How to get data from aws Dynamodb with using partition key only? - amazon-web-services

Question

I am using aws-sdk-go library for DynamoDb connectivity in Golang.
My DynamoDb table have a Partition key DeviceId (String) and a Sort Key Time (Number). How can I write GetItemInput to get all data with a specific DeviceId?
params := &dynamodb.GetItemInput{
Key: map[string]*dynamodb.AttributeValue {
"DeviceId": {
S: aws.String("item_1"),
},
},
ExpressionAttributeNames: map[string]*string{
"DeviceId": "DeviceId",
},
TableName: aws.String("DbName"),
}
list, err := svc.GetItem(params)

Answer 1

You have to use Query or Scan operation, this is a simple example but you can read more on Amazon documentation here
In particular, Query operation
A Query operation finds items in a table or a secondary index using only primary key attribute values
var queryInput = &dynamodb.QueryInput{
TableName: aws.String(dynamoRestDataTableName),
KeyConditions: map[string]*dynamodb.Condition{
"DeviceId": {
ComparisonOperator: aws.String("EQ"),
AttributeValueList: []*dynamodb.AttributeValue{
{
S: aws.String("aDeviceId"),
},
},
},
},
}
var resp, err = dynamoSvc.Query(queryInput)
if err != nil {
return nil, err
}

Answer 2

Query operation can be used in that case
Following is one generic example for the same
compositeKey := entity.GetPrimaryKey(inputVar)
expressionAttributeValues := map[string]*dynamodb.AttributeValue{
":v1": {
S: aws.String(compositeKey.PartitionKey.Data.(string)),
},
}
queryInput := dynamodb.QueryInput{
TableName: &d.TableName,
KeyConditionExpression: aws.String("id = :v1"),
ExpressionAttributeValues: expressionAttributeValues,
}
queryOutput, err := d.DdbSession.Query(&queryInput)
if err != nil {
log.Error("error in fetching records ", err)
return nil, err
}
// unmarshal the query output - items to interface
err = dynamodbattribute.UnmarshalListOfMaps(queryOutput.Items, &yourInterface)

Answer 3

You can use getItem in JavaScript SDK v2 like this
const params = {
TableName: 'tableName',
Key: {
id: { S: id },
},
};
const result = await dynamoDb.getItem(params).promise();
if (result.Item === undefined) {
throw new Error('not found');
}
const item = AWS.DynamoDB.Converter.unmarshall(result.Item)
If JavaScript SDK can do this, I assume golang SDK can also. If not, that means AWS doesn't take all languages equally ?