/// <summary>
/// Deletes student from database, by their studentID
/// Disconnected Scenario, save trip to DB
/// See Also: https://www.tektutorialshub.com/entity-framework/ef-deleting-records/
/// </summary>
/// <param name="s"></param>
public static void Delete(Student s)
{
using (StudentContext context = new StudentContext()) //using statement vs using directive at the top of the page
{
#if DEBUG
context.Database.Log = Console.WriteLine; // Log query generated to output window
#endif
//context.Students.Add(s); // This looks odd, as we are not trying to reinsert s into the database
context.Students.Attach(s);
context.Entry(s).State = EntityState.Deleted; // removed System.Data.Entity & added using
context.SaveChanges();
}
//// This is what a using statment generates:
//// https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/using-statement
//// manual dispose, the using statement above does this for us
//var context2 = new StudentContext();
//try
//{
// //DB Code goes here
//}
//finally
//{
// context2.Dispose();
//}
}
/// <summary>
/// deletes a student from the database by their studentID
/// </summary>
/// <param name="s"></param>
public static void Delete(Student s)
{
using (var context = new StudentContext())
{
#if DEBUG
//log query generate to output window
context.Database.Log = Console.WriteLine;
#endif
context.Students.Attach(s);
context.Entry(s).State = EntityState.Deleted;
context.SaveChanges();
}
//same as above
/*var context2 = new StudentContext();
* try
* {
* //DB code goes here
* }
* finally
* {
* context2.Dispose();
* }*/
}
/// <summary>
/// if StudentID is 0, will be added
/// else will be updated based on StudentID
/// </summary>
/// <param name="s"></param>
/// <returns></returns>
public static Student AddOrUpdate(Student s)
{
using (var context = new StudentContext())
{
context.Entry(s).State = (s.StudentId == 0) ? EntityState.Added : EntityState.Modified;
context.SaveChanges();
return(s);
}
}
/// <summary>
/// updates all student data except for the primary key
/// </summary>
/// <param name="s"></param>
/// <returns></returns>
public static Student Update(Student s)
{
using (var context = new StudentContext())
{
context.Students.Attach(s);
context.Entry(s).State = EntityState.Modified;
context.SaveChanges();
return(s);
}
}
public static Student Add(Student stu)
{
// Check Panopto video 1/27 to see how to wrap using around this.
StudentContext context = new StudentContext();
context.Students.Add(stu); // Preparing insert query
context.SaveChanges(); // Execute insert query against DB
return(stu); // Return student with StudentId set
}
/// <summary>
/// If StudentId = 0 they will be added
/// else, it will update based upon StudentId
/// </summary>
/// <exception cref="System.Data.Entity.Infrastructure.DbUpdateConcurrencyException"
/// <param name="s"></param>
/// <returns></returns>
public static Student AddOrUpdate(Student s)
{
using (StudentContext context = new StudentContext())
{
//ternary operator, https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/operators/conditional-operator
context.Entry(s).State = (s.StudentId == 0) ? EntityState.Added : EntityState.Modified;
context.SaveChanges();
return(s);
}
}
public static Student Add(Student stu)
{
using (StudentContext context = new StudentContext())
{
//preparing insert query
context.Students.Add(stu);
//execute insert query against DB
context.SaveChanges();
}
//return the student with the studentID set
return(stu);
}
/// <summary>
/// Updates all student data except for PrimaryKey
/// </summary>
/// <param name="s"></param>
/// <returns></returns>
public static Student Update(Student s)
{
using (StudentContext context = new StudentContext()) //using statement vs using directive at the top of the page
{
#if DEBUG
context.Database.Log = Console.WriteLine; // Log query generated to output window
#endif
context.Students.Attach(s);
context.Entry(s).State = EntityState.Modified;
context.SaveChanges();
return(s);
}
}
/// <summary>
/// Updates all student data (except for PK)
/// </summary>
/// <param name="s">The student to be updated</param>
public static Student Update(Student s)
{
using (var context = new StudentContext())
{
#if DEBUG
context.Database.Log = Console.WriteLine;
#endif
context.Students.Attach(s);
context.Entry(s).State = EntityState.Modified;
context.SaveChanges();
return(s);
}
}
public static Student Add(Student stu)
{
using (var context = new StudentContext())
{
#if DEBUG
// Log query generated to output window
context.Database.Log = Console.WriteLine;
#endif
// Generating/preparing insert query
context.Students.Add(stu);
// Executing insert query against DB
context.SaveChanges();
// Return the student with the StudentId set
return(stu);
}
}
