private void transactionTypeChanged(object sender, EventArgs e)
        {
            var selection = transactionTypeComboBox.SelectedItem;

            if (selection.ToString() == "Expense")
            {
                selectedTransactionType = Models.TransactionType.Expense;
                LoadCategories();
            }
            else
            {
                selectedTransactionType = Models.TransactionType.Income;
                LoadCategories();
            }
        }
        private void AddNewTransactionView_Load(object sender, EventArgs e)
        {
            LoadTransactionTypes();
            LoadContacts();
            LoadCategories();

            if (isUpdating)
            {
                var categeoryId = updatingTransaction.Category.Id;
                var contactId   = updatingTransaction.Contact.Id;

                amountNumericUpDown.Value      = (decimal)updatingTransaction.Amount;
                contactsComboBox.SelectedValue = contactId;
                datePicker.Value = updatingTransaction.DateTime;

                if (updatingTransaction.TransactionType == Models.TransactionType.Expense)
                {
                    selectedTransactionType = Models.TransactionType.Expense;
                    LoadCategories();
                    transactionTypeComboBox.SelectedItem = transactionTypeComboBox.Items[0];
                }
                else
                {
                    selectedTransactionType = Models.TransactionType.Income;
                    LoadCategories();
                    transactionTypeComboBox.SelectedItem = transactionTypeComboBox.Items[1];
                }

                categoriesComboBox.SelectedValue = categeoryId;

                // save button
                saveButton.Location = new Point(
                    contactsComboBox.Location.X - 130,
                    contactsComboBox.Location.Y + 60);
                // delete button
                Button deleteButton = new Button();
                deleteButton.Size     = saveButton.Size;
                deleteButton.Font     = saveButton.Font;
                deleteButton.Text     = "Delete";
                deleteButton.Location = new Point(
                    contactsComboBox.Location.X + 10,
                    contactsComboBox.Location.Y + 60);
                this.Controls.Add(deleteButton);

                deleteButton.Click += DeleteButton_Click;
            }
        }