feat: add get item for Product object

Author: farbodahm

helpers.go

@@ -5,10 +5,10 @@ import (
 	"github.com/farbodahm/dynamodb-optimistic-locking/pkg/tables"
 )
 
-// populateProductsTable populates the products table with sample data.
+// populateProductsTable populates the Product table with sample data.
 func populateProductsTable(dynamo ddb.DynamoDB) error {
 
-	sampleProducts := []tables.Products{
+	sampleProduct := []tables.Product{
 		{Id: "p#0", Name: "Product 0", Quantity: 10, Version: 1},
 		{Id: "p#1", Name: "Product 1", Quantity: 4, Version: 1},
 		{Id: "p#2", Name: "Product 2", Quantity: 2, Version: 1},
@@ -17,11 +17,11 @@ func populateProductsTable(dynamo ddb.DynamoDB) error {
 		{Id: "p#5", Name: "Product 5", Quantity: 0, Version: 1},
 	}
 
-	products := make([]ddb.DynamoDBWritable, len(sampleProducts))
-	for i, product := range sampleProducts {
-		products[i] = product
+	Product := make([]ddb.DynamoDBWritable, len(sampleProduct))
+	for i, product := range sampleProduct {
+		Product[i] = product
 	}
 
-	_, err := dynamo.AddBatch("products", products, 100)
+	_, err := dynamo.AddBatch("products", Product, 100)
 	return err
 }

main.go

@@ -4,6 +4,7 @@ import (
 	"log"
 
 	"github.com/farbodahm/dynamodb-optimistic-locking/pkg/ddb"
+	"github.com/farbodahm/dynamodb-optimistic-locking/pkg/tables"
 	"github.com/spf13/cobra"
 )
 
@@ -32,4 +33,10 @@ func main() {
 			log.Fatalln("Failed to populate products table:", err)
 		}
 	}
+
+	x, err := tables.GetProduct(*dynamo, "p#1")
+	if err != nil {
+		log.Fatalln("Failed to get product:", err)
+	}
+	log.Println(x)
 }

pkg/tables/products.go

@@ -1,12 +1,16 @@
 package tables
 
 import (
+	"log"
+
+	"github.com/aws/aws-sdk-go-v2/feature/dynamodb/attributevalue"
+	"github.com/aws/aws-sdk-go-v2/service/dynamodb/types"
 	"github.com/farbodahm/dynamodb-optimistic-locking/pkg/ddb"
 )
 
 // Products table
-type Products struct {
-	ddb.DynamoDBWritable
+type Product struct {
+	ddb.DynamoDBWritable `dynamodbav:",omitempty"`
 
 	Id       string `dynamodbav:"id"`
 	Name     string `dynamodbav:"name"`
@@ -15,3 +19,31 @@ type Products struct {
 	// Version field is used for implementing Optimistic locking
 	Version int `dynamodbav:"version"`
 }
+
+// GetProduct returns a product with the given id from the products table.
+// If no product with the given id exists, an empty product is returned.
+func GetProduct(d ddb.DynamoDB, id string) (Product, error) {
+	var product Product
+
+	marshaledId, err := attributevalue.Marshal(id)
+
+	if err != nil {
+		log.Printf("WARN: Couldn't marshal product id %v\n", id)
+		return product, err
+	}
+
+	query := map[string]types.AttributeValue{"id": marshaledId}
+	result, err := d.GetItem("products", query)
+
+	if err != nil {
+		log.Printf("WARN: Couldn't get product id %v\n", id)
+		return product, err
+	}
+
+	if err := attributevalue.UnmarshalMap(result, &product); err != nil {
+		log.Printf("WARN: Couldn't unmarshal product id %v\n", id)
+		return product, err
+	}
+
+	return product, nil
+}