private void btnAdd_Click(object sender, EventArgs e) { string bookName = txtBookName.Text; string bookGenre = txtBookGenre.Text; string bookPrice = txtPrice.Text; //string bookAuthor = txtAuthorName.Text; string bookDescript = txtBookDascript.Text; // secilmish qrupun ID nomresinin groupID-ye verilmesi string authorId = ((BookComboBox)cmbAuthor.SelectedItem).Value; // Author tipinden deyishen yaradiriq // ve author siyahisinin ID-lerinden secilmishini deyishene veririk Author selectedAuthor = AuthorList.GetAuthorByID(authorId); if (selectedAuthor == null) // eger secilmish author yoxdursa { MessageBox.Show("Author doesn't exist"); return; } if (string.IsNullOrEmpty(bookName)) { // ERROR mesajinin verilmersi MessageBox.Show("Book name is not valid", "Failed!", MessageBoxButtons.OK, MessageBoxIcon.Error); return; } if (string.IsNullOrEmpty(bookGenre)) { // ERROR mesajinin verilmersi MessageBox.Show("Book genre is not valid", "Failed!", MessageBoxButtons.OK, MessageBoxIcon.Error); return; } if (string.IsNullOrEmpty(bookDescript)) { // ERROR mesajinin verilmersi MessageBox.Show("Book description is not valid", "Failed!", MessageBoxButtons.OK, MessageBoxIcon.Error); return; } if (string.IsNullOrEmpty(bookPrice)) { // ERROR mesajinin verilmersi MessageBox.Show("Book price is not valid", "Failed!", MessageBoxButtons.OK, MessageBoxIcon.Error); return; } // eger AuthorListde bu ad varsa if (BookList.ContainsBookName(bookName)) { // ERROR mesaji verilir MessageBox.Show("Book name is duplicate", "Failed!", MessageBoxButtons.OK, MessageBoxIcon.Error); return; } BookList.AddBook(new Book { BookName = bookName, BookJenre = bookGenre, Price = bookPrice, Description = bookDescript, Authors = selectedAuthor, }); txtBookName.Text = ""; txtBookGenre.Text = ""; txtBookDascript.Text = ""; txtPrice.Text = ""; }