Add NATS integration and order placement refinements

Introduced a new NATS package for message publishing and subscribing. Modified the order placement function to include user ID and ensure cart items are removed post-order placement. Updated dependencies to include NATS-related packages.

cmd/api/main.go

@@ -35,6 +35,9 @@ func main() {
 		log.Fatalf("Error migrating database: %s", err)
 	}
 
+	// Connect NATS
+	//natServer, err := nats.NewNATS()
+
 	s := handler.NewServer(db)
 
 	// Initialize Validator

go.mod

@@ -72,6 +72,9 @@ require (
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
 	github.com/modern-go/reflect2 v1.0.2 // indirect
 	github.com/morikuni/aec v1.0.0 // indirect
+	github.com/nats-io/nats.go v1.37.0 // indirect
+	github.com/nats-io/nkeys v0.4.7 // indirect
+	github.com/nats-io/nuid v1.0.1 // indirect
 	github.com/ncruces/go-strftime v0.1.9 // indirect
 	github.com/opencontainers/go-digest v1.0.0 // indirect
 	github.com/opencontainers/image-spec v1.1.0 // indirect

go.sum

@@ -147,6 +147,12 @@ github.com/modern-go/reflect2 v1.0.2 h1:xBagoLtFs94CBntxluKeaWgTMpvLxC4ur3nMaC9G
 github.com/modern-go/reflect2 v1.0.2/go.mod h1:yWuevngMOJpCy52FWWMvUC8ws7m/LJsjYzDa0/r8luk=
 github.com/morikuni/aec v1.0.0 h1:nP9CBfwrvYnBRgY6qfDQkygYDmYwOilePFkwzv4dU8A=
 github.com/morikuni/aec v1.0.0/go.mod h1:BbKIizmSmc5MMPqRYbxO4ZU0S0+P200+tUnFx7PXmsc=
+github.com/nats-io/nats.go v1.37.0 h1:07rauXbVnnJvv1gfIyghFEo6lUcYRY0WXc3x7x0vUxE=
+github.com/nats-io/nats.go v1.37.0/go.mod h1:Ubdu4Nh9exXdSz0RVWRFBbRfrbSxOYd26oF0wkWclB8=
+github.com/nats-io/nkeys v0.4.7 h1:RwNJbbIdYCoClSDNY7QVKZlyb/wfT6ugvFCiKy6vDvI=
+github.com/nats-io/nkeys v0.4.7/go.mod h1:kqXRgRDPlGy7nGaEDMuYzmiJCIAAWDK0IMBtDmGD0nc=
+github.com/nats-io/nuid v1.0.1 h1:5iA8DT8V7q8WK2EScv2padNa/rTESc1KdnPw4TC2paw=
+github.com/nats-io/nuid v1.0.1/go.mod h1:19wcPz3Ph3q0Jbyiqsd0kePYG7A95tJPxeL+1OSON2c=
 github.com/ncruces/go-strftime v0.1.9 h1:bY0MQC28UADQmHmaF5dgpLmImcShSi2kHU9XLdhx/f4=
 github.com/ncruces/go-strftime v0.1.9/go.mod h1:Fwc5htZGVVkseilnfgOVb9mKy6w1naJmn9CehxcKcls=
 github.com/opencontainers/go-digest v1.0.0 h1:apOUWs51W5PlhuyGyz9FCeeBIOUDA/6nW8Oi/yOhh5U=

pkg/handler/cart/order.go

@@ -2,7 +2,6 @@ package cart
 
 import (
 	"context"
-	"fmt"
 	"github.com/gin-gonic/gin"
 	"net/http"
 	"strconv"
@@ -19,13 +18,19 @@ func (s *CartHandler) PlaceNewOrder(c *gin.Context) {
 		c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
 		return
 	}
-
-	order, err := s.service.PlaceOrder(ctx, cartInfo.CartID)
+	// Place a new order.
+	_, err = s.service.PlaceOrder(ctx, cartInfo.CartID, userID)
+	if err != nil {
+		c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+	// Remove all items from the cart after placing order.
+	err = s.service.RemoveItemsFromCart(ctx, cartInfo.CartID)
 	if err != nil {
 		c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
 		return
 	}
-	fmt.Println(order)
+
 	c.JSON(http.StatusCreated, gin.H{"message": "Order placed!"})
 
 }

pkg/nats/nats_server.go

@@ -0,0 +1,36 @@
+package nats
+
+import (
+	"github.com/nats-io/nats.go"
+	"log"
+)
+
+type NATS struct {
+	conn *nats.Conn
+}
+
+func NewNATS() (*NATS, error) {
+	nc, err := nats.Connect(nats.DefaultURL, nats.Name("food-delivery-nats"))
+	if err != nil {
+		log.Fatalf("Error: %s", err)
+	}
+	return &NATS{conn: nc}, err
+}
+
+func (n *NATS) Publish(channel string, message []byte) error {
+	err := n.conn.Publish(channel, message)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func (n *NATS) Subscribe(channel string) error {
+	_, err := n.conn.Subscribe(channel, func(msg *nats.Msg) {
+		log.Printf("Received a message: %s", string(msg.Data))
+	})
+	if err != nil {
+		return err
+	}
+	return nil
+}

pkg/service/cart_order/place_order.go

@@ -8,7 +8,7 @@ import (
 	"errors"
 )
 
-func (cartSrv *CartService) PlaceOrder(ctx context.Context, cartId int64) (*order.Order, error) {
+func (cartSrv *CartService) PlaceOrder(ctx context.Context, cartId int64, userId int64) (*order.Order, error) {
 	var cartItems []cart.CartItems
 	var newOrder order.Order
 	var newOrderItems []order.OrderItems
@@ -26,7 +26,7 @@ func (cartSrv *CartService) PlaceOrder(ctx context.Context, cartId int64) (*orde
 	}
 
 	// Creating a new order.
-	newOrder.UserID = 1
+	newOrder.UserID = userId
 	newOrder.OrderStatus = "pending"
 	newOrder.TotalAmount = orderTotal
 	newOrder.DeliveryAddress = "New Delhi"
@@ -56,12 +56,16 @@ func (cartSrv *CartService) PlaceOrder(ctx context.Context, cartId int64) (*orde
 		return nil, err
 	}
 
+	return &newOrder, nil
+
+}
+
+func (cartSrv *CartService) RemoveItemsFromCart(ctx context.Context, cartId int64) error {
 	//remove all items from the cart.
 	filter := database.Filter{"cart_id": cartId}
-
-	_, err = cartSrv.db.Delete(ctx, "cart_items", filter)
+	_, err := cartSrv.db.Delete(ctx, "cart_items", filter)
 	if err != nil {
-		return nil, errors.New("failed to delete cart items")
+		return errors.New("failed to delete cart items")
 	}
-	return nil, err
+	return nil
 }