dynamodb_get_item.go

package main

import (
	"fmt"

	"github.com/aws/aws-sdk-go/aws"
	"github.com/aws/aws-sdk-go/aws/session"
	"github.com/aws/aws-sdk-go/service/dynamodb"
	"github.com/aws/aws-sdk-go/service/dynamodb/dynamodbattribute"
	"github.com/aws/aws-sdk-go/service/dynamodb/dynamodbiface"
)

var (
	conf *Config
	err  error
)

type Config struct {
	DynamoDB dynamodbiface.DynamoDBAPI
}

type Item struct {
	PlayerName struct {
		Value string
	}
	JerseyNumber struct {
		Value string
	}
}

func InitializeConfig() (*Config, error) {
	sess, err := session.NewSession(&aws.Config{
		Region: aws.String("us-east-1")},
	)
	if err != nil {
		return &Config{}, fmt.Errorf("unable to create a session to aws with error: %v", err)
	}

	return &Config{
		DynamoDB: dynamodb.New(sess),
	}, nil
}

func getItem(conf *Config, table string, item *Item) (map[string]string, error) {
	var m map[string]string
	result, err := conf.DynamoDB.GetItem(&dynamodb.GetItemInput{
		TableName: aws.String(table),
		Key: map[string]*dynamodb.AttributeValue{
			"PlayerName": {
				S: aws.String(item.PlayerName.Value),
			},
			"JerseyNumber": {
				N: aws.String(item.JerseyNumber.Value),
			},
		},
	})
	if err != nil {
		return m, fmt.Errorf("failed to get item from dynamodb: %s", err)
	}

	err = dynamodbattribute.UnmarshalMap(result.Item, &m)
	if err != nil {
		return m, fmt.Errorf("failed to marshal map of the item in table struct, error: %s", err)
	}

	return m, nil
}

func init() {
	conf, err = InitializeConfig()
	if err != nil {
		panic(fmt.Sprintf("unable to initalize the configuration"))
	}
}

func main() {
	i := &Item{}
	i.PlayerName.Value = "Manu Ginobili"
	i.JerseyNumber.Value = "20"

	item, err := getItem(conf, "SanAntonioSpurs", i)
	if err != nil {
		fmt.Printf("error while trying to retrieve item from dynamodb: %v", err)
	}
	fmt.Println(item)
}