If you're trying to set up a DynamoDB query in Retool and you get the error "One or more parameter values were invalid: Condition parameter type does not match schema type" then is probably because you are using the syntax:
{ ":kind": {"S": "timesheet" } }
in your expression attribute value, it seems underneath that Retool use the "DocumentClient" interface, that will infer the type of the value, so you specify your value like:
{ ":kind": "timesheet" }
After getting that going then I discovered the visual parameter editor did not have a way to specify ScanIndexForward which I needed to to set to false to get the descending order sort I needed by date. There is a workaround for this, but you have to then use the JSON editor (which confusingly is selected by a checkbox that will stay on but then be labelled "Use visual parameter editor"). In my earlier debugging I had recreated my query in the AWS cli, so I was able to sue this with the --debug flag to dig the appropriate JSON out of the log (grep for "Making request for OperationModel" in stderr). I did have to translate back the expression attribute value as above however.
I can't wait for Retool to have an easily accessible local SQL database for simple jobs like what I am working on.
So I can find it later a full query in JSON format might look like:
{
"TableName": "<tablename>",
"IndexName": "<indexname>",
"ScanIndexForward": false,
"KeyConditionExpression": "kind = :kind",
"ExpressionAttributeValues": {
":kind":"timesheet"
}
}