Creating db method to paginate all orders

cmd/api/handlers-api.go

@@ -516,11 +516,35 @@ func (app *application) ResetPassword(w http.ResponseWriter, r *http.Request) {
 }
 
 func (app *application) AllSales(w http.ResponseWriter, r *http.Request) {
-	allSales, err := app.DB.GetAllOrders(false)
+	var payload struct {
+		PageSize    int `json:"page_size"`
+		CurrentPage int `json:"page"`
+	}
+	err := app.readJSON(w, r, &payload)
 	if err != nil {
 		app.badRequest(w, r, err)
 	}
-	app.writeJSON(w, http.StatusOK, allSales)
+
+	allSales, lastPage, totalRecords, err := app.DB.GetAllOrdersPaginated(false, 2, 1)
+	if err != nil {
+		app.badRequest(w, r, err)
+	}
+
+	var resp struct {
+		CurrentPage  int             `json:"current_page"`
+		PageSize     int             `json:"page_size"`
+		LastPage     int             `json:"last_page"`
+		TotalRecords int             `json:"total_records"`
+		Orders       []*models.Order `json:"orders"`
+	}
+
+	resp.CurrentPage = 1
+	resp.PageSize = payload.PageSize
+	resp.LastPage = lastPage
+	resp.TotalRecords = totalRecords
+	resp.Orders = allSales
+
+	app.writeJSON(w, http.StatusOK, resp)
 }
 
 func (app *application) AllSubscriptions(w http.ResponseWriter, r *http.Request) {

internal/models/models.go

@@ -361,6 +361,93 @@ func (m *DBModel) GetAllOrders(isRecurring bool) ([]*Order, error) {
 	return orders, nil
 }
 
+func (m *DBModel) GetAllOrdersPaginated(
+	isRecurring bool,
+	pageSize, page int,
+) ([]*Order, int, int, error) {
+	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
+	defer cancel()
+
+	offset := (page - 1) * pageSize
+
+	orders := []*Order{}
+
+	query := `
+        SELECT
+            o.id, o.widget_id, o.transaction_id, o.customer_id,
+            o.status_id, o.quantity, o.amount, o.created_at, o.updated_at,
+            w.id, w.name, t.id, t.amount, t.currency, t.last_four,
+            t.expiry_month, t.expiry_year, t.payment_intent, t.bank_return_code,
+            c.id, c.first_name, c.last_name, c.email
+        FROM orders o
+            LEFT JOIN widgets w on (o.widget_id = w.id)
+            LEFT JOIN transactions t on (o.transaction_id = t.id)
+            LEFT JOIN customers c on (o.customer_id = c.id)
+        WHERE
+            w.is_recurring = ?
+        ORDER BY
+            o.created_at DESC
+        LIMIT ? OFFSET ?
+    `
+
+	rows, err := m.DB.QueryContext(ctx, query, isRecurring, pageSize, offset)
+	if err != nil {
+		return nil, 0, 0, err
+	}
+	defer rows.Close()
+
+	for rows.Next() {
+		var o Order
+		err = rows.Scan(
+			&o.ID,
+			&o.WidgetID,
+			&o.TransactionID,
+			&o.CustomerID,
+			&o.StatusID,
+			&o.Quantity,
+			&o.Amount,
+			&o.CreatedAt,
+			&o.UpdatedAt,
+			&o.Widget.ID,
+			&o.Widget.Name,
+			&o.Transaction.ID,
+			&o.Transaction.Amount,
+			&o.Transaction.Currency,
+			&o.Transaction.LastFour,
+			&o.Transaction.ExpiryMonth,
+			&o.Transaction.ExpiryYear,
+			&o.Transaction.PaymentIntent,
+			&o.Transaction.BankReturnCode,
+			&o.Customer.ID,
+			&o.Customer.FirstName,
+			&o.Customer.LastName,
+			&o.Customer.Email,
+		)
+		if err != nil {
+			return nil, 0, 0, err
+		}
+		orders = append(orders, &o)
+	}
+
+	query = `
+        SELECT COUNT(o.id)
+        FROM orders o
+        LEFT JOIN widgets w on (o.widget_id = w.id)
+        WHERE w.is_recurring = ?
+    `
+
+	var totalRecords int
+	countRow := m.DB.QueryRowContext(ctx, query, isRecurring)
+	err = countRow.Scan(&totalRecords)
+	if err != nil {
+		return nil, 0, 0, err
+	}
+
+	lastPage := totalRecords / pageSize
+
+	return orders, lastPage, totalRecords, nil
+}
+
 func (m *DBModel) GetOrderByID(ID int) (Order, error) {
 	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
 	defer cancel()