AWS Step Function get all Range keys with a single primary key in DynamoDB - amazon-web-services

Question

I'm building AWS Step Function state machines. My goal is to read all Items from a DynamoDB table with a specific value for the Hash key (username) and any (wildcard) Sort keys (order_id).
Basically something that would be done from SQL with:
SELECT username,order_id FROM UserOrdersTable
WHERE username = 'daffyduck'
I'm using Step Functions to get configurations for AWS Glue jobs from a DynamoDB table and then spawn a Glue job via step function's Map for each dynamodb item (with parameters read from the database).
"Read Items from DynamoDB": {
"Type": "Task",
"Resource": "arn:aws:states:::dynamodb:getItem",
"Parameters": {
"TableName": "UserOrdersTable",
"Key": {
"username": {
"S": "daffyduck"
},
"order_id": {
"S": "*"
}
}
},
"ResultPath": "$",
"Next": "Invoke Glue jobs"
}
But I can't bring the state machine to read all order_id's for the user daffyduck in the step function task above. No output is displayed using the code above, apart from http stats.
Is there a wildcard for order_id ? Is there another way of getting all order_ids? The query customization seems to be rather limited inside step functions:
https://docs.amazonaws.cn/amazondynamodb/latest/APIReference/API_GetItem.html#API_GetItem_RequestSyntax
Basically I'm trying to accomplish what can be done from the command line like so:
$ aws dynamodb query \
--table-name UserOrdersTable \
--key-condition-expression "Username = :username" \
--expression-attribute-values '{
":username": { "S": "daffyduck" }
}'
Any ideas? Thanks

Answer 1

I don't think that is possible with Step functions Dynamodb Service yet.
currently supports get, put, delete & update Item, not query or scan.
For GetItem we need to pass entire KEY (Partition + Range Key)
For the primary key, you must provide all of the attributes. For
example, with a simple primary key, you only need to provide a value
for the partition key. For a composite primary key, you must provide
values for both the partition key and the sort key.
We need to write a Lambda function to query Dynamo and return a map and invoke the lambda function from step.