public void Update(BOOK bookObj)
{
using (var db = new LibDb())
{
var b = db.BOOKs.Include(x => x.AUTHORs).ToList().Find(d => d.ISBN ==
bookObj.ISBN);
b.AUTHORs.Clear();
db.SaveChanges();
}
var newAuthors = bookObj.AUTHORs;
bookObj.AUTHORs = new List <AUTHOR>();
using (var db = new LibDb())
{
db.BOOKs.Attach(bookObj);
db.Entry(bookObj).State = EntityState.Modified;
foreach (var author in newAuthors)
{
db.AUTHORs.Attach(author);
bookObj.AUTHORs.Add(author);
}
db.SaveChanges();
}
}
public void Delete(BOOK bookObj)
{
using (var db = new LibDb())
{
using (DbContextTransaction transaction = db.Database.BeginTransaction())
{
db.BOOKs.Attach(bookObj);
foreach (var au in bookObj.AUTHORs)
{
db.AUTHORs.Attach(au);
}
try
{
bookObj.AUTHORs.Clear();
db.BOOKs.Remove(bookObj);
db.SaveChanges();
transaction.Commit();
}
catch (Exception ex)
{
transaction.Rollback();
}
}
}
}
public void Delete(AUTHOR author)
{
using (var db = new LibDb())
{
using (DbContextTransaction transaction = db.Database.BeginTransaction())
{
db.AUTHORs.Attach(author);
foreach (var bo in author.BOOKs)
{
db.BOOKs.Attach(bo);
}
try
{
author.BOOKs.Clear();
db.AUTHORs.Remove(author);
db.SaveChanges();
transaction.Commit();
}
catch (Exception ex)
{
transaction.Rollback();
}
}
}
}
public void Update(AUTHOR authorObj)
{
using (var db = new LibDb())
{
var b = db.AUTHORs.Include(x => x.BOOKs).ToList().Find(d => d.Aid ==
authorObj.Aid);
b.BOOKs.Clear();
db.SaveChanges();
}
var newBooks = authorObj.BOOKs;
authorObj.BOOKs = new List <BOOK>();
using (var db = new LibDb())
{
db.AUTHORs.Attach(authorObj);
db.Entry(authorObj).State = EntityState.Modified;
foreach (var book in newBooks)
{
db.BOOKs.Attach(book);
authorObj.BOOKs.Add(book);
}
db.SaveChanges();
}
}
public void Update(USER user)
{
using (var db = new LibDb())
{
db.USERs.Attach(user);
db.Entry(user).State = EntityState.Modified;
db.SaveChanges();
}
}
public void Delete(USER user)
{
using (var db = new LibDb())
{
using (DbContextTransaction transaction = db.Database.BeginTransaction())
{
db.USERs.Attach(user);
try
{
db.USERs.Remove(user);
db.SaveChanges();
transaction.Commit();
}
catch (Exception ex)
{
transaction.Rollback();
}
}
}
}
public void Add(BOOK bookObj)
{
using (var db = new LibDb())
{
using (DbContextTransaction transaction = db.Database.BeginTransaction())
{
try
{
foreach (var au in bookObj.AUTHORs)
{
db.AUTHORs.Attach(au);
}
db.BOOKs.Add(bookObj); // Prepare query
db.SaveChanges(); // Run the query
transaction.Commit(); // Permanent the result, writing to disc and closing transaction
}
catch (Exception ex)
{
transaction.Rollback(); //Undo all changes if exception is thrown
}
}
}
}
