToString("yyyy-MM-dd");
}
}
}
protected void SaveButton_Click(object sender, EventArgs e)
{
// Use EF to connect to the server
using (DefaultConn db = new DefaultConn()) {
// use the Student model to create a new student object and
// save a new record
Student newStudent = new Student();
int StudentID = 0;
if (Request.QueryString.Count > 0) // our URL has a StudentID in it
{
// get the id from the URL
StudentID = Convert.ToInt32(Request.QueryString["StudentID"]);
// get the current student from EF DB
newStudent = (from student in db.Students
where student.StudentID == StudentID
select student).FirstOrDefault();
}
// add form data to the new student record
newStudent.LastName = LastNameTextBox.Text;
newStudent.FirstMidName = FirstNameTextBox.Text;
newStudent.EnrollmentDate = Convert.ToDateTime(EnrollmentDateTextBox.Text);
// use LINQ to ADO.NET to add / insert new student into the database
if (StudentID == 0)
{
db.Students.Add(newStudent);
}
// save our changes - also updates and inserts
db.SaveChanges();
// Redirect back to the updated students page
Response.Redirect("~/Students.aspx");
}
}
/**
* <summary>
* This method is used to detelte student records from the database using ef
* </summary>
*
* @method StudentsGridView_RowDeleting
* @param {object} sender
* @param {GridViewDeleteEventArgs} e
* @return {void}
*/
protected void StudentsGridView_RowDeleting(object sender, GridViewDeleteEventArgs e)
{
// store which row was selected for deletion
int selectedRow = e.RowIndex;
// get the selected StudentID using the grid's Datakey collection
int StudentID = Convert.ToInt32(StudentsGridView.DataKeys[selectedRow].Values["StudentID"]);
// use EF to find the selected student from DB and Remove it
using (DefaultConn db = new DefaultConn()) {
Student deletedStudent = (from studentRecords in db.Students
where studentRecords.StudentID == StudentID
select studentRecords).FirstOrDefault();
// remove the student record from the database
db.Students.Remove(deletedStudent);
// save changes to the db
db.SaveChanges();
// refresh the grid
this.GetStudents();
}
}
