How to save JSON response in dynamodb in GO - json

Question

I want to save a JSON response in aws-dynamodb, I am using aws-dynamodb-sdk. What I'm currently doing is:
func (e *DB) saveToDynamodb(data map[string]interface{}){
params := &dynamodb.PutItemInput{
Item: map[string]*dynamodb.AttributeValue{
"Key": {
M: data,
},
},
TableName: aws.String("Asset_Data"),
}
resp, err := e.dynamodb.PutItem(params)
if err != nil {
fmt.Println(err.Error())
return
}
fmt.Println(resp)
}
But as you can see data is of map[string]interface{} type while the expected type is map[string]*AttributeValue that's why giving compilation error.
Is there any workaround to save a json response?

Answer 1

The best way to put json into DynamoDB is to use the helper functions.
func ExampleMarshal() (map[string]*dynamodb.AttributeValue, error) {
type Record struct {
Bytes []byte
MyField string
Letters []string
Numbers []int
}
r := Record{
Bytes: []byte{48, 49},
MyField: "MyFieldValue",
Letters: []string{"a", "b", "c", "d"},
Numbers: []int{1, 2, 3},
}
av, err := dynamodbattribute.Marshal(r)
return map[string]*dynamodb.AttributeValue{"object":av}, err
}

Answer 2

You should use type assertion in this case.
Give it a try to this:
func (e *DB) saveToDynamodb(data map[string]interface{}){
params := &dynamodb.PutItemInput{
Item: map[string]*dynamodb.AttributeValue{
"Key": {
M: data.(map[string]*dynamodb.AttributeValue), // assert interface to *dynamodb.AttributeValue
},
},
TableName: aws.String("Asset_Data"),
}
resp, err := e.dynamodb.PutItem(params)
if err != nil {
fmt.Println(err.Error())
return
}
fmt.Println(resp)
}

Answer 3

To put JSON in aws-dynamodb we first need to iterate through each attribute of JSON struct and convert it to dynamodb.AttributeValue in the following manner:
func (e *DB) saveToDynamodb(data map[string]interface{}){
var vv=make(map[string]*dynamodb.AttributeValue)
for k,v:=range data{
x:=(v.(string)) //assert string type
xx:=&(x)
vv[k]=&dynamodb.AttributeValue{S: xx,}
}
//s:=data["asset_id"].(string)
params := &dynamodb.PutItemInput{
Item: vv,
TableName: aws.String("Asset_Data"), // Required
}
resp, err := e.dynamodb.PutItem(params)
if err != nil {
// Print the error, cast err to awserr.Error to get the Code and
// Message from an error.
fmt.Println(err.Error())
return
}
// Pretty-print the response data.
fmt.Println(resp)
}