add GetProductsById method and endpoint for retrieving a product by ID

Author: GabrielNat1

cmd/main.go

@@ -32,6 +32,7 @@ func main() {
 
 	server.GET("/products", ProductController.GetProducts)
 	server.POST("/product", ProductController.CreateProduct)
+	server.GET("/product/:productId", ProductController.GetProductsById)
 
 	server.Run(":8000")
 

controller/product_controller.go

@@ -4,6 +4,7 @@ import (
 	"api-go/model"
 	"api-go/usecase"
 	"net/http"
+	"strconv"
 
 	"github.com/gin-gonic/gin"
 )
@@ -45,3 +46,40 @@ func (p *productController) CreateProduct(ctx *gin.Context) {
 
 	ctx.JSON(http.StatusCreated, insertedProduct)
 }
+
+func (p *productController) GetProductsById(ctx *gin.Context) {
+
+	id := ctx.Param("productId")
+	if id == "" {
+		response := model.Reponse{
+			Message: "Product ID cannot be null",
+		}
+		ctx.JSON(http.StatusBadRequest, response)
+		return
+	}
+
+	productId, err := strconv.Atoi(id)
+	if err != nil {
+		response := model.Reponse{
+			Message: "Product Id need to be number",
+		}
+		ctx.JSON(http.StatusBadRequest, response)
+		return
+	}
+
+	product, err := p.productUseCase.GetProductById(productId)
+	if err != nil {
+		ctx.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	if product == nil {
+		response := model.Reponse{
+			Message: "Product not existing in database",
+		}
+		ctx.JSON(http.StatusNotFound, response)
+		return
+	}
+
+	ctx.JSON(http.StatusOK, product)
+}

model/response.go

@@ -0,0 +1,5 @@
+package model
+
+type Reponse struct {
+	Message string
+}

repository/product_repository.go

@@ -66,3 +66,31 @@ func (pr *ProductRepository) CreateProduct(product model.Product) (int, error) {
 	query.Close()
 	return id, nil
 }
+
+func (pr *ProductRepository) GetProductById(id_product int) (*model.Product, error) {
+
+	query, err := pr.connection.Prepare("SELECT * FROM product WHERE od = $1")
+	if err != nil {
+		fmt.Println(err)
+		return nil, err
+	}
+
+	var produto model.Product
+
+	err = query.QueryRow(id_product).Scan(
+		&produto.ID,
+		&produto.Name,
+		&produto.Price,
+	)
+
+	if err != nil {
+		if err == sql.ErrNoRows {
+			return nil, nil
+		}
+
+		return nil, err
+	}
+
+	query.Close()
+	return &produto, nil
+}

usecase/product_usecase.go

@@ -30,3 +30,13 @@ func (pu *ProductUseCase) CreateProduct(product model.Product) (model.Product, e
 
 	return product, nil
 }
+
+func (pu *ProductUseCase) GetProductById(id_product int) (*model.Product, error) {
+
+	product, err := pu.repository.GetProductById(id_product)
+	if err != nil {
+		return nil, err
+	}
+
+	return product, nil
+}