/**
* <summary>
* This method gets the student data from the DB
* </summary>
*
* @method GetStudents
* @returns {void}
*/
protected void GetStudents()
{
// Connect to EF
using (ContosoConnection db = new ContosoConnection())
{
string SortString = Session["SortColumn"].ToString() + " " + Session["SortDirection"].ToString();
// Query the Students Table using EF and LINQ
var Students = (from allStudents in db.Students
select allStudents);
// Bind the result to the GridView
StudentsGridView.DataSource = Students.AsQueryable().OrderBy(SortString).ToList();
StudentsGridView.DataBind();
}
}
protected void GetStudent()
{
// Populate the form with existing data from the database
int StudentID = Convert.ToInt32(Request.QueryString["StudentID"]);
// Connect to the EF DB
using (ContosoConnection db = new ContosoConnection())
{
// Populate a student object instance with the StudentId from the URL parameter
Student updatedStudent = (from student in db.Students
where student.StudentID == StudentID
select student).FirstOrDefault();
// Map the student properties to the form controls
if (updatedStudent != null)
{
LastNameTextBox.Text = updatedStudent.LastName;
FirstNameTextBox.Text = updatedStudent.FirstMidName;
EnrollmentDateTextBox.Text = updatedStudent.EnrollmentDate.ToString("yyyy-MM-dd");
}
}
}
protected void SaveButton_Click(object sender, EventArgs e)
{
// Use EF to connect to the server
using (ContosoConnection db = new ContosoConnection())
{
// 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 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 or insert new student into the database
if (StudentID == 0)
{
db.Students.Add(newStudent);
}
// Save our changes
db.SaveChanges();
// Redirect back to the updated students page
Response.Redirect("~/Students.aspx");
}
}
/**
* <summary>
* This event handler deletes a student from the db using EF
* </summary>
*
* @method StudentsGridView_RowDeleting
* @param {object} sender
* @param {GridViewDeleteEventArgs} e
* @returns {void}
*/
protected void StudentsGridView_RowDeleting(object sender, GridViewDeleteEventArgs e)
{
// Store which row was clicked
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 in the DB and remove it
using (ContosoConnection db = new ContosoConnection())
{
// Create object of the Student class and store the query string inside of it
Student deletedStudent = (from studentRecords in db.Students
where studentRecords.StudentID == StudentID
select studentRecords).FirstOrDefault();
// Remove the selected student from the db
db.Students.Remove(deletedStudent);
// Save my changes back to the database
db.SaveChanges();
//refresh the Grid
this.GetStudents();
}
}
/**
* <summary>
* This event handler deletes a department from the databse using EF
* </summary>
* @method DepartmentsGridView_RowDeleting
* @param {object} sender
* @param {GridViewDeleteEventArgs}
* @returns {void}
* */
protected void DepartmentsGridView_RowDeleting(object sender, GridViewDeleteEventArgs e)
{
// Store which row was clicked
int selectedRow = e.RowIndex;
// Get the selected DepartmentID using the grids datakey collection
int DepartmentID = Convert.ToInt32(DepartmentsGridView.DataKeys[selectedRow].Values["DepartmentID"]);
// Use ef to find the selelcted Department and delete it
using (ContosoConnection db = new ContosoConnection())
{
// Create object of the department class and store the query string inside of it
Department deletedDepartment = (from departmentRecords in db.Departments
where departmentRecords.DepartmentID == DepartmentID
select departmentRecords).FirstOrDefault();
// Remove the selected department from the db
db.Departments.Remove(deletedDepartment);
// Save db changes
db.SaveChanges();
// Refresh gridview
this.GetDepartments();
}
}
/**
* <summary>
* This method gets the department data from the database
* </summary>
* @method GetDepartments
* @return {void}
* */
protected void GetDepartments()
{
// Connect to EF
using (ContosoConnection db = new ContosoConnection())
{
string SortString = Session["SortColumn"].ToString() + " " + Session["SortDirection"].ToString();
// Query the departments table using EF and LINQ
var Departments = (from allDepartments in db.Departments select allDepartments);
// Bind results to gridview
DepartmentsGridView.DataSource = Departments.AsQueryable().OrderBy(SortString).ToList();
DepartmentsGridView.DataBind();
}
}
